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Problem of Grass-Clutter in Radar calibration ..

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Member level 2
Jun 17, 2002
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grass clutter

Sorry if this is posted to the wrong place ....
(Have browsed the whole forum .. and don't known where to post this) ...
This must be the place ......

I have a problem in calibration of a radar system.
The model for calibrating a radar system without Grass-clutter is

M = R*S*T
M = measured matrix
R = receive distortion matrix
S = scattering matrix of calibrator
T = transmit distortion matrix,
All the matrices are (2 by 2 ) ...

With this definition ...only 2 calibrators ...
are enough for determining the R & T distorsion matrices.
(and hence the radar system is calibrated)

The model above is often used in literature ...
However, IMHO this is not correct ..
Because when the calibrator is positioned on a Grass-field,
the effect of the Grass-clutter must be taken into account.

If the Grass-scattered field is Additive then the model
must be; case A:
M=R*S*T + C ; where C= scatterding matric of Grass-Clutter

If the Grass-scattered field is Multiplicative then the model
must be ; case B:

The case B is never mentioned in literature ...(IMHO)
I wonder if anyone can give me a hint on how to calibrate this case ...

Is the Grass-clutter additive or multiplicative quantity ? ...
I think it is multiplicative ... what is your ?

Antenna & Radar Guru's ... please jump in, tell your idea and,
have a discussion together ...


i depends what you want too get as a final result from the actual grass

if you calibrate as addative then this image will be subtracted from the screen

if you calibrate as multiplicative then you are adding in the image of the grass as an image

also it depends what type of radar and what freq

grass will only respond to certain freq {as does anything}

too give a very noticable effect

there for too subtract from radar screen you additivly calibrate {ie adding in the grass too the zone your scanning too eliminate it

if indead your talking of a fixed scaning {rotating} radar pod

Hi !!! MONKEY!!! ...:) ..:) ..........

Thanks for Your prompt reply..
It's short and very comprehensive ...:) hehe ....

Some thing not very clear to me is :
1) There must be a certain correlation between the calibrator and Grass ...

When the folowing paths:

radar-grass-calibrator-radar = CS
radar-calibrator-grass-radar= SC
radar-grass-radar = C
radar -calibrator-radar = S

are taken into account,

then the additive model is not correct ..(IMHO)
and is must be modified to,

M=R*(S+C+ CS +ST)*T ... (tell me if I'm wrong here)


2)I want to calibrate out the Grass-Clutter ...
what model do I have to use
M= R*S*T +C,
M=R*(S+C)*T, or,
M=R*(S+C+ CS +ST)*T,

3) What is the procedure that I can use to calibrate a
10GHz-FMCW -Polarimetric radar then ?? ..I'm confused ...

anyone ? any idea ???
any reference ?? any literrature ???


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