UWB antenna by using HFSSS

[candemir]

Hi all,
I`m trying to simulate an UWB antenna from an IEEE article; but I have some problems with Excitations (waveport or lumped port and their dimension) and Radiation boundary. the result off simulation is not the same as posted in the article.
I have attached hfss file,

Maybe anyone has some suggestion to solve my problem.

thanks and best regards

candemir

 

[Ivan_]

Candemir,
if I were u, first of all I would try to remove the coax feed. As u can see, the pin is not correctly connected to the structure. It touches both the signal and the ground of the microstrip. It cannot be working. So, reduce the airbox size in order to place a conventional HFSS rectangular wave port. Airbox must be separated by a λ/4 distance at f0 on each side of the structure (apart from the one with the wave port which must touch the metal trace of the microstrip). Another problem is the placement of the radiating element: u placed it at the border of the dielectric. Of course border diffraction effects affect the antenna input impedance. What I suggest is to make the dielectric wider and place the radiating element at the center of it. Make sure that the distance between the antenna border and the dielectric border is sufficently large (i.e. 1 or 2λ) in order to let border effects vanish and not affect antenna input impedance.

I.

 

[candemir]

Thank you for your advice.
I am gonna try them,if i obtain new resutls,i will inform you,

best regards
candemir

Added after 1 hours 46 minutes:

Hi,Ivan
In addition to i am attaching to original shape of microstrip,

Maybe you can have idea to use waveport and lumped port. Because i realized that desinger had used a coax_pin.

i`m already appreciated for your help

best regards

candemir

 

[Ivan_]

Of course u can use the coax excitation, but it must be correctly set. Coax pin has to be lying and touching only the signal trace. If u make it touching both the signal and the ground, the structure cannot be working because in that case u would have signal and ground at the same potential. I think waveport are good enough for simulation purposes. Just make the microstrip to touch the airbox face where u want to put the port. Then draw a rectangle with the following characteristics:

°Height: 4/5 times the substrate height (starting from the ground plane);
°Width: 3/4 times strip width should be good enough.

These dimensions represent just the rule of thumb but they can be changed based on the structure geometry. Usually, I use a more complicated method to choose port dimensions, but I think the standard rule should be good for ur purpose.

I.