Microstrip patch antenna

[Mightyx]

Hi everyone,

I'm trying to design a microstrip patch antenna but when i simulate on Ansoft Designer i don't find good results.

First, i find W with W=(c/2fr)*sqrt(2/\[\epsilon\]r+1)
then i find L with L=c/(2fr*sqrt(\[\epsilon\]eff)) - 2\[\Delta\]L
and then i don't find the input impedance. When i search into internet i find different calculs:
1) Zin= (90*\[\epsilon\]r^2*(L/W)^2/(\[\epsilon\]r-1)
2) Zin = \[\frac{1 }{ Yin}\] with Yin= 2G with G=\[\frac{W }{120\lambda\]o*(1-\[\frac{{(ko*h)}^{2 }}{24\])

What's the good answer ?

I have a second question: is it possible to create microstrip line antenna ? It's mean not a rectangular antenna but line antenna ?

Thanks a lot!

PS: Sorry for the equations...

 

[Migueltron]

Hello Colleague,

- I found an accurate equation for Zc in the book "Antennas for all applications" by John D. Kraus:

Zc= Zo/(√ε r[(W⁄t)+2)



Where:
Zc= Characteristic Impedance
Zo = Intrinsic impedance = 377Ω
ε r = Dielectric constant from your material: I guess is FR4.
W = width of you patch, normally minor to the wavelength
t = thickness from your board

- Answering your second question:
Yes it is possible to have one trace antenna as mono pole or dipole, also it could be a loop antenna. Ig you open a keyfob you will find some of these antenna inside to transmit the signal to lock/unlock a car.

Regards,
Migueltron

 

[Mightyx]

Thanks you Miguel!

But I'm trying to search the input impedance of the antenna, not the characteristic impedance. I believe that's different.