Array of Loops

[goldjackal]

I work on Radar systems in the military. One of our Radars uses a phased array of dipole antennas, which allows monopulse processing. Has anyone ever heard of any sort of project that involves an array of loop antennas? If so, do you have any information about how well it worked, pitfalls, etc? I'd like to have a rows of loop antennas to detect metals on a larger scale than is possible with a single loop, but like I said, I haven't heard of anyone using loop arrays, and thought maybe there was a reason for that.

Thanks,

- Jack

[Carl-NC]

In RF, there's no reason why you couldn't use loops instead of dipoles. I once built a Yagi-Uda using circular loops instead of dipoles, it worked fine.

But the coil on a traditional metal detector isn't an antenna, it's really a balanced transformer. The size of the coil is way too small (for the frequency being used) to employ phase steering techniques.

- Carl

[Altra]

Multi-loops

Jack,

Take a look at this patent. US 4912414

[goldjackal]

Carl, I didn't explain myself very well. I was planning on a single transmitting loop, with an array of smaller receiving loops. I don't really need beam steering, but want to take advantage of the benefits of a receiving array.

Mark, that patent is almost exactly what I was envisioning. Why do I always get beat to the patent office (by about 20 years at that)? heh

It's really interesting reading through their patent and viewing the images. It's pretty cool (viewing their included imaged) that they intended to put this on the back of a sub and run it through the water. I'd love to see that in action, and find out if they found anything cool. Thanks for sharing this. I can certainly apply it toward my own ideas and thoughts.

[Carl-NC]

What you describe was used in Vietnam-era mine detectors. The AN/PSS-11 had a single transmit loop, and 4 smaller receive loops. You can pick them up on eBay for $50-75 or so.

- Carl

[goldjackal]

Cool info. My eventual goal is to build a larger system than the AN/PSS-11, but I may purchase one of them to test with, and learn from.

Thanks for the info!

[sharky]

I work on Radar systems in the military. One of our Radars uses a phased array of dipole antennas, which allows monopulse processing. Has anyone ever heard of any sort of project that involves an array of loop antennas? If so, do you have any information about how well it worked, pitfalls, etc? I'd like to have a rows of loop antennas to detect metals on a larger scale than is possible with a single loop, but like I said, I haven't heard of anyone using loop arrays, and thought maybe there was a reason for that.

Thanks,

- Jack

Its there butu need a lot of DSP and good front end and timings at very speed