microstrip patch antenna with HFSS

[parisa]

how can i better s parameter of my antenna?
my s parameter is high around -1 , -0.6 , .....

 

[eraste]

Hi,

See the matching technic...
Your feeder is perhaps not matched to the antenna.
If it is a square patch move your feed along the symetry axis of the square. At the center the impedance is near a null at the edge the impedance is rather maximum (a few hundred of ohms). The variation follows a cosinus square : Z = Zmax cos²(Pi x/ L) ; x=0 (the edge) Z=Zmax and real at x= L/2 Z=0. Between the two extreme value you will find the match impedance.

Bye.

- - - Updated - - -

Hi,

See the matching technic...
Your feeder is perhaps not matched to the antenna.
If it is a square patch move your feed along the symetry axis of the square. At the center the impedance is near a null at the edge the impedance is rather maximum (a few hundred of ohms). The variation follows a cosinus square : Z = Zmax cos²(Pi x/ L) ; x=0 (the edge) Z=Zmax and real at x= L/2 Z=0. Between the two extreme value you will find the match impedance.

Bye.

 

[Nhera]

L is inversely proportional with frequency.
W is SLIGHTLY inversely proportional with frequency and impedance of the patch
y0 is inversely proportional with impedance of the patch
wf is inversely proportional with impedance of the line

First start off by some reasonable values. There are formulas online.
Then make sure wf is 50 ohms.
Then adjust L so that the smallest reflection is at the frequency of operation.
Then adjust y0 so that the input impedance is 50 ohms.
During this process, try to keep W:L ratio to be around 4:3 or 5:3