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Blog - MegiQ - RF Development tools - MegiQ - RF Development tools https://www.megiq.com Wed, 19 Feb 2020 23:34:20 +0000 en-gb MegiQ moves to a new office https://www.megiq.com/blog/item/63-megiq-moves-to-a-new-office https://www.megiq.com/blog/item/63-megiq-moves-to-a-new-office MegiQ RF and IOT Development tools
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roger.denker@megiq.com (Super User) Application Notes Fri, 28 Jun 2019 10:22:38 +0000
Perform Cost-Effective Antenna Radiation Measurements https://www.megiq.com/blog/item/62-perform-cost-effective-antenna-radiation-measurements https://www.megiq.com/blog/item/62-perform-cost-effective-antenna-radiation-measurements MWRF Magazine tests MegiQ RMS-0660

The university of Rijeka, Croatia, has recently purchased a MegiQ RMS-0640 antenna measurement system and professor Joler has put the system through its paces and shared his experience in this article.

"This capability to measure simultaneous H and V radiation field components can greatly speed the measurement process"

"The PC software is extremely user-friendly and enables AUT measurements even without an anechoic chamber. The system is well thought out, even to the intelligent rotation of the turntable, which prevents overstretching of the interconnecting cables. All assembly instructions lead to the construction of an automated system fully capable of producing genuine antenna 3D radiation patterns."

Read the full article in MWRF magazine: https://www.mwrf.com/test-measurement/perform-cost-effective-antenna-radiation-measurements

 

 

 

 

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info@megiq.com (MegiQ) Application Notes Tue, 04 Sep 2018 11:48:26 +0000
New videos: VNA Tutorial in 3 parts https://www.megiq.com/blog/item/61-new-videos-vna-tutorial-in-3-parts https://www.megiq.com/blog/item/61-new-videos-vna-tutorial-in-3-parts MegiQ VNA tutorial videos

 

MegiQ has released a video introduction about VNA measurements. It gives an overview of basic VNA concepts, Calibration and actual measurements. The introduction is intended for those that want to get familiar with VNA measurements and their purpose.

The series is divided in three parts:

  1. Basic VNA concept and operation
  2. Calibration
  3. Measurement of 1-port and 2-port circuits, antenna matching, active circuits and parametric sweeps

Watch the VNA tutorial

MegiQ VNAs are the most compact, affordable pro-grade VNA in the market and are popular for wireless product development, component verification and production testing.

Visit the VNA-0460 Product Page or view the VNA Product Sheet

 

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info@megiq.com (MegiQ) Application Notes Thu, 12 Jul 2018 11:17:01 +0000
New VNA Software and Firmware releases 1.9.001 https://www.megiq.com/blog/item/60-new-vna-software-and-firmware-releases-1-9-001 https://www.megiq.com/blog/item/60-new-vna-software-and-firmware-releases-1-9-001 New VNA Software and Firmware releases 1.9.001

 

What’s new in VNA version 1.9.001 and Firmware version 1.9.001

 

New features

  • The measuring speed is improved by a factor 4
  • Enhanced graphs with selectable line width, marker font size and marker transparency
  • Robust software operation during sweeping
  • Robust USB connect and disconnect handling
  • Several small improvements and corrections

Measuring speed

The measuring speed has been improved by a new sampling scheme. At the highest speed the measuring times are:

 

Points     Freq Range            1-port     2-port

4000        400 – 6000 MHz     1000 ms  2000 ms

25            400 – 6000 MHz     21 ms      41 ms

25            400 – 500 MHz       17 ms      33 ms

 

The improved speed gives the VNA a real-time look and feel up to several hundred points sweep size. In addition this makes our VNAs attractive for high speed production testing.

Enhanced graphs

VNA Graph Parametric

 

The software now used GDI+ for enhanced features as anti-aliasing, line width, transparency and smoothing.

We added settings for line width, marker size and marker transparency for each screen representation and report output.

Robust software operation during sweeping

Some users were experiencing problems when changing sweep settings during sweep mode. This has been addressed and is correctly handled now.

Application software installation

Download SetupMiQVNA-1.9.001.exe from the MegiQ site.

Run SetupMiQVNA-1.9.001.exe.

It is not necessary to uninstall older versions.

Firmware update

Download the firmware file VNA-VF201-1.9.001.vfw from the MegiQ site.

Press the Options button and go to the VNA tab.

Press the Firmware button

Browse for the firmware file and press Send Firmware. The VNA will reboot after the upload is complete.

 

 

 

Download the latest software and firmware from our Download area.

 

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info@megiq.com (MegiQ) Application Notes Fri, 20 Apr 2018 12:56:52 +0000
Get Your Hands Dirty with These VNA Tools https://www.megiq.com/blog/item/58-mwrf-magazine-tests-the-vna0460e https://www.megiq.com/blog/item/58-mwrf-magazine-tests-the-vna0460e MWRF Magazine tests MegiQ VNA0460e

...These results demonstrate that MegiQ’s VNAs can deliver performance that is comparable to other VNAs on the market today.

... In summary, MegiQ has proven that it offers quality VNA solutions at an affordable price. The company’s VNAs include some features—most notably the built-in bias generator—that are typically only found in more expensive high-end VNAs.

... If you’re in the market for a VNA, don’t overlook MegiQ.

 

Read the complete article here: http://www.mwrf.com/test-measurement/get-your-hands-dirty-these-vna-tools

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info@megiq.com (MegiQ) Application Notes Thu, 01 Feb 2018 15:16:02 +0000
MegiQ seminar at RF Technology Days 2018 https://www.megiq.com/blog/item/59-megiq-seminar-at-rf-technology-days-2018 https://www.megiq.com/blog/item/59-megiq-seminar-at-rf-technology-days-2018 RF Technology days 2018

The workshop will be held on April 18, in Veenendaal, the Netherlands.

More information about the RF Technology Days

Register here

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info@megiq.com (MegiQ) Application Notes Fri, 06 Apr 2018 14:12:26 +0000
MegiQ seminar on Antenna Development at Wireless Congress 2017 in Munich https://www.megiq.com/blog/item/57-megiq-seminar-on-antenna-development-at-wireless-congress-2017-in-munich https://www.megiq.com/blog/item/57-megiq-seminar-on-antenna-development-at-wireless-congress-2017-in-munich Wireless Congress Munchen

As part of the Antenna Workshop, MegiQ holds a seminar for the second time on antenna development for ISM frequencies and the antenna characteristics that are important. The focus will be on early prototype development and how to monitor the RF characteristics during the development cycle. Live measurements demonstrate how to efficiently measure antenna impedance and radiation characteristics.

