Impedance Matching with QUCS Studio and VNA

Intro

In my last blog post I alluded to the fact that you could take s1p touchstone files generated by nanoVNAsaver and use this to automatically calculate/simulate a matching network in QUCSstudio. This could be used to quickly design antenna matching networks for instance. I was asked in the comments about exactly to do this. Of course, I had totally forgotten!!! But lets go through it again.

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Getting Started with the NanoVNA -Part 3 – PC Software

VNA Saver – PC Software

There is now a variety of PC based software that is available to use with your nanoVNA. In this post, I will be demonstrating NanoVNASaver(version 0.0.9). This is developed by Rune Broberg and is fully open source. Rune originally developed the software as a way to save Touchstone files from the NanoVNA to use in other programs, but couldn’t resist expanding it’s functionality into what is now a fairly complete PC app to run the NanoVNA. If you want to participate in conversations with Rune, He is active on the groups.io nanoVNA group which is an excellent place to find all the latest tips and experimental firmware builds etc. https://groups.io/g/nanovna-users

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Getting Started with the NanoVNA -part 2

In the previous post, we got up to speed with the basics of what a VNA is and how to run a basic calibration. In this post we will look at configuring the traces and formats.

Note on Charging – One note, before we go deeper. My NanoVNA doesno like to charge from my PC USB type C port or my Samsung Quick charger. Use a regular USB-Type-A from an less intelligent charger and it’s fine.

Configuring Traces, Channels and Formats.

Throughout this guide, I will assume you are using a stylus(or your finger) to control the NanoVNA via the touchscreen. You can of course use the rocker control to perform all these applications. Read more ›

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Getting Started with the NanoVNA -part 1

This post now includes some edits based on user feedback[in green italic]

What is a VNA?

The Vector Network Analyser is an essential piece of test equipment that no RF engineer should be without. If you have previously worked with Electronics at low frequencies, you may consider a good DMM or Oscilloscope your best friend. RF Engineers would gladly trade both a scope for a good VNA!

A good VNA is an expensive bit of kit. Many years ago, a good one would probably cost you as much as a fairly nice house. Nowadays, you can pickup something really good for the price of a nice car. Note, High-end VNAs can still sell for between $100K and $1M. I will use the term ‘professional┬áVNA’.

carorVNA

“What’s it’s dynamic range again?”

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Spiral Antenna – Part 3 – Results and Suckers

In the chamber

Antenna in Test Lab

The original aim for this antenna was to be a general purpose antenna that worked down to 400MHz. The results are now in and I am really pleased with them. The antenna was tested by AntennaTestLab in a full anechoic chamber with a 3D positioning system to automatically rotate the antenna. ATL use a dual polarized (horizonal and vertical) Vivaldi antenna to measure the radiation pattern. By recording both the amplitude and phase of each antenna they can use clever math to calculate the circular polarized gain. Clever stuff eh?! Take a look at ATL’s writeup here

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Spiral Antenna – Part 2 – Modelling and Simulation with OpenEMS

Now tested by AntennaTestLab. For now see results here

Electromagnetic simulation software can be very expensive. While some software is cheaper, it often comes with either technical or artificial limitations. There are however a couple of free alternatives.

NEC2 – Originally written by Lawrence Livermore National Labs, NEC2 was open sourced many years ago. Since then a couple of users have created good free or low cost front ends for it. 4NEC2 is my personal favourite. The best feature is it’s speed, especially if you can find a copy of NEC2/MP that makes good use of multiple core moderns processors. The big limitation is with dielectrics. Everything in NEC2 is either wire, free-space or earth.

OpenEMS – A Finite Difference Time Domain (FDTD) tool that uses MATLAB or the excellent free Octave as a front end. It was created by Thortsten Liebig at the General and Theoretical Engineering University in Germany. As suggested in FDTD, OpenEMS uses a time-domain approximation of Maxwells equations to calculate the results. The big advantage of OpenEMS over NEC2 is that it can handle bulk dielectric materials with different EM properties, I will need this to simulate an antenna on FR4 with an Er~=4. While it may not seem it at first, being able to generate geometry mathematically in is another advantage. This is especially true for a spiral antenna. Hence this is the package I decided to learn and use for this project.

Dont Panic!!!

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Spiral Antenna – Part 1

Why?

My original Palm Tree Vivaldi Antenna has proved amazingly popular. Much more so than I originally intended. The design aim for this was primarily for it to be small and portable.

When deciding what to do next I decided to create a survey and see what other people were interested in.

Survey

R&D Survey Results

The overwhelming response was that people wanted a bigger version that would cover lower frequencies. I can understand this, there are loads of interesting signals below 800MHz.

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Reconfigurable Ultra-Wideband Antenna Array Kit – part 2 (Spacing)

Why Spacing Matters

Firstly, the antenna array I am designing is a fixed in-phase array. Hence we assume that the total path length from each antenna to the single input/output connection are the same length. This makes the design and analysis much simpler, especially for an ultra-wide-band design.

In my design signals that arrive at right angle to the antenna will add up co-herently (in-phase)

spacing boresight

Signals arriving from boresight add up in phase

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Ultra-Wideband Antenna Lab Measurements

Palm-Tree-Antipodal-Vivaldi-Antenna-Anechoic-Chamber-Photo-3

Antenna being tested in anechoic chamber

My Vivaldi Antenna was recently tested by Antenna Test Lab who offer an excellent professional antenna testing facility. Antenna Test Lab are able to provide customers with full 2D/3D antenna measurement using their anechoic antenna testing chamber. Read more ›

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UWB Antenna R&D Survey

I am conducting a quick survey to help discover what developments people would most like to take my UWB antenna forward. I would be really grateful if you could take a few minutes to have your say.

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