Antenna

[houman-1992]

Hi dear Margarita,
I am Houman from Sharif University of Technology, recently I got interested in building your project GPR TU1208, and maybe developing it a little bit. but there are some questions left in my mind about the antenna. I want to know your opinion before buying the components. I would be appreciated if you could help me out.

1. and I use other type of antenna instead of LPDA? you used an LPDA antenna with 6 DBi gain, what if I use "UWB Directional High Gain antenna" like this one (https://www.gearbest.com/other-accessories/pp_009809317913.html) or this one (https://www.amazon.com/Ultra-Wideband-High-Gain-Directional-Antenna-700/dp/B07XSP2CFM) with a gain of 9 DBi, will it work?
2. I'm going to replace RF components with their SMD equivalent and design a PCB for this part, can I connect antennas directly to the PCB or it should be a little far from the PCB?
3. and finally, how long is the distance between Rx and Tx antenna? is the distance important at all?
   thanks in advance for your help

[Ritchizh]

Dear @houman-1992
Thank you for your interest in this project.
Unfortunately, I cannot help you much: the project has ended in 2017 and only a prototype was produced. I provided all the files I have "as it is".

1. You should use another type of antenna depending on your application. For example, check this article: https://www.scielo.br/scielo.php?script=sci_arttext&pid=S2179-10742018000300385&lng=en&nrm=iso&tlng=en
2. You can connect antennas directly to the PCB using the appropriate feeders, however RF design rules should be considered - like impedance match, decoupling between power and ground etc.
3. The distance is important because: 1) it defines your radar type - is it monostatic, bistatic, MIMO - you get different resolution and do different signal processing. 2) there's always direct signal from Tx to Rx that should be reduced, since it masks the weaker reflection from the target and decreases dynamic range of the Rx.
4. Kindly also check these links:
   https://github.com/search?q=fmcw -- there are some similar radar projects that include signal processing software.
   https://github.com/kopytjuk/python-fmcw/blob/master/RADAR.ipynb -- I find this tutorial helpful.

[houman-1992]

Thanks a lot for responding. That was a whole host of help.
There is another question if you don't mind. How deep can it penetrate in normal soil?
Thank you