The workshop will be held on November 15, 2017, starting at 16:00 at the Wireless Congress and Productronica fair in Munich.

More information about the Wireless Conference at www.wireless-congress.com.

Get the program overview: Program Wireless Congress 2017

MegiQ seminar on Antenna Development at Wireless Congress in Munich

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info@megiq.com (MegiQ) Application Notes Thu, 09 Nov 2017 14:08:49 +0000
MegiQ VNAs get a new cabinet https://www.megiq.com/blog/item/56-megiq-vnas-in-new-cabinet https://www.megiq.com/blog/item/56-megiq-vnas-in-new-cabinet MegiQ VNA0460 and VNA0460e in new cabinet

MegiQ VNA0440 New Cabinet

The new all aluminum cabinets provide better shielding and isolation, improved thermal management and a more solid look and feel.

All MegiQ VNAs are now shipped with the new cabinet.

 

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info@megiq.com (MegiQ) Application Notes Sat, 16 Sep 2017 12:25:00 +0000
MegiQ VNAs at Complutense University in Madrid https://www.megiq.com/blog/item/55-megiq-vnas-at-complutense-university-in-madrid https://www.megiq.com/blog/item/55-megiq-vnas-at-complutense-university-in-madrid MegiQ VNAs at Complutense University in Madrid

 

"I discovered MegiQ VNAs and it was exactly what we needed."

 

Read the full article in Electronic Design.

Electronic Design

 

 

Luis Angel Tejedor
Luis Ángel Tejedor has served as an Associate Professor at Complutense University of Madrid since 2016, teaching high-frequency electronics for the degree of Communications Electronics Engineering. He received a master degree in Telecommunication Engineering in 2006 and a Ph. D. in Telecommunications Engineering in 2014, both from the Polytechnic University of Madrid.
Between 2007 and 2009, he worked as RF engineer in the Eurofighter program at Indra Sistemas S.A. Since 2009, he has worked at the Physics Faculty of the Complutense University of Madrid, designing electronic systems for gamma-ray Cherenkov telescopes, in the MAGIC and CTA projects. He has over 10 years of experience designing low-frequency, high-frequency and digital circuits.
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info@megiq.com (MegiQ) Application Notes Thu, 20 Jul 2017 19:05:00 +0000
New VNA Software and Firmware releases 1.7.1 https://www.megiq.com/blog/item/54-new-vna-software-and-firmware-releases-1-7-1 https://www.megiq.com/blog/item/54-new-vna-software-and-firmware-releases-1-7-1 New VNA Software and Firmware releases 1.7.1

 

What’s new in VNA version 1.7.01 and Firmware version 1.7.01

New features

  • The measuring speed is improved by a factor 3
  • Measuring speed is now selectable as Fast / Medium / Slow
  • Support for Calibration Kit coefficients and S-parameter correction
  • Command line option to reset user configuration
  • More extensive Touchstone import and export support, also CSV format
  • Linear Gain graph
  • Deembedding of Through path
  • Return Loss graph can also show Phase / Group delay
  • Improved graphic representation of Match Circuit
  • Several small improvements and corrections, improved error handling

Match circuit representation

Some users were confused about the drawing of the calculated match circuits.

 MatchCircuit

We have changed the representation slightly for clarity.

Port setup and Calibration kits

The VNA software now supports calibration kits and Port Connector types.

CalKitManager

Session Data

The session and configuration data format has been upgraded to be more robust.

The latest version can read data from versions before 1.7.0, but it stores the data in a new format that can not be read with older versions. The software will warn the user if a older data is saved in the new format.

The old VNA software version can not read the new format. This software will give the error “Type Mismatch” when trying to read a new file. This error is invoked on purpose.

VNA Sandbox

For the VNA Sandbox, select ‘UFL-VSB’ connector and ‘Neutral’ gender. Since we are calibrating on the PCB and not on the connectors, do not select ‘UFL connectors’.

Download

Download the latest software and firmware from our Download area.

 

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info@megiq.com (MegiQ) Application Notes Sun, 11 Jun 2017 12:51:00 +0000
MegiQ RMS in Microwaves and RF https://www.megiq.com/blog/item/52-megiq-rms-in-microwaves-and-rf https://www.megiq.com/blog/item/52-megiq-rms-in-microwaves-and-rf MegiQ RMS in Microwaves and RF
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roger.denker@megiq.com (Super User) Application Notes Thu, 01 Dec 2016 14:13:00 +0000
MegiQ seminar on Antenna Development at Wireless Congress in Munich https://www.megiq.com/blog/item/51-megiq-seminar-on-antenna-development-at-wireless-congress-in-munich https://www.megiq.com/blog/item/51-megiq-seminar-on-antenna-development-at-wireless-congress-in-munich Wireless Congress Munchen

As part of the Antenna Workshop, MegiQ holds a seminar on antenna development for ISM frequencies and the antenna characteristics that are important. The focus will be on early prototype development and how to monitor the RF characteristics during the development cycle. Live measurements demonstrate how to efficiently measure antenna impedance and radiation characteristics.

The workshop will be held on November 10, 2016, starting at 14:30 at the Wireless Congress and Electronica fair in Munich.

More information about the Wireless Conference at www.wireless-congress.com.

Get the program overview: Program Wireless Congress 2016

MegiQ seminar on Antenna Development at Wireless Congress in Munich

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info@megiq.com (MegiQ) Application Notes Tue, 01 Nov 2016 22:05:11 +0000
New videos: RMS-0740 measures antenna patterns https://www.megiq.com/blog/item/50-new-videos-rms-0740-measures-antenna-patterns https://www.megiq.com/blog/item/50-new-videos-rms-0740-measures-antenna-patterns MegiQ RMS-0740 measures antenna patterns

MegiQ has released three videos that show the operation of the RMS-0740 during antenna measurements. They give an overview of the RMS-0740 test system, the software operation and the setup of the different measurements. They also show some of the display options for different result formats.

