Transmitter and Receiver for GPR

[ali_cmi]

Hello,
I am a final year student of BEE Telecom. I chose my Final Year Project to design a Transmitter and Receiver for GPR. GPR has already been developed in my institute. It uses VNA (Vector Network Analyzer) as its source.

Some features of that project are:
-> Double-Ridged Horn Antenna
-> Synthetic Aperture Radar (SAR) with UWB source (VNA) in Mono-synthetic mode
-> Only s11 (first parameter of s-parameters) was measured by VNA
-> 2.4 GHz center frequency with 1 GHz Bandwidth---a pulse with 1 ns duration transmitted by a Stepped-freqeuncy transmitter
-> Tx and Rx are in VNA
-> Only Return Loss measurements are observed
-> Data from VNA is processed in Matlab to create a rough image of observed reflections

I hope the data above is enough for you to get the idea. I have just started working in the project

Since VNA is a multipurpose device and the already-implemented project used it to find S11 only, I chose this project to introduce portability in GPR. (VNA available in my institute is bulky)

In short, my goal is to develop a Tx and Rx which function as the VNA does; thus introducing portability.

The problem is that I have no idea where to begin. I need a head start. I need to develop complete understanding of how the Stepped-Frequency Transmitter (used in already-developed project) and compatible receiver works and I have to develop the whole system without changing other features like antenna, codes etc.

Please guide me and point me in the right direction.

Regards.
**broken link removed**

 

[biff44]

did you leave some details off? A commercially available VNA is not going to be happy trying to compute S11 on a 1 nS pulse.

If I were you, I would use something like an ADF4350 for the transmit/LO source. I would split the power, amplify with a lot of stages to get some isolation, then use a very high speed switch to generate a 1 nS pulse. Then I would use a diode sampler to catch the signal amplitude and phase info.

 

[ali_cmi]

@ biff44

No, Sir. The VNA does only that. Let me explain it a bit. It calculates s11, shows the real-time Return Loss curves as the GPR is moved over the test-bed and creates the file with magnitude and phase of Return Loss. This file is imported to Matlab and DSP is applied to it to get an image.

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Also sir, I am a BEE student. Just read a single subject on Microwave Engineering. I have experience of making single layered PCBs, working with PIC MCU and little bachelor stuff like that. Also, I made some EE projects.

I request you to share some data (papers, theses etc) which would give me a head-start on this project. As far as I know about the fast (1 ns fast) switch that you stated, its not cheap. Also, shed some light on the cost of this project. Most importantly, is it in my scope? I would give you any detail necessary.

Waiting anxiously for your response.

Thanks.

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Sir, I request you to please keep this post alive.