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Comment by rfdave | Hacker News Reader

You're trying for a huge breadth of material, stuff that is covered in multiple specialities in electrical engineering. Multivariable calculus is really the entry point for engineering level antenna design.

Balanis is the book I used in my antennas class, https://www.amazon.com/Antenna-Theory-Analysis-Constantine-B... but you'll need multivariable calculus to get through it.

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Balanis' book is a great reference but I wouldn't recommend it for learning. Honestly the ARRL antenna book and antenna handbook are the best practical books on putting an antenna together without getting bogged down in the details. The real hard part is getting some radio equipment so that you can experiment and learn since Spectrum and Network analyzers are waaaay out of most people's hobby budgets.

True. I already own a Baofeng, and an SDR, but for the rest I'm honestly thinking of using my Arduino in conjunction with some diy circuitry (if I can wrap my head around enough of it) to build an oscilloscope, and I found an article that used a noise generator in conjunction with an SDR as an SWR meter [0]

It's definitely not high end, but my wife would kill me if I she found out how much I'd have had spent a halfway decent SWR meter, if I went that route.

[0]: https://www.rtl-sdr.com/rtl-sdr-tutorial-measuring-filter-ch...

I bought a $20 oscilloscope for fun and learning, called a DSO 138. Probably not suitable for antenna stuff though.

You could also try a local hack space, if you have one. My local one, Vancouver Hack Space, has some very fancy oscilloscopes.

Not a bad idea but a few things to keep in mind. - The sample rate on an Arduino is pretty low, depending on which model you have it may only be a few MHz and the absolute best you can theoretically possibly achieve with your home o-scope bandwidth is half the Arduino clock frequency. You'll also have to cast off the Arduino language and start moving to C/assembly to get the full performance out of it. -The dynamic range on the Arduino ADCs is pretty low. It's going to be limited by the number of bits in the Arduino ADC. -The input on an Arduino ADC is going to be either very low or very high impedance. This is also common on lower frequency scopes (low frequency in the case being 1GHz or less bandwidth) but if you try driving your input directly the impedance mismatch from the RF is going to cause poor signal and lots of noise on your measurement.

I don't know what SDR you have but it might be suitable for the signal capture and you can probably gin up some filters in post processing to approximate a Spectrum analyzer. If you have a source and 2 directional bridge couplers you could use it to make a poor mans Scalar Network Analyzer. A noise generator or a swept tone (Chirp) can be used in both these cases. The article you linked basically did a 1-port Network analyzer using the bridge coupler and used to to measure VSWR.

A lot of modern oscilloscopes, even hobby ones, now include the ability to capture scope traces to a PC and an FFT math function. You're going to be limited in frequency without a downconverter but it's a good way to go on a budget when working on a bench. The Rigol's are a lot better than they were when they first came out and make a good hobby scope for a reasonable price. If you can be spendy, the Keysight hobby level scopes are a joy to use. Best bet on a budget is to troll the internet for an old Tektronix, Lecroy, or HP/Agilent/Keysight but you'll probably not get something with fast trace capture or a built in FFT.

All of that said, making test equipment out of your Arduino is a great hobby project that will teach you tons of useful engineering. I highly recommend it!

I had Stuzman and Theile in antenna class, but Balanis for grad level EM.

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