The videos show the measurement of:

  1. Basic antenna pattern measurement
  2. Radiated harmonics level
  3. Wideband antenna frequency response and wideband radiation patterns

Watch the RMS-0740 videos on Youtube

The Radiation Measurement System (RMS-0740) is a unique turnkey system that will measure Radiation Patterns and Total Radiated Power (TRP) from 700MHz to 4GHz from a 3-axis rotation. While this is usually measured in an anechoic chamber to avoid reflections to affect the measurement, the RMS has a smart antenna design to reduce the sensitivity for reflections. This allows radiation measurements to be made in relatively small lab or office spaces.

Visit the RMS-0740 Product Page or view the RMS-0740 Product Sheet

 

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info@megiq.com (MegiQ) Application Notes Wed, 14 Sep 2016 12:15:15 +0000
5 ways to measure Antenna Radiation https://www.megiq.com/blog/item/49-5-ways-to-measure-antenna-radiation https://www.megiq.com/blog/item/49-5-ways-to-measure-antenna-radiation

1. We followed the datasheets so what can go wrong?

  • Every antenna needs a ground plane. Most datasheets are based on a large PCB with ample ground area. If the product is smaller than the reference board the performance deteriorates dramatically.
  • Some antennas are narrowband, they have a critical tuning and production variations.
  • Where is the battery located? Display in front of the antenna? Potting? Hand-effects? Cables? Who decided on an all metal cabinet?

2. It works pretty good so it must be OK!

  • This is the main danger in designing cellular applications. The cellular network is quite forgiving in urban areas. Even poor designs work pretty well in the lab.
  • However, when the going gets tough in rural areas or basements, poor designs will fail due to lack of RF performance.
  • When operating near a base station the transmit power is low and the device may work well.
  • When operating far from a base station the transmit power is at its maximum and may cause all kinds of internal failure in power supply, microprocessor or peripherals, especially with a bad antenna implementation.

3. Let’s see how far it goes

  • Walk around in the building to see how far it goes: Is this the same building as that of the end user? Do they have the same furniture? Are we walking away or towards the source?
  • Walk around in the field to see how far it goes: Find a large enough field. Make a portable installation. Make a fixture to not disturb the radiation. Walk large distances.
  • Oh yeah, what about polarization, or top-bottom radiation?

4. Why don’t we screw an antenna on the spectrum analyzer and measure the received power . (build a Bob detector)

  • Take an antenna and screw it on the spectrum analyzer. Take the EUT and put it at a distance. Turn the EUT around and look at the power readings.
  • Uhm, the power varies by 10dB when the EUT moves just a little.
  • Uhm, the power drops 7dB when Bob is not at his workplace. Bob’s leave must be cancelled!
  • Oh yeah, what about polarization?

5. Let’s wait for the certification measurements at the test-lab.

  • During the certification measurements we get official figures from the test lab. Then we’ll know exactly the performance!
  • Not all certification protocols yield useful radiation numbers. They are not measured for performance but for interference.
  • What if the performance is not good enough? Can we solve it with components? Do we need a redesign? Is the whole concept bad? Do we need to redo the certification? How much is this going to cost? What about the planned production? How do we break it to the management? What do we tell the customers?
  • This is like renting a multimeter at the end of the project.

 

There is an affordable way to optimize your product and verify its wireless performance:

RMS-0740 Product page

 

We followed the datasheets so what can go wrong?
It works pretty good, so it must be OK!
Let’s see how far it goes
Why don’t we screw an antenna on the spectrum analyzer and measure the received power
Let’s wait for the certification measurements at the test-lab
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info@megiq.com (MegiQ) Application Notes Thu, 11 Aug 2016 22:43:46 +0000
New 6GHz Vector Network Analyzer from MegiQ https://www.megiq.com/blog/item/48-new-6ghz-vna-from-megiq https://www.megiq.com/blog/item/48-new-6ghz-vna-from-megiq MegiQ VNA-0460e 6 GHz Vector Network Analyzer

 

The VNA-0460 is a full two-port VNA that is controlled through a USB connection by a PC. It’s compact size makes it suitable for busy workbenches and allows for short connections to the device under development.

This VNA is ideal for measuring all kinds of micro-circuits like antennas, attenuators, amplifiers etc. Its frequency range covers all popular telecom bands like GSM-GPRS-LTE, Wifi, DECT, GPS, ISM, Zigbee, Bluetooth etc.

The VNA-0460e is an enhanced version with an extra generator port for 3-port measurements and a built-in Bias Voltage/Current generator for active circuits. Since the bias settings can be included in a parametric sweep this VNA can characterise active circuit with varying bias voltages and currents.

The software has an easy and straightforward user interface while at the same time allowing enhanced measurements such as parametric sweeps and flexible port setup. A powerful feature is the built-in Match Circuit calculator that calculates and simulates a (antenna) matching network in real-time.

A session manager organizes the measurements including all calibration data and a report generator supports professional development and documentation of the measurements.

The MegiQ UFL and Balanced calibration kit make it possible to measure the ever smaller RF devices and keep up with IOT developments. The MegiQ VNA-Sandbox offers a quick learning platform for VNA measurements.

VNA-0460 Product page

VNA-0460e Product page

 

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info@megiq.com (MegiQ) Application Notes Wed, 13 Jul 2016 23:10:22 +0000
Calculating TIS from TRP https://www.megiq.com/blog/item/46-calculating-tis-from-trp https://www.megiq.com/blog/item/46-calculating-tis-from-trp Radiation pattern yields TRP

 

TRP and TIS measurement

Many modern wireless specifications require the Total Radiated Power (TRP) and Total Isotropic Sensitivity (TIS) of a wireless device to comply to a certain class of devices.

The TRP is measured by measuring the radiated power at many points around the device and sum the values to the total power radiated.

The TIS measurement is similar but a lot more involved because the sensitivity must be measured at many points. Not only does the measurement need to ‘speak’ the protocol but the determination of sensitivity for each measurement point takes a lot more time.

TRP and TIS measurement

Radiation patterns are integrated for TRP and TIS

Many developers turn to test laboratories for these measurements but there are alternatives. With a substantial budget there are different kinds of test chambers (BlueLab, Satimo) available that can perform the TRP and, with optional components, also TIS measurements.

The MegiQ Radiation Measurement System (RMS) is capable of performing TRP measurements at a fraction of the cost but with similar accuracy. When the properties of the RF transceiver (chip) are known or measured, the TIS can be derived from the TRP results with only one additional, non-critical, sensitivity measurement.

