#### Terminator3

##### Advanced Member level 3

I hope somebody can share experience on patch impedance formula gives correct result.

This calculator gives me 234 Ohm impedance:

http://www.emtalk.com/mpacalc.php

and it seems that it uses formula similar to Zin= 90*(Er^2)/(Er-1) * (L/W)^2

or to G=W/(120*lambda0)*(1-1/24*(k0*H)^2), Zin=1/(2*G), k0=2*Pi/lambda0

This calculator gives 467 Ohm impedance:

http://www-antenna.ee.titech.ac.jp/~hira/hobby/edu/em/antenna/patch/rect/index.html

and uses formula Zi=0.5*Rr=0.5*90*(lambda0/W)^2

as w<0.35lambda0

(or w<lambda0 according to patch antenna primer by J P Silver):

G=1/90*(W/lambda0)^2

Zin=1/(2*G)

and can give the result similar to emtalk only for W>2lambda0 formula

also author of second page states something about impedance is twice or half in his experience.

Also it is unclear how to obtain patch impedance from Sonnet lite. It is possible using S11 value. but we must put some feeding line to add port. I also moved reference plane to patch, but impedance based on S11 value gives less than 100 ohm zin, which is unrealistic. Incorrect setup with autognd port on patch gives Zin around 200 ohms, but from formulas above it must be more like 400 Ohms. Please explain me in which direction shoul i move to clarify imput impedance approx. value.

This calculator gives me 234 Ohm impedance:

http://www.emtalk.com/mpacalc.php

and it seems that it uses formula similar to Zin= 90*(Er^2)/(Er-1) * (L/W)^2

or to G=W/(120*lambda0)*(1-1/24*(k0*H)^2), Zin=1/(2*G), k0=2*Pi/lambda0

This calculator gives 467 Ohm impedance:

http://www-antenna.ee.titech.ac.jp/~hira/hobby/edu/em/antenna/patch/rect/index.html

and uses formula Zi=0.5*Rr=0.5*90*(lambda0/W)^2

as w<0.35lambda0

(or w<lambda0 according to patch antenna primer by J P Silver):

G=1/90*(W/lambda0)^2

Zin=1/(2*G)

and can give the result similar to emtalk only for W>2lambda0 formula

also author of second page states something about impedance is twice or half in his experience.

Also it is unclear how to obtain patch impedance from Sonnet lite. It is possible using S11 value. but we must put some feeding line to add port. I also moved reference plane to patch, but impedance based on S11 value gives less than 100 ohm zin, which is unrealistic. Incorrect setup with autognd port on patch gives Zin around 200 ohms, but from formulas above it must be more like 400 Ohms. Please explain me in which direction shoul i move to clarify imput impedance approx. value.

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