Antenna theory/design resources?

[Blaise]

So I've been building a huge list of questions about how antenna layouts might work, and I've realized that onesie-twosie answers are always going to leave me wondering about the next thing, and annoy the folks I pester, so what I really need to do is go back to school. 

 

Anyone have recommendations on how to teach myself to fish in the sea of antenna theory and practice?

[SteveShannon]

Probably the best way is to pick up something like the ARRL Antenna book and then watch some videos that teach the use of EZNec or MMANA, which are two antenna modeling programs.  Free versions of each are available and they’re pretty easy to use.  Look for a channel on YouTube by DX Commander that has some tutorials on MMANA or David Casler on EZNec.

I would try going to a ham swap meet and getting a used copy of the book; it’ll cost much less than ordering from ARRL and the difference will be minimal.  Antenna theory hasn’t changed much lately, except for the gigahertz regime.  There haven’t been any landmark discoveries that have changed people’s minds for awhile.

I receive a big book quarterly of the Transactions of the Antennas and Propagation Society of the IEEE and I almost freeze at the titles of the articles. I think I’d have to go back to school just to understand the titles, much less the actual articles, but every article is about gigahertz or terahertz uses.  As far as I can tell the UHF stuff is relegated to the same dusty shelf as VHF, and HF.  There’s probably something still being done for ELF also, but I haven’t seen anything.

[Lscott]

7 hours ago, Blaise said:

So I've been building a huge list of questions about how antenna layouts might work, and I've realized that onesie-twosie answers are always going to leave me wondering about the next thing, and annoy the folks I pester, so what I really need to do is go back to school. 

 

Anyone have recommendations on how to teach myself to fish in the sea of antenna theory and practice?

Try reading this book. It's written for the average Ham Radio operator so it doesn't get crazy with the math etc.

http://www.w3pga.org/Antenna Books/Reflections III.pdf

[KAF6045]

10 hours ago, Blaise said:

Anyone have recommendations on how to teach myself to fish in the sea of antenna theory and practice?

How theoretical did you want.

As mentioned, the ARRL Antenna Book is probably a first resource. You just have to rescale things for 465MHz as most UHF example antennas will be sized for 440MHz. The overall concepts of gain, etc. would be covered.

Real theory? Antenna Physics: An Introduction gets rather crunchy.

For designing/optimizing: Antenna Modeling for Beginners (covers usage of EZNEC), An Introduction to Antenna Modelling (focuses on MMANA-GAL).

And, if you end up creating some serious gain antennas RF Exposure and You covers the safety aspects, calculating safe distances from the antenna to "controlled environment" (those who know there is a transmitter in operation and can take actions to minimize exposure) and "uncontrolled environment" (neighbors, people on the street, etc. who don't know about and can not control their exposure to your transmitter).

While all the above are available from the ARRL, the MMANA-GAL book is actually from RSGB.

For software: the creator of EZNEC has retired, and made EZNEC PRO v7 a free download but offers no support https://www.eznec.com/ . The RSGB book DVD provides a version of MMANA-GAL the current version is http://gal-ana.de/basicmm/en/ (the Pro version is 140Euro for personal use license). 4NEC2 https://www.qsl.net/4nec2/ is a somewhat cruder package -- it explicitly uses external NEC-2 executables built for different memory usages (number of wires/segments). I believe it basically started as an Excel macro package for editing NEC-2 command cards and grew into a stand-alone GUI for NEC-2 (if you are a glutton for punishment, you can download the NEC-2 manual and hand edit the Hollerith card type input deck it uses -- EZNEC and 4NEC2 both use the NEC-2 engine for number crunching [unless you fork over a fortune for a license to NEC-4 from Lawrence Livermore National Labs -- hmm, there is now a NEC-5, wonder if it would be compatible with EZNEC]).

Given that EZNEC Pro is now free, I'd probably start with it as the books that include datasets for models probably use EZNEC input files.

 

[Blaise]

Thanks, folks.  I've got The ARRL Antenna Book, 23rd Edition (all 1000 pages!) and Reflections III.

Looks like about three months of reading.

Well, I asked for it!

[Lscott]

16 minutes ago, Blaise said:

Thanks, folks.  I've got The ARRL Antenna Book (all 1000 pages!) and Reflections III.

Looks like about three months of reading.

Well, I asked for it!

The next thing you're going to want is a good antenna analyzer. There are lots to choose from. Seems the favorite is a VNA, vector network analyzer. Be careful which one you buy. Some are using crappy components, poor PCB layouts and generate poor results.

  https://nanorfe.com/nanovna-v2.html

[Blaise]

39 minutes ago, Lscott said:

The next thing you're going to want is a good antenna analyzer. There are lots to choose from.

I already have a nanoVNA v4.  I needed it to sort out issues with my car antennae.  Now I'm trying to figure out antenna placement for a base station, along with how it will interact with nearby antennae, and potentially buying a repeater (and maybe building a mobile one from HT's).  It turns out that the number and complexity of the questions you need answered increases exponentially with the number of things you are trying to do!

[Lscott]

An in-band repeater you likely need a good cavity duplexer. Tuning one isn't so easy with the inexpensive VNA's since they lack a high dynamic range. 

The attached files are from my on-line library I keep on the computers and smartphone for quick easy reference. For duplexers this might prove useful.  

Calculating Required Isolation.pdf 468523097_RepeaterAntennaSystems.pdf Understanding Maintaining and Re-Tuning Antenna Duplexers.pdf