Receiver interference

Wireless devices are usually part of a larger system that involves fast microprocessors, displays and switched power supplies. When the antenna is integrated in the device the other components can create significant amounts of in-band interfering noise that is picked up by the antenna. This raises the effective noise floor and impedes the receiver sensitivity. This is often a significant problem for devices that operate below 1.5GHz but the problem can also occur in the Wifi band.

The internal noise causes a degradation of the sensitivity and this is the main reason why the TIS is such an important number. It expresses the actual sensitivity under the working conditions of the device.

This implies a radiated sensitivity measurement and seemingly points us back to the test lab with calibrated and anechoic test setups. There is however a method that uses the receiver RSSI and does not require a calibrated radiated signal path for the sensitivity measurements.

MegiQ RMS Collage

The MegiQ RMS-0740 measures TRP

Relationship between TRP and TIS

Most wireless devices use the same antenna for both transmitting and receiving. Since the received signal goes through the same antenna as the transmitted signal, they both get the same antenna gain in their path.

The signal in a certain direction is amplified by the gain of the antenna in that direction. If the gain is greater than 0dB the signals gets amplified, otherwise it is attenuated by the antenna. Both TRP and TIS depend on the same antenna gain.

Isotropic radiation

‘Isotropic’ means that the device is compared to a theoretical Isotropic radiator, an antenna that radiates the same power in all directions. Its radiation power is a perfect sphere. This is a standard antenna and has a gain (in all directions) of 0dBi. The ‘i’ indicates that the number compares to the Isotropic radiator, but it is often left out.

A real world antenna will always have a directional character and the gain in some directions is greater than in other directions. The TRP (it is also called Total Isotropic Power, TIP) is calculated by integrating the radiated power over a sphere around the antenna and this yields a power value that can be compared to that of the same transmitter connected to an Isotropic radiator.

Likewise, the TIS is calculated by integrating the sensitivity over the sphere and this yields a sensitivity value that can be compared with the same receiver connected to an Isotropic radiator.

Deriving TIS from TRP

When the TRP is known (measured) and the conducted power of the transmitter is known (measured) the gain of the antenna can be calculated by dividing TRP by the transmit power. Since TRP is an ‘isotropic’ value the antenna gain is also an ‘isotropic’ value and is called Total Isotropic Gain (TIG) and is expressed in dBi.

The TIG is also a measure of the efficiency of the antenna: it depicts the amount of energy that is radiated compared to the amount of energy that is supplied to its input. Due to losses in the antenna the TIG is always less then 0dBi.

The TIS can then be calculated by applying the TIG to the sensitivity of the receiver. When the sensitivity of the receiver is known (measured) and the TIG is known (calculated from TRP) the TIS can be calculated by multiplying the sensitivity with the TIG:

  • TIG = TRP / Ptx, or in dB: TIG = TRP - Ptx
  • TIS = TIG * Srx, or in dB: TIS = TIG + Srx

TIG and TIS derived from TRP

TIG and TIS can be derived from TRP

Transceiver properties

For calculating the TIG and TIS the properties of the transceiver must be known. The transmitter power and the receiver sensitivity must be determined at a common point that carries both the transmit signal during transmitter operation and the receive signal during receive. An obvious point would be the common terminal of the antenna switch.

Transmitter power

The transmit power is normally specified in the datasheet but is it better to measure it at the common measurement point. This is easily measured with a spectrum analyzer or power meter with the transmitter at its operation level.

Receiver sensitivity

The receiver sensitivity is more involved to measure for several reasons. First of all one must have some test setup to determine the lowest signal that can be received by the receiver. For simple protocols this can be a test device that is programmed in-house or a chip evaluation board with software. For more elaborate protocols and modulation like Wifi or CDMA a commercial test set can be used.

Most receivers are capable of reporting the signal level at the receiver input in the form of a Received Signal Strength Indication (RSSI). This value can be retrieved directly from the receiver registers, or it can be reported back to the tester through the radio protocol.

The RSSI measurement of the receiver is often well documented in the datasheet and accurate to 0.5dB but the signal is specified at the receiver input pin of the chip or module. If a receive switch or other combiner is used externally then there is an attenuation between the common measurement point and the receiver input.

To be able to translate the RSSI level to the level at the common measurement point it is necessary to do a one- time conducted verification of the RSSI report against the actual input value. While it is difficult to verify the RSSI around the threshold level, because of the high attenuation requirements and leakage problems, it often suffices to determine the RSSI value at a much higher level. With two measurements for example at -40dBm and -50dBm the linearity of the RSSI value can be tested and the difference from the actual test level can be calculated. After this measurement the receiver should be trusted to report accurate RSSI down to the sensitivity threshold level and the calculated correction factor can then be used to convert the RSSI to actual input levels.

When the RSSI behavior is established it becomes quite easy to measure the radiated sensitivity with the device in its natural operation condition. There is no need to know the signal path over the air and through the antenna since the receiver level at the common measurement point is determined through the RSSI value of the receiver. There is no need for an anechoic environment and, if there are no interfering signals from outside, the sensitivity measurement can be done at the lab bench. It is enough to determine the RSSI value of the radiated test signal at the sensitivity threshold. This can be done by moving the device or the test antenna around to find a point where the signal is very low.

TIS measurement procedure

This summarizes the steps to get to a TIS figure:

  1. Measure TRP at a test lab or with an in-house system.

  2. Measure TX power with a spectrum analyzer. This needs to be done only once.

  3. Calculate TIG

  4. Measure RSSI correction with a known level. This also needs to be done only once.

  5. Measure Radiated sensitivity with an arbitrary test configuration.

  6. Calculate TIS

For measuring against certification standards these steps should be done carefully and possible error sources should be taken into consideration. It may be desirable to measure the TRP power at a test lab and perform the remaining steps in-house.

If the TIS must be measured repeatedly during design debugging and optimization, steps 1 through 4 could be done once so that only the sensitivity measurement needs to be repeated between modifications. As long as the antenna and wiring configuration is not changed significantly the TRP should remain quite constant.

In fact, if the goal is to optimize the sensitivity then it is enough to just measure the RSSI at the sensitivity threshold and optimize this. The whole TRP and TIG measurement can be omitted. But again the antenna configuration must not be changed during these tests, otherwise the RSSI numbers can not be compared to each other.

Error sources

The preceding sections assume a theoretical system. In reality there are several other matters that can cause errors in the TIS measurement.

