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I am interested in RADARs. However, I don't have enough time to go to school for studying RADARs. Therefore, I am thinking about self-study.

What kind of low-cost equipment do I need to learn and experiment with RADAR technology at my home?

user366312
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    What do you want to learn? Where are you located? Radar used radio waves (hence the name: RAdio Detection And Ranging). Radio wave transmissions are legistated to stop you jamming your TV, radio, air traffic communications, mobile phones, GPS, etc etc. So what you're allowed to do legally varies around the world. – Puffafish Jun 27 '22 at 10:27
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    Choose an area of spectrum you're allowed to use, and get a couple of cheap antennae suitable for that. Buy a SDR (Software Defined Radio) to use with your PC, making sure it covers that frequency range. – Neil_UK Jun 27 '22 at 10:27
  • what sort of budget is involved? Is the intention to use the radar to track the local cat to mmm precision, or maybe something more useful? Point being is you need to be a lot more specific about the radar specs as AESA radar doesn't tell us much. – Kartman Jun 27 '22 at 12:13
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    As it's an AESA, buy N SDRs, where N is >1 and <budget – Neil_UK Jun 27 '22 at 12:56
  • You know the radar equation? The necessary radar transmitter power is proportional to the fourth power of the distance. So low cost equipment may work only over a short distance only. – Uwe Jun 29 '22 at 02:40

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Doppler RADAR works by transmitting a signal and mixing reflected energy from the target with the local oscillator. Target velocity produces a shift in frequency of the reflected signal and the mixer provides the difference frequency to allow target velocity to be determined. A simple Doppler RADAR system can also be adapted to provide distance ranging RADAR with "some work".

You can experiment with Doppler RADAR with units available for a few dollars.

Here is an excellent writeup of the low cost LV002 / RCWL-0516 units with circuit diagrams, operation analysis and timing diagrams. This can be used to both understand the operation units in detail and to look at what is involved in producing your own.

This level of detail is rarely available for mass produced low cost units.

As a bonus, they link to this patent which discusses operation in detail.

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This web search provides links to a large number of sources.

Some come with metal screens which MAY offer somewhat better stability - but unscreened units may allow easier 'playing'.

Examples onlY - here & here &

DISTANCE MEASUREMENT

Distance measurement by RADAR usually involves the measurement of time of flight of a transmitted and reflected signal. Modern equipment often measures the time taken directly. This can be challenging for small distances and DIY equipment.

A surprisingly good introduction to a simple means of producing distance ranging RADAR can be obtained by studying the WW2 APN1 Radio Altimeter.
This avoided the complexity of directly measuring "time of flight" by saw tooth modulating the transmitter fequency so that when the reflected signal returned the transmitter was on a different frequency and the difference signal frequency corresponded to the time that the saw tooth modulated tx oscillator had had to change frequency.

This circuit at first (and maybe second) glance may seem arcane, but, by visualisng the top left 2 valves as diodes and the bottom left 3 valves as transistors the complete core operation may be understood. V101 and V102 (top left) are a diode balanced mixer that mixes TX & RX sgnals and produces an output signal corresponding to distance to target (ground in this case).
V112 and V113 (bottom left) form a push pull transmit ocscillator. The adjacent Af oscillator (V111?) performs the magic - it's signal drives an electrically variable capacitor in the tank circuit of the TX oscillator an sweeps its frequency. In modern equipment this could be achieved with a varactor diode.

A web search for "APN1 RADAR" with produce much more information.

Web references:

There are many websites describing how you can make your own RADAR of various sorts.
Some provide substantial expalanation.

Web search "DIY RADAR" here

Web search - videos here

Image search - this is especially useful as the images often give an idea of complexity and approach and each is linked to a website here

Free MIT syntheticaperture RADAR course here

Actual RADAR unit costs about $US350 to build but is more "real" than many.

Much related - earch for "coffee can RADAR"

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Russell McMahon
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