Looking for recommendations for a good Antenna book

[Guineafowl]

TL;DR Summary

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.

 

[berkeman]

Since you are looking to home-brew your own antenna, this book is pretty much ideal for you:

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.

 

[Guineafowl]

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

 

[Guineafowl]

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.

 

[tech99]

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.

 

[Guineafowl]

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:

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?

 

[tech99]

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.

 

[berkeman]

Be careful with the DAC90 as it has a live chassis.

Yikes! How can you connect antenna cables to such a beast?

 

[Guineafowl]

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

 

[sophiecentaur]

If you are UK based then the RSGB have many publications at various levels.
this could be worth looking at.