  • Impedances. Different impedances between the antenna, transmitter and receiver may cause different power transfer than measured with 50Ohm equipment. If the transmitter and receiver impedance are close to each other then the signals have the same power transfer.

  • Split frequency. If the transmitter and receiver are using different frequencies for upload and download the antenna characteristics between the channels may differ significantly. This can be resolved if it is possible to measure the TRP or TIG at the receive frequency.

  • Antenna diversity. If the device is using antenna diversity one must make sure to treat the antennas separately by forcing the signal to either of the antennas.

  • Interference from environment. If the receive frequency is used by other nearby devices it will be impossible to measure the radiated sensitivity in the field. A shielded chamber or GTEM cell can be used to keep unwanted signals out.

  • Reflected noise. When a shielded chamber is used without absorbers it is well possible that noise from the device or cables is reflected back into the antenna and this raises the noise floor. The chamber must be large enough or anechoic to avoid this.

  • Varying noise levels. If a processor or other component has varying levels of activity the noise level can also change over time. It is advisable to measure the sensitivity several times or over a longer period of time.

Conclusion

The TIS can be derived from a TRP measurement and simple sensitivity measurements that can be performed in-house. This is very useful especially during development or problem solving because there is almost instant feedback of the sensitivity performance.

 

Visit the RMS-0740 page for more information how to measure TRP and Radiation Patterns

 

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info@megiq.com (MegiQ) Application Notes Mon, 16 May 2016 15:20:00 +0000
VNA Match function has adjustable components https://www.megiq.com/blog/item/47-vna-match-function-has-adjustable-components https://www.megiq.com/blog/item/47-vna-match-function-has-adjustable-components VNA Adjustable Matching Screen

The match calculator of the VNA software calculates one or more 'ideal' match circuits to convert a selected point on the Smith chart to the desired impedance, usually 50 Ohm. This results in an 'ideal' match at the selected frequency but this may give a very small bandwidth of the matched network. The circuit will also give non-standard values that must be approximated with E24 or other component series values.

VNA software 1.5.4 and later have an enhanced matching calculator that allows the user to adjust the values of the matching components. This facilitates tuning the components so that the resulting Smith diagram can go slightly 'around' the target impedance instead of going dead center. This can result in a larger bandwidth of the matched network. To assist in the tuning the software also shows the bandwidth of the network, the range with a return loss better than 10dB.

The figure below shows the retuned match circuit with the resulting characteristics.

MegiQ VNA Match screen adjusted

This software version can be downloaded from our resource page. The user can test these functions with the sample data that is included in the package, without having a VNA connected.

The VNA-0440e is a popular Vector Network Analyzer for developing wireless devices. Most people use it together with the MegiQ VNA Sandbox to get started right out-of-the-box.

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info@megiq.com (MegiQ) Application Notes Thu, 12 May 2016 10:20:12 +0000
Compact system measures Antenna Patterns, TRP without anechoic chamber. https://www.megiq.com/blog/item/45-compact-system-measures-antenna-patterns-trp-without-anechoic-chamber https://www.megiq.com/blog/item/45-compact-system-measures-antenna-patterns-trp-without-anechoic-chamber MegiQ RMS

The RMS-0740 consists of a turn table and a measurement unit and is optimized for measuring devices without the need for an anechoic chamber. A moderate lab space is sufficient to get accurate 3-axis radiation patterns and TRP calculation.

RMS-0740 Radiation Pattern

There are many wireless developers who don’t have the 200k+ budget for a conventional radiation test setup. They spend either too much time in range testing or too much money on test lab measurements. The RMS-0740 gives a true insight in the RF performance for a fraction of that budget and in just minutes. This greatly enhances the performance of the product and the customer satisfaction in the field.

Extensive testing and comparing with measurements from an anechoic test lab shows that the measurement accuracy of the RMS-0740 is in the same order as anechoic measurements.

The application software makes the measurement flow straightforward and includes storage and reporting of the results. Results can be presented in Field Strength, ERP and antenna gain. Total Radiated Power and other statistics are calculated from 3 rotations.

There is a light weight turntable for small products and a heavy duty table for larger devices. Devices can be measured standalone in constant carrier mode, and a separate generator output allows for full characterization and frequency sweep of custom antennas and prototypes.

The measurement unit has a dual channel receiver that allows measuring two polarizations in one rotation. This cuts test time in half. A 3-axis measurement takes less than 2 minutes!

Visit the RMS-0740 product page.

Read the article "Calculating TIS from TRP" that explains how to use TRP measurements for TIS calculation.

MegiQ develops low cost T&M tools for RF development up to 4GHz. Their VNAs and Calibration Kits are used throughout the wireless development community.

 

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info@megiq.com (MegiQ) Application Notes Wed, 11 May 2016 13:43:38 +0000
MegiQ API brings budget VNA to factory testing https://www.megiq.com/blog/item/44-megiq-api-brings-budget-vna-to-factory-testing https://www.megiq.com/blog/item/44-megiq-api-brings-budget-vna-to-factory-testing MegiQ VNA data in Excel

For example, the API can be used for measuring S-parameters of components, antennas or RF systems during production. The controlling software can compare the test results against the specification limits of the EUT. By controlling the built-in Bias generator of the MegiQ VNA-0440e the software can also test the EUT at different operating conditions. All VNA parameters can be used in nested sweeps for maximum measurement throughput.

The API allows using preconfigured measurements and calibrations and it also provides functions for logging production data. There is a complete arithmetic set of functions that operate on whole measurement datasets at the time. Parametric (nested) sweep data is fully supported as a hierarchal dataset.

The API can be used under most popular programming languages such as C#, C++, LabWindows/CVI, VB and VBA for MS-Office. There are example programs in several languages to get quickly up to speed.

MegiQ develops low cost T&M tools for RF development up to 4GHz. Their VNAs and Calibration Kits are used throughout the wireless development community.

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info@megiq.com (MegiQ) Application Notes Wed, 03 Feb 2016 00:09:29 +0000
Using contactless antenna measurement in a production environment https://www.megiq.com/blog/item/41-using-contactless-antenna-measurement-in-a-production-environment https://www.megiq.com/blog/item/41-using-contactless-antenna-measurement-in-a-production-environment Antenna test fixture in use at Honeywell

RF antennas and tolerances

RF antennas are components that are by nature very susceptible for their environment. That is what an antenna got to do after all!

