Assigning port excitation to PIFA

[Shashiketan]

I have made an PIFA antenna with ground plane, substrate and patch. i have shorted the patch the ground plane and attached a feedline to it. i am confused now how to assign port excitation. whether it should be lumped or wave? how to ensure the area of excitation.

please help..

 

[WimRFP]

Generally spoken wave excitation gives most accurate results. However if you don't have room/space for the additional segments that are used by the de-embedding, you can use a lumped port. For an antenna where VSWR requirements are not that high (for example VSWR<2), the inaccuracy is accaptable in most cases.

If you use a lumped port, change the size (length and width or heigth and width) to check whether the changes in impedance are accaptable. length is size in direction of feed current

Make the width of the port equal to the trace width, and use length=width as a first guess, and make sure the size of port <<< wavelength. Small length/width ratio gives capacitive effect and large length/width ratio gives dominant inductive effect.