momentum single port

i am using ads momentum to simulate a microstrip rectangular antenna,inset-feed operating freq 2.45GHz.i have put a port at the edge of the inset feed.i have tried 2 different port type(port editor) which is single and internal.simulation freq from 2-3GHz.i observed the following.
1) "Single Port" - plot of impedance Vs freq give almost a 45degree line, something like y=x line.the impedance varies as the width of inset-feed.
2)"internal Port" - plot of impedance Vz Freq show a horizontal line.impedance=50, irrespective how i change the width of inset-feed.

My question is which one i should follow to build my antenna and y the single port and internal port give such a result?

Hi,

I use the single port (default) to design my inset fed patch. It worked well.

Your observation for the single port sounds a bit strange.... why not just look at the S11? You'll see a sharp dip at the resonant frequency. Play around with the inset position, W and L to get what you want. It's possible to get S11<-30dB in simulation.


Rgds!

hi Gecky
i need to know the antenna impedance for my oscillator matching.anyway i am new in this field.am i in the correct track.pls guide me.

Hi Spide,

u see the photo beside my nick? that's my patch.. Ur design should have a similar shape if its a normal inset-fed retangular patch antenna.

U mentioned oscillator matching? I guess you are designing some sort of integrated RF rx or tx? Whatever the case, watch out for load pull since the patch antenna Q is rather high.


Rgds!

hi Gecky,yes i am design integrating oscillator working at 2.45GHz.as mention in my first case 1 observation,i dont understand y when i varied the length of inset feed,only the S11parameter will change but not the impedance of antenna.i am very confused coz as stated in a.Balanis book'(antenna) or any other publications that when i vary the length of inset feed the impedance should change accordingly.instead the impedance of the antenna remain constant unless i change the width of the inset feed line.or am i measuring the correct impedance at port1.i observed the impedance by plotting real(Z0) Vz freq. Hope u could clear up mind.thank you.