But here is a draw back to this: the performance, especially the resonance frequency, of an RF antenna can be greatly influenced by batch to batch tolerances of the PCB material and components, like capacitors, inductors and ceramic antenna. PCB material turns out to be a recursive problem for many of our customers because putting very tight tolerances on the PCB-production process and materials is very expensive.

Most of the time all goes well, and then suddenly the yield in a new batch of products can be too low. This is not very nice to encounter after you've assembled 10k+ boards! If you've had known all this in advance, you've could have tackled the problem by just changing that one small tuning capacitor.

Feed forward i.s.o. throwing away

MegiQ AN103 Test in production

MegiQ worked with Honeywell to tackle a problem with antenna yield. Although the design and production processes at Honeywell are very well controlled, for a particular design they had to make a trade-off between paying for tight tolerances or having the chance to have more rejects in a batch every now and then.

The idea is to measure the resonance frequency of the on board antenna at a low sample size prior to make the big run. In first instance that was done at assembled boards, but later on it appeared that in many occasions this could already be done on bare PCB boards. Almost every on-board antenna needs some kind of matching and after determining the influence of one of the matching component(s) on resonance, it turns out to be very simple to predict the right value once you measure the actual resonance frequency of the antenna on the bare PCB before assembly of the boards.

Most of the time that would be the value that had been designed during R&D. Just a few times a year they have to change the value of just one reel of capacitors on the P&P machine.

Et voilà, high yield at low cost!

Contactless measurement

We described the contactless measurement in a previous article. The idea came from using the old grid dipper. That is an instrument that can measure resonance frequencies of passive circuits. This is done by coupling the field generated by the instrument into the field of the passive circuit. Thus it is completely contact-less. As long as you do not couple too tight, you do not influence the system under test.

Grid dippers are outdated, read-out is difficult and they are not accurate enough for the purpose we are aiming at now. But a VNA would be a very nice instrument if you would combine it with a fixture that would couple one port of the VNA with the antenna on the board under test.

The coupling is done with a non-resonant induction loop. The size and the placement of the loop depends on the frequency and the topology of the antenna and PCB. This is not one size fits all, you will need a fixture per type of product anyway, because it is very unlikely that all dimensions of the PCB of all your products are the same.

MegiQ AN103 Return loss dip

Test fixture

MegiQ designed and printed a very simple test set-up for Honeywell in their production process of wireless climate control products.

Until now MegiQ has designed and produced several test fixtures with pick-up antenna for this purpose that allow reliable measurements on several types of antennas, Loops, monopoles, dipoles, PIFA on all kinds of bands. However, not all antennas and designs are suited for this technique.

MegiQ AN103 Testfixture open

If you would like do design your own fixtures, take care of the following points:

  • the self resonance of the pick-up antenna should lay well away from the frequency of interest
  • make the coupling mechanically stable, and do not couple too tight.
  • do not influence resonance by nearby objects, like the fixture itself.
  • beware that the enclosure of the end product will also influence the resonance frequency, so take this into account.

You can also outsource this design to us. Of course we need your product to be able to design the fixture.

software

When just checking a few samples every batch of new PCB's, you can just use the user interface software that comes with the MegiQ VNA. It is very handy in use, you can store the complete settings of the instrument inclusive calibration, and recall the right setting for every one of your products. The system remembers also markers, so readout is easy.

But if you want to collect data on many boards, you can completely automate the process, by using the API that comes with the VNA and writing your own application. If you want with Go/NoGo decision making and interfacing with the production line.

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info@megiq.com (MegiQ) Application Notes Fri, 15 Jan 2016 21:01:00 +0000
UFL Connectors in VNA Measurements https://www.megiq.com/blog/item/40-ufl-connectors-in-vna-measurements https://www.megiq.com/blog/item/40-ufl-connectors-in-vna-measurements UFL Connectors in VNA Measurements

Component quality

When preparing a VNA measurement the focus is often on the quality of the components of the setup, like cables and connectors. But this often leads to bulky parts that inhibit the use of the test setup in real life applications like measuring a 2450MHz printed antenna on a small sized PCB.

MegiQ Antenna Diversity UFL

Although a good quality SMA-connector would probably be your first choice, for really measuring the antenna, without disturbing the circuit too much, MegiQ suggests a far smaller connector to be used. Even if this does not have the same high level specifications.

Integral quality

MegiQ proposes the use of UFL (small) or WFL (ultra-small) connectors so that you can design in the footprint for the measurement points without getting a bulky PCB. This way you get measurements that by far exceed in accuracy over measurements done in the old style. Credo is: "Do not try to shoot a mosquito with a canon."

Of course, using these connectors should be done with care, and good calibration tools are needed.

This way you do not sub-optimize on component (connector) level, but integrate quality over the scope of the whole set-up, meaning: taking the Device Under Test into account!

No overkill

Overkill can lead to bad measurements, even though you would think the other way. A comparison: Many people think a Ferrari is a better car then a truck, but if you want to move 20 tons, you better choose for the truck!

MegiQ engineers are designers of RF-circuits too. We've learned our lessons in real life. And we found that being inventive and thinking out-of-the-box really pays back!

Using UFL has a lot of advantages:

  • UFL will do! Most applications do not need an insertion loss over 25dB. Do not lose your time in over-optimization.

  • It is low cost, after 100 times mating you just take a new cable /connector. Wearing out is also a problem with the "better" (end very expensive) high-end connectors! They lose their reliability too... Without you knowing it.

     MegiQ AN101 ContactGrease

  • UFL is small, you can design-in the test-connector on your PCB for optimal and repetitive accuracy.

  • You will get better measurements that you would not get with bulkier connectors. Because of the simplicity in using the small UFLs you do not change the topology of the PCB, the footprint is already there. This increases overall end-product quality.

MegiQ Sand Box

A good example using UFL for testing purposes  is the MegiQ Sandbox , an evaluation board with 26 instructive circuits, including two antennae and an OSLT calibration kit.

MegiQ AN102 VNA sandbox

For connecting the circuits under test to the VNA this PCB holds 37 UFL connectors on a 105x75 mm (4.1x3.0") surface. And there is still enough space left to build a complete phone on the PCB!

