Prototyping an antenna array receiver

[an_avid_brat]

(cross-posted at Electronics StackExchange)

Disclaimer: I am decent with math/theory, but I have zero hardware knowledge (apart from some basic microcontrollers).

I'm looking to build a (possibly crude, but functional) hardware prototype of a receiver with an antenna array. The application involves frequencies in the 2.4 GHz ISM band. I am experimenting with array processing algorithms and would like to be able to play around with the array geometry a bit. I would also like to do most of the processing in software. Given my background though, I have very little clue how to start. In particular, I've been trying to read data sheets for various types of components, but I can't figure out what the components expect as input and what they output.

Here's what I've figured out so far:

I'll need a couple of antennas, of course, close enough so that I don't get spatial aliasing. The antennas will need to be connected to an RF front end, which does the downconversion. At some point, I'll need an ADC for sampling, and then I'll need a 'bridge' into software.

Assuming what I just described at least makes a little sense, here are my questions:

1. How do I bridge the RF front end and the ADC?
2. How do I bridge the ADC and the software part?
3. Can I make things a bit simpler?, e.g. can I try oversampling the received antenna signals and then just doing everything in software from there?

Additionally, is there a decent resource for learning about practical RF circuitry and prototyping? I think that is perhaps where I am weakest and need the most help.

Thanks!

 

[Dan Mills]

Have a look at something like the Ettus research USRP, which will do all the tricky stuff for you.

As far as books on RF prototyping go, "Experimental methods in RF design" is possibly worthwhile, but the microwave bands are tricky, tricky things, and you might do better starting off with experiments in the VHF or below where everything is easier.

73, Dan.

 

[an_avid_brat]

Dan,

Thanks for the advice. I did take a look at the USRPs, and specifically, this page:

http://decibel.ni.com/content/docs/DOC-25716

The cost and volume gets a bit prohibitive, though, since I would need a single USRP for each antenna in the array. Is there any way I can multiplex (in an analog sense) the antenna signals?

Thank you for the book recommendation - I will check it out.

 

[Dan Mills]

You could iff the transmitter was a single tone, but it sounds like a pain (A mess of pin diodes in all probability), I however was thinking more of something like the ettus B210 which will handle 2 syncronous rx directly, and is a nice single board solution.

There is not usually enough money in the world to make NI gear a reasonable approach.

I have been playing with locking a load of those cheap TV dongles to a common clock and using them to do beamforming, but that is a somewhat lower frequency thing (I wanted to play with using DAB radio multiplexes to do radar).

73, Dan.

 

[an_avid_brat]

Right - I think I've decided to go with the Ettus USRP (or similar) approach. I've noticed that the cheaper dongles are only available for lower frequencies, which makes me think designing my own 2.4 GHz receiver would take up quite a bit more time than I have.

Thank you very much for the help!