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# Calcul feed point position on patch antenna ?

## Calcul feed point position on patch antenna ?

(OP)
Hi all,

I would like to find some papers explaining how simply determine (calculate)the feed point on a rectangular patch to get natching with a 50 Ohm coaxial.

I don't have any analyser to perform measurement...

I just have a formula giving the variation of input impedance as a function of feed point position:

R(x)=R0 cos²(Pi.x/L) Where R0 is the résistance at the edge of the patch and x the distance from the edge. L is the dimension of the patch.

How can I determine an approximative value for R0, x ?

I took this formula from the article "Design of rectangular Patch antennas for the 2.4 Ghz band" - Dr. Max Ammann  from
Applied Microwave & Wireless.

### RE: Calcul feed point position on patch antenna ?

(OP)
ok, I found some answer in "Microstrip Antenna Design Handbook" I.Bahl P.267,287

x=L/2ãƒÃre(L) where

ƒÃre(L)= (ƒÃr+1)/2 + (ƒÃr-1)/2F(L/h) and
F(L/h)=  ã(1+12h/L)

Maybee it can be usefull for someone else...
Toulouse.

### RE: Calcul feed point position on patch antenna ?

Suggestion: Visit
http://www.swissatv.ch/documents/Design_Rectangular_Microstrip_Patch_Antenna.pdf
and check Reference [8]:
8. Carver, K. F., and Mink, J., “Microstrip Antenna
Technology,” IEEE Trans. Antennas and Prop., AP-29,
1981, pp 25-37.
for:
R0 is the resistance at the edge of the patch and x
is the distance from the edge.

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