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info@megiq.com (MegiQ) Application Notes Thu, 14 Jan 2016 17:06:00 +0000
Contactless antenna measurement using a Vector Network Analyzer https://www.megiq.com/blog/item/43-contactless-antenna-measurement-using-a-vna https://www.megiq.com/blog/item/43-contactless-antenna-measurement-using-a-vna Contactless antenna measurement using a Vector Network Analyzer

Antennas are made to interact with their environment and this makes it possible to couple externally to the antenna and measure some properties.

There are two types of antennas, electric (dipole, whip) and magnetic antennas (loop, slot) and we need a different probe for each of these types. Electric antennas are difficult to couple to but a magnetic probe is quite straightforward.

Magnetic probe

We can use an inductor to couple the magnetic RF field to the VNA. It is necessary to use an inductor with a fairly large surface to couple to an antenna, while at the same time the inductance needs to be such that it presents a reasonable impedance to the VNA, in the order of 50 Ohms.

The inductor is connected to the VNA and we sweep the return loss. It is not really necessary to perform a cable calibration when the VNA has port calibration.

MegiQ AN105 TI Pulse antenna

By itself the return loss measurement is not very interesting as it shows the value of the inductor (and its cable). But, if we approach a (loop) antenna a dip starts to appear in the return loss graph. This dip marks the resonance frequency of the loop antenna.

The Smith chart shows that the probe by itself is inductive (near the upper edge of the top half circle), but that the antenna pulls the impedance toward the center (50 Ohms) at its resonance.

As we get nearer the antenna the dip will get deeper but at some distance it also starts to shift, either upwards or downwards. This is because our probe starts to affect the frequency of the antenna. We should keep the distance where the dip is visible but the antenna is minimally affected.

MegiQ AN105 Contactless Smith

The graph was measured with a Pulse loop antenna on TI test board. The antenna is connected to the second port of the VNA only to verify that the actual resonance is the same as the ‘coupled’ resonance.

The original frequency, without the probe nearby, is 873MHz, so there is a shift of 5MHz to 878MHz in the antenna resonance.

Antenna types

The magnetic probe is well suited to couple to different variations of loop antennas and other magnetic antennas as long as we couple to the area where the current creates the electromagnetic field.

But the magnetic probe can also be used to measure a (electrical) PIFA antenna by coupling the probe to the ground loop of the PIFA while avoiding the tip of the antenna, as shown in the cover photo.

Contactless measurement

A good application of this technique is with (small) PCBs that are severely affected when a cable is connected for antenna measurement. In some designs there is a lot of ground current in too small a ground plane and it’s looking for a way out.

This current is affected by a VNA cable and the cable will participate in the radiation and alter the overall RF properties of the PCB. A ferrite choke around the cable can reduce this effect but the contactless loop measurement can be used to verify that the conducted measurement is valid. When the contactless measurement changes too much when the VNA cable is connected directly, then there is a severe effect on the PCB by the VNA cable.

Test fixture

For individual tests we can just approach the antenna and watch the dip getting deeper, until the point that it starts to shift. We can also use this test to check the antenna of a production series, but then a test fixture needs to be made to couple the probe consistently, so that the frequencies can be compared. The activity of the antenna can also be compared to others by comparing the depth of the dip.

MegiQ AN103 Testfixture open

The picture shows an 868MHz PCB with an Ethertronics Savvi loop antenna in the upper left corner. On the right is the loop probe in a 3D-printed test fixture.

Conclusion

  • With the contactless method we can get a quick impression of the frequency and activity (Q) of different kinds of magnetic antennas and some electric antennas that have a current loop in their feed.
  • The contactless measurement can be useful to measure ground-sensitive antennas.
  • This method is also suited for a production (pre-) test to quickly screen the antenna frequency.
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info@megiq.com (MegiQ) Application Notes Tue, 12 Jan 2016 21:00:00 +0000
Wireless Luminaires https://www.megiq.com/blog/item/42-wireless-luminaires https://www.megiq.com/blog/item/42-wireless-luminaires Wireless Luminaires

Luminaire Designers Nightmare

The ultimate nightmare for the Luminaire Designer is a real estate project at the other side of the world, with thousands of luminaires, all mounted high at the ceiling...
Where some 5% of them do not work every now and then.

You do not want to go around repositioning the (fixed) luminaires for getting good results. And most likely the units will have been installed by an other company, by people you do not know and in premisses of which you cannot get the details. A company that will not be pleased with the performance and you'll never know for sure whether or not the installation instructions have all been properly followed.

Predicting Wireless Performance

Let's be honest: “Wireless Real Life” is far too complicated to model it in a simple way, if modelling it in any reliable way is possible at all!

This not only applies to installing the luminaires in a building. It all starts with the design of the luminaire itself for RF-performance, given a certain RF-module!

Giving design rules and measurable limits for a set of parameters to insure e.g. 99,5% reliability in the field, is impossible without (expensive) over-specification.

A good RF-designer is worth it's weight in gold, because he or she has acquainted him/herself with many of the unpredictable influences surroundings have on wireless communications.
But there are very few of them around, RF is not a very popular specialisation, it is not very easy to learn and takes years.

That's the reason that you'll find so much sense and nonsense around RF. Some is pure lore, other is based upon observations that are valid for one specific case only.

"So what's the Problem...?"

Let's get more specific about the problems the Luminaire Designer faces: He or she has a lot of knowledge of lighting, mechanics, fabrication technology, industrial design and lifestyles, colour schemes, safety standards, etc.

Yesterday´s electronics that were integrated in the luminare's design were often plug and play because it used wired networks. A lot of work to install the luminaires in the building, but when done correctly, it simply works. And if not, the unit was defective.

With the coming of RF this all changes. You can have a perfectly working RF-module, and having no/communication at the same time in the field.

MegiQ AN104 Luminaire

Price and aesthetics ask for “No Antenna” and “hiding the electronics” but the laws of physics ask for radiation i.e. visibility of the waves in order to establish communication.

This paradigm looks like wanting to hide the lamp bulb away and still asking for the best visibility. Remember: radio waves are the same as light waves.

Yes it is possible to find a good, working trade-off, but you really must know what you are doing!

What influences RF Bahaviour

Even given a well designed RF electronic module, still a lot influences network performance in the field, like:

  • Way of mounting the RF unit in the luminaire

  • Shape of the luminaire

  • Wiring ín the luminaire

  • Materials of the luminaire

  • the positioning of the luminaire in the field

  • When mounted in the ceiling, the material of the ceiling, height,
    material of the floor beneath, etc.

