IE3D vertical feeding problem

i've run several models (both monopole and dipole) using the vertical port definition and have gotten some impedance results that i just cant believe. what kind of considerations must i entertain when using the vertical port? i attached a typical model which has a vertical port defined from 100 mils to 0 mils with infinite GP at 0 mils.

also i cannot use the same port definition when using a finite gp versus an infinite. for example with the model i attached i have a small wire defined from gp (0 mils) to 100 mils which i defined as vertical port. however if using a finite gp IE3d forces me to define a small wire from 100 mils to 50 mils then 50 mils to 0 mils and then define the port from 100 mils to 50 mils.

I am looking for a very wideband response also.

if you have any advice thanks.

ghb

Hi:

I checked your structure. It is not v-localized port's problem. Basically, there are two problems in your model:
(1) The two crossing polygons are constructed as two pieces of flat polygons. They cross each other. However, in IE3D, they are not connected. You need to build it as 4 pieces with each piece as a quarter. Certainly, you can divide them along the center line of the current model for it.
(2) The 4 polygons are not connected to the circular like section close to the feed. They are connected by one vertex only. On IE3D, we need them to be connected on edges.
Furthermore, the AEC setting is not correct. It is too small. Whe it is too small, it is possible it may cause accuracy problem.