Electronics > RF, Microwave, Ham Radio

Hobby radar design

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sckzor:
Hello forum,

I am a software guy, recently I have become interested in writing software that relies on data that can only be supplied by a radar system.  The issue is that every off the shelf radar I have seen has been very expensive and not really what I am looking for.  I want a dead simple analog radar that I can aggregate data from without much work.  When looking for something like this I found a project made by MIT (here https://ocw.mit.edu/courses/res-ll-003-build-a-small-radar-system-capable-of-sensing-range-doppler-and-synthetic-aperture-radar-imaging-january-iap-2011/pages/projects/) that is basically exactly what I was looking for.  The issue with theirs is that it is rather large, clunky and still more expensive than I would like.   For this reason I took the schematics made by MIT and created what (I hope) is a schematic for a similarly spec-ed one made from cheaper surface mount electronics. I have done some simple projects with analog electronics and a little bit of RF stuff but I have never made a project as complex and RF intensive as this before.  Before I dump a large chunk of change on the parts for this board though I would like to get some input on whether or not it will work as I intend.  I have placed a link to a picture of the schematic for the project as well as the five different uncommon ICs that I put in it.   All other parts should be generic or common parts like 555 timers and op-amps.

If anyone has time to check this I would really appreciate a fresh, more experienced set of eyes looking at it.

Many thanks,

sckzor

Link to schematic: https://files.sckz.org/uploads/1660268499506579982.png


Raltron RQRA-2328-2536-CR VCO: https://www.raltron.com/webproducts/specs/VCO/RQRA-2328-2536-CR.pdf
KYOCERA AVX AT 0603 Attenuator (3db): https://datasheets.kyocera-avx.com/AVX-AT-Series.pdf
NXP BGU8052: https://www.nxp.com/docs/en/data-sheet/BGU8052.pdf
Analog Devices HMC213BMS8E: https://www.analog.com/media/en/technical-documentation/data-sheets/hmc213b.pdf
AEROSEMI 2A Step Up Converter: https://www.olimex.com/Products/Breadboarding/BB-PWR-3608/resources/MT3608.pdf

radar_macgyver:

* You have the RF and IF ports on U5 flipped.
* I'm assuming AE2 is the receive antenna, in which case U4 is backwards (you have its output connected to the antenna).
* Connect all the NC pads of the VCO to ground.
* Get some good antennas to go with this. L-com is one place to look for 2.4 GHz wifi gear.
* The LM324s will run on +5V, so ditch the SMPS. You could also consider a proper R-R opamp (LM324 only goes down to ground).Otherwise, it looks like a decent design, looking forward to seeing your results :)

Berni:
Do watch out how you do PCB layout for the RF parts as parasitic effects and transmission lines are very important for RF. It can make the difference between this turning into an unstable noise machine or a well performing radar.

This is likely the reason that the MIT students went with ready made RF blocks. You don't need to know anythyng about RF design to just plug them together and have them perform to what the datasheet claims (they are just SMD chips in a metal box with connectors anyway). But yes these RF modules can be pretty pricey. Most of the time they are used for prototyping things or in niche small volume RF equipment.

If you just want a radar to play with these are some ready made radar modules that implement just the RF stuff on a board (LO, Mixers, Amplifiers, Directional patch antenna..etc) and operate in the frequency bands designated for radar like 10Ghz and 24Ghz. What you get out of them is the ready to go IF out of the mixer.
Example of one: https://www.aliexpress.com/item/4001178786384.html?spm=a2g0o.productlist.0.0.7f052399TPu4Cy&algo_pvid=25a6a566-3d13-43e7-8a85-414307386cd7&algo_exp_id=25a6a566-3d13-43e7-8a85-414307386cd7-8&pdp_ext_f=%7B%22sku_id%22%3A%2210000015056303221%22%7D&pdp_npi=2%40dis%21USD%2134.16%2131.77%21%21%2111.62%21%21%40210318cf16602820166238419eaf5c%2110000015056303221%21sea&curPageLogUid=FRkCv64z6iAM

tggzzz:
Make sure you are legally allowed to transmit the radio signals, and that you won't "inconvenience" other users in the band or in other bands.

Authorities tend to become ratty and punitive if they have to discover why people are complaining.

geggi1:
I have seen presentations where cheep SDR hardware are used as radar on 2,4Ghz.
Some radardesigns are passive radar type based on WIFI ewuipment.

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