  • Inventory in the room where the luminaires has been placed (chairs, cupboards, tables, ...)

  • On greater distances: the relative humidity of the air (specially at
    2.5 GHz)

  • And so on ...

RF, a Way of Life

RF is so different from what we were used to. It looks like “a way of life'... It asks for a different attitude towards the design cycle. Best is to start looking at the RF properties as early as possible in the design phase. Since geometry, materials, all influence behaviour.

  • Work together with the artist that designs the 'looks' of the luminaire. Start in an early stage of the design cycle!

  • Gather information from beta test sites and establish your own standards for radiation patterns, transmitted power and receiver sensitivity based on measurements on your luminaires and statistical data on performance

  • Measure, measure, measure... do not guess! This applies for:
    - Antenna impedance and matching.
    - 3D radiated power / radiation pattern
    - TRP (total transmitted power)
    - 3D receiver sensitivity

  • If you are designing several luminaires a year, investing in a set-up to measure 3D patterns and radiated power will pay itself back very fast.
    From doing the measurements you will get a lot of hands-on training and practical RF-expertise.

  • Measure the radiation performance of a mock-up of the luminaire in an early phase. Try different solutions. And try to use materials for the mock-ups that come close to the final design.

  • Experiment with different solution...
    Not just to design a product, but in first instance to learn! Remember, RF is probably new to you. You need no to become an antenna expert, but you'll need some basic feeling and understanding.

  • Go for some consulting with an engineering house specialized in RF. And... make sure you learn from them!

  • Choose the RF-module with care. Not only on paper. Test them, try them!

  • And of course, read carefully the instructions that come with the RF-modules you are using in your design.

Radiation pattern

There is a tendency to specify the needed TRP (Total Radiated Power) Of course this is important, but far more important is to know the radiated power in the wanted direction! This asks for measurement of the Radiation Pattern along the three axis. And of course you knowing what the preferred radiation pattern would look like.

Think of a luminaire for lighting along highways. The luminaires are some 50 m apart, mostly in a straight line and they can actually 'see' each other. Energy radiated up or down will get lost, and you probably would like to have the radiation pattern in the shape of a discus.

An other application, e.g. luminaires for offices, is better of with an omnidirectional radiation pattern, making use of the many reflections in most offices.

Some Rules of the Thumb

It is impossible to give a set of design rules that will guarantee a good design RF-wise. Designing in antennas in luminaires is more an Art & Craft then rocket science.

Rules of the Thumb if combined with some basic understanding are far more useful than equations and computer models.

So here some things to take into account:

  • Choose the network topology with care, e.g. Star or Mesh. This greatly depends on the application in the field!
    This has of course to do with the module you are going to use.

MegiQ AN104 Star Network

Star network

MegiQ AN104 Mesh Network

Mesh Network

  • Metal enclosures can shield RF energy. If you use metal in your design, make sure the RF energy can come out. That can be done by holes and sleeves of the right size and position. Dimensions and placing of these holes can be very critical.

  • Mounting an antenna near metal objects can severely influence antenna performance, radiation pattern, a.s.o

  • Metal sheet can act as a reflector, focussing RF energy more or less in one direction. The direction also depends on the distance of the antenna (in the module) to the metal.

  • Mounting an antenna near to an insulator, like plastics and ceramics, can influence antenna behaviour.
    It lowers the resonance frequency which can cause mismatch of the antenna to the electronics.

  • Measure 3D antenna radiation patterns and look for dead spots in the diagram. Avoid 'blind spots” in the radiation pattern, because they will hamper reliable communication.

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info@megiq.com (MegiQ) Application Notes Thu, 07 Jan 2016 21:17:00 +0000
Taking Care of Connectors https://www.megiq.com/blog/item/39-taking-care-of-connectors https://www.megiq.com/blog/item/39-taking-care-of-connectors Taking Care of Connectors

Mating cycles

The amount of mating cycles depends on the type and quality of the connector and of course of the reliability you expect of your measurement.

MegiQ AN101 UFL size

For SMA it is specified at several hundred times, for UFL & WFL this is much lower, somewhere between 20 and 50 times. But if you take good care 100 times is a good average, and if you take care while calibrating you will often notice when the UFL has reached its end of life. Luckily, these UFLs are inexpensive.
Our experience is that the cable part of the connection wears down much faster than the PCB-mounted part.

Most connectors you can change for new ones once worn down, but this does not apply for the SMA on the front panel of your VNA. Therefore try to limit as much as possible the times you (un)screw these SMA connections.

MegiQ AN101 Lifesaver

You can make use of SMA-savers (“life-savers”), i.e. an SMA male to female adapter you screw on the unit to leave it there. If you need to change this rather inexpensive adapter e.g. every 500 times, and the same amount applies for the SMA on the unit itself, you will wear the connector on the front panel down only after 500x500 = 25,000 times.

Use a SMA to UFL adapter for this if you work with UFL and leave the adapter on the frontpanel!

Damage

It is easy to damage most connectors, even unintentionally. Therefore always look well at what you are doing and align plug & jack very well before mating! Use glasses if you cannot see it well, UFL and specially WFL are very tiny connectors!

With connectors with a screw, like SMA and N, be sure to only turn the screw while holding the inner part of the connector still. Thus you will not cause friction that wears down the RF-parts of the connector excessively.

Also take care when unmating UFL or WFL: Make the movement “in line” with the pin, so perpendicular to the PCB. Do not “peal the plug off” by tearing at the cable.

Any connector: do not use defective connectors! They damage the jack you mate it with. So carefully inspect connectors for damage before using, and discard defective ones!

Especially for SMA connectors: inspect the center pin for damage or ill-formed shape. If it is not a smooth cone, do not use it. And, very important, feel how the mating goes. DO NOT continue screwing and DO NOT use a wrench if it doesn't feel right. Chances are that you are in the process of ruining the female center contact!

Lubricant

It is a good idea to use a lubricant, specially made for contacts, but be sure to use a type that does not affect contact characteristics of the connectors. A lubricant makes a lot of difference when using UFL-connectors.

MegiQ AN101 ContactGrease

We've got good results with contact grease in a small dispenser, much more handy then a spray. The latter will easily contaminate a big area of the PCB.

Warranty

The MegiQ policy is that all connectors are “wear down items” and do not fall under warranty.

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info@megiq.com (MegiQ) Application Notes Tue, 05 Jan 2016 17:02:00 +0000