Radar antenna (24GHz, 77GHz or 79GHz)
I'm looking to put together a simple radar system.
I've been looking at the Infineon BGT24MTR11 evaluation board, (sense2go) but am thinking of getting the more expensive BGT24-RFB2412. There are issues around 24GHz, (temporary band, astronomy stations, etc.), so we may actually move to 77GHz or 79GHz.
The radar system must be capable of detecting object from a distance of 100m, (BGT24 has this capability) and a 20 degree field of view should be sufficient
I assume we will need a high gain horn antenna, however I been unable to find any for purchase, (L-Com/ Pasternack/ DigiKey).
Does anyone know where such an antenna could be purchased?
You can google "horn antenna" to see many manufacturers. I can recommend "www.cernex.com". Make sure you also order a matching coax/waveguide transition. Good ones cost as much as the horn. You can also use scissors and a soldering iron to make your horns of tinned steel sheet or thin copper or brass sheet. I made my horns for 5 USD apiece, with good results.
BTW, a horn antenna with 20-degree radiation pattern will have 16 dB gain approx. if designed with equal E/H patterns.
A costly standard-gain horn with 23 dB typical gain will cost you close to 400 USD from a commercial source.
BTW, a horn antenna with 20-degree radiation pattern will have 16 dB gain approx. if designed with equal E/H patterns.
A costly standard-gain horn with 23 dB typical gain will cost you close to 400 USD from a commercial source.
Thanks jiripolivk,
One thing I neglected to mentioned is that the position from the orthogonal is required, (distance and angle).
I've started looking at phase arrays: http://www.radartutorial.eu/06.anten...ntenna.en.html
Still unsure how best to proceed... Do you have any links that describe how to build a frequency specific horn antenna? Will a horn allow discovery of position as well as distance?
Thanks,
Seán
Only if you mechanically sweep a much narrower horn (Or electrically long slot radiator), or use LOTS of them to do a phased array, you might be better with an array of patches or bow ties working over a ground plane.
You might I suppose be able to do some kind of bearing measurement based on interferometry if you can modulate the transmit signal in a suitable way with only two rx channels (or one plus some pin diode switches and two aerials), but that gets really messy.
By 24GHz you are getting well into the space where things like PCB material starts to really matter, and feedline losses even over short distances become a real problem.
Plenty of stuff on DIY horns as well as the other obvious variants in the ham radio literature, "VHF/UHF Handbook", "Dubus" all that sot of thing.
I don't think this is a space that has obvious off the shelf dev kits, you need a microwave systems grey beard to design this stuff for you (That part you are looking at is aimed at motion detectors, simple Doppler speed measurement things and stuff of that nature, not really imaging radars).
Regards, Dan.
Yes would be great to get a grey beard to do this for me!
I've a fair bit of experience around 10GHZ and at the first harmonic just over 20GHz and implemented code to look at the doppler at 20GHz and use it to calculate velocity. However, when it com,es to antenna design my beard is distinctly no grey.
Skin depth, Maxwell's equations,etc. are all important at 24GHz but I really don't want to go down that rabbit hole, I'd rather just buy a decent radar antenna/ unit off the shelf. Looks like that's not economically possible, i.e. we're looking to prototype and then build a thousand, paying S400 per antenna is not a runner in such a situation.
Any ideas how we could get a decent antenna for around S40? We could pay around for all design costs, (assume this would be around S10 - S20k).
From your questions that look to me quite naive I would recommend you to study radar systems and antennas before spending money on unknown stuff. You can google my paper "An Overview of Microwave Sensor Techology by J.Polivka" with minor details, in HFE magazine 2010 I think.
Any radar system can be designed to detect target position and distance. Finer position detection requires either a larger antenna aperture or using an interferometer (antenna matrix).
I have commented on horn antennas. So far you had no idea on how to specify one, so read books to get it. Then try to make your horns for experiments before you decide what to purchase.
J.Polivka,
I agree, I'm very rusty, it's nearly five years since I last used a horn antenna and 15 since I designed an antenna.
I was hoping I could get something that worked but as you suggest maybe it's better to spend some time studying.
In summary,
- try cernex for off the shelf solutions
- horn will do the job
- Read http://highfreqelec.summittechmedia....07_Polivka.pdf
I've a couple of weeks off over Christmas, so time to start swotting and may come back here again in the New Year.
Thanks for your help,
S