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Matrix Switch for use with 75 Ohm Network Analyzers

75 Ohm Matrix Switch

Three new 75 Ohm blocking matrix switch models have been added to the JFW website.  Model 75MS-029 is a solid-state 2X8 blocking matrix that operates 3-1000MHz.  Model 75MS-030 is a solid-state 2X6 blocking matrix that operates 3-1000MHz.  Model 75MS-037 is an electro-mechanical 2X12 blocking matrix that operates DC-1700MHz.  These 75 Ohm matrix switches can be used to fan-out connections from a 2-port 75 Ohm network analyzer to allow for automated multi-port 75 Ohm testing.  Connecting the 2X12 matrix in series with a 2-port network analyzer, creates a twelve port test set.  For all three models, the unused output ports are self-terminating at 75 Ohm impedance to keep the DUT properly impedance matched at all times.  All three models are remotely controlled via serial or TCP/IP connections.  The remote command set consists of simple ASCII formatted commands.  The remote command set for our 3.x.x firmware is available for download.  If you have any technical questions about these 75 Ohm matrix switches, please contact our engineering department for assistance.

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Identify a 2.9mm Fixed Attenuator from 2.4mm Fixed Attenuator

SMA, 2.9 mm, 2.4 mm RF connectors

With the push to 5G by wireless cellular providers, lab benches are now being occupied with a greater number of high frequency fixed attenuators with 2.9 mm (aka 2.92 mm) and 2.4 mm RF connectors.  It is important to be able to tell these RF connectors apart because 2.4 mm and 2.9 mm connectors will damage each other if mated together.  2.9 mm connectors operate up to 40 GHz.  2.4 mm connectors operate up to 50 GHz.  There are notable visible differences between SMA, 2.9 mm and 2.4 mm connectors.  SMA and 2.9 mm connectors can be mated to each other without causing damage.  Their connector threads are identical and their male/female pin diameters are mechanically compatible.  The obvious difference between a SMA female and a 2.9 mm female is the dielectric.  SMA female has PTFE dielectric and 2.9 mm has an air dielectric.  2.4 mm connectors are not compatible with SMA or 2.9 mm.  The 2.4 mm connectors have a different thread and male/female pin diameters are 56% smaller.  The RF specifications for fixed attenuators that work up to 18 GHz, 40 GHz, and 50 GHz vary greatly.  The RF specification differences can be seen with these three low power fixed attenuator models:  50HF-xxx SMA (DC-18 GHz), 50HFAR-xxx 2.9mm (DC-40 GHz), 50HFAT-xxx 2.4mm (DC-50 GHz).

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Power Divider/Combiner Types and Functionality

This application note covers resistive and reactive power divider/combiners.  The main goal of this app note is to help customers choose the correct power divider/combiner type for their application.  The functionality differences between the two types are discussed with example block diagrams.  The block diagram makes it easy to see why resistive divider/combiners are used for military radio testing.  The block diagram for reactive power divider/combiners shows how its construction is better suited for the fan-in or fan-out of RF signals to multiple devices.   If you have any questions, please contact our engineering team for assistance.

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RF Matrix Switch Types and Functionality

This application note discusses the four different construction types for RF matrix switches with pros and cons for each type.  Matrix switch types discussed:  blocking matrix switches, non-blocking matrix switches, super non-blocking matrix switches, and common highway matrix switches.  The functionality of each construction type is discussed with example block diagrams.  Please contact our engineering department directly if you have any questions or requests.

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Remote Command Syntax Testing with JFW’s Ethernet Test Box

Dedicated Ethernet Test Box at Fixed IP 96.82.36.45 port 3001

The number one FAQ we receive from customers about our remotely controlled test systems is “How easy is it to connect and control the test system?”.  So we setup an Ethernet test box that is accessible 24/7 for engineers around the world to try out.  It is running our latest 3.x.x firmware.  Connect to the test box via a telnet connection at fixed IP address 96.82.36.45 on port 3001.  You can use your own telnet program or one of our sample test GUI programs to communicate with the text box.  All of our 3.x.x firmware remote commands are detailed with examples in our 3.x.x firmware manual.  If you have any firmware or networking questions, you can contact our engineering department directly with questions.

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Understanding The Limitations of Modern Military Radio Testbeds

This application note discusses three different testing configurations that can be used to test military radios.  The test configurations are:  Hub Fan-out, Full Fan-out, and Limited Fan-out.  Each configuration has its own testing features and limitations which are discussed.  We do provide direct access to our engineering team if you have any questions or want testing recommendations.

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A Fixed Attenuator can Improve your Harmonic Distortion Test Setup

Typical harmonic distortion test setup:  Signal Generator, Low Pass Filter, DUT (device under test), Spectrum Analyzer.  The low pass filter is used to filter out any high frequency distortion created by the signal generator.  The low pass filter ensures that the fundamental test signal (Fc) is the only RF signal being input into the DUT.  However, this only cleans up the first half of your harmonic distortion test setup.  The other source of distortion that must be accounted for is the harmonic distortion cause by the front end of the spectrum analyzer.  Spectrum analyzers cause a substantial amount of signal distortion.  It must be accounted for before testing the DUT.  Because the distortion caused by the spectrum analyzer is in your testing band you can not use a filter to fix this problem.  Instead, use fixed attenuators.  Take the DUT out of the test setup.  We want to check the harmonic distortion level measured of just our test setup.  If you add a 10dB fixed attenuator on the front end of the spectrum analyzer and the difference between Fc and 2Fc increases, then you just improved your test setup.  Keep adding 10dB fixed attenuators until the difference between Fc and 2Fc stops increasing.  Now your harmonic distortion test setup has been optimized.

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