Looking for recommendations for a good Antenna book

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Discussion Overview

The discussion revolves around recommendations for books on antenna theory, particularly for someone interested in designing and building antennas for a restored valve radio capable of receiving shortwave broadcasts. The scope includes practical applications, theoretical understanding, and considerations for specific receiver types.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant seeks a comprehensive book on antenna theory suitable for undergraduate-level understanding to aid in building antennas for a valve radio.
  • Another participant recommends a specific book, suggesting it is ideal for home-brewing antennas and mentions the availability at local HAM Radio outlets.
  • There are discussions about practical antenna setups, including a long wire antenna and considerations for the radio's aerial and earth connections.
  • Concerns are raised about the potential for overloading the receiver with a large antenna and the implications of connecting to mains earth due to noise pollution.
  • A participant mentions the "Mini Whip" active antenna as a good option and shares a circuit diagram of the radio with relevant connections highlighted.
  • Impedance matching is discussed, with one participant stating it may not be necessary for the receiver in question, which typically has a high input impedance.
  • Safety concerns regarding the DAC90 receiver's live chassis are highlighted, with discussions on how to safely connect antenna cables.
  • A suggestion is made to explore publications from the RSGB for additional resources, particularly for UK-based participants.

Areas of Agreement / Disagreement

Participants express varying opinions on the necessity of impedance matching and the safety of connecting antennas to receivers with live chassis. There is no consensus on the best approach for connecting antennas to the DAC90 receiver, and practical safety measures are debated.

Contextual Notes

Participants mention specific challenges related to noise from IT equipment and the implications of using coaxial cables with different antenna types. There are unresolved questions regarding the input impedance of the setup and the feasibility of connecting a mini whip antenna to the DAC90.

Who May Find This Useful

Individuals interested in radio restoration, antenna design, and practical applications of antenna theory, particularly those working with valve radios and shortwave reception.

Guineafowl
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TL;DR
Recommendations for a book on design and theory of (receiving) antennas
I’ve recently restored a Cossor 501 valve (tube) radio, which can receive LW, MW and SW. It has an external antenna socket (for SW), and I’d like to gain some knowledge on how to design and build something to plug in to it.

A single wire about 20m long, draped out of the window, has enabled me to receive broadcasts in Spanish, Arabic, Mandarin, Russian (or similar), of varying signal strength, and I‘ve been experimenting with orientations and shapes. It would be nice to actually know what I’m doing.

So, I’m after a reasonably comprehensive book, possibly up to undergraduate level, on antenna theory. Suggestions, please.
 
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Since you are looking to home-brew your own antenna, this book is pretty much ideal for you:

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https://www.amazon.com/dp/0872599043/?tag=pfamazon01-20

If you have a local HAM Radio Outlet or similar store, they probably have copies for sale there, and can also give you some tips if you have questions. :smile:
 
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Thanks. It looks like that book will have to be shipped over from the US, but that’s ok. I’ll get my calculator ready for all those ‘orrible fractional inches :biggrin:
 
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A copy of that book ^^ is winging its way to me, all the way from California. Will take a week or two.

In the meantime, is there anything practical I can get started with? I was quite impressed with a simple long wire draped out of the window.

The radio antenna socket has ‘aerial’ and ‘earth‘ connections, and I’m seeking SW broadcasts, say 3-30 MHz. Standard valve (tube) superhet design. Transformer type, so isolated from mains.
 
There are a few subtleties with receivers like this. They often have ample gain, so large antenna is not necessarily helpful as it can cause overloading. Also the receiver has a ground, or earth, terminal which is unfortunately connected to the mains earth. This is undesirable due to noise voltages on the mains earth. We live in a very noise polluted environment due to IT equipment, so an antenna remote from the receiver with a balanced or coaxial feeder seems attractive. I have also had good reports of the "Mini Whip", which is a small, active antenna incorporating an amplifier.
 
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For interest, here is the circuit diagram of the radio. I’ve circled the relevant connections, which are made to L1, the internal frame aerial, in the absence of an external one:

image.jpg


Regarding a coax feeder, I’ve got some idea of impedance matching, but I don’t suppose there’s a hope of working out the input impedance of this setup?

I also have a ‘series set’ style receiver, a Bush DAC90A, which picks up a lot of SMPS noise. Would it be worth posting a schematic here, in case I can somehow connect in a mini whip, or perhaps start a separate thread?
 
Impedance matching does not matter in this case. These receivers tend to have an input impedance of say 500 Ohms, to suit a wire antenna. Just use a coaxial cable to connect to a remote antenna.
Be careful with the DAC90 as it has a live chassis.
 
tech99 said:
Be careful with the DAC90 as it has a live chassis.
Yikes! How can you connect antenna cables to such a beast?
 
berkeman said:
Yikes! How can you connect antenna cables to such a beast?
It has no aerial* connection, just an internal frame one for LW and MW only.

I’ve disconnected the 1950s swappable polarity power pins and fed in a permanent power cord to ensure the chassis is always to neutral (UK plugs are all polarised). As presented, there‘s no exposed metalwork, and presumably that was regarded as safe enough back then. Repair work (and scoping) is done while powered from an isolation transformer.

The UK regs require that any accessible ‘live’ conductors (to include both L and N) are double sleeved, so any feeder line/antenna* to a live chassis set should comply with this. I’m sure this could be achieved, even as an interesting theoretical exercise.

*Using ‘aerial’ and ‘antenna’ interchangeably
 
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If you are UK based then the RSGB have many publications at various levels.
this could be worth looking at.
 
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