antenna-theory.com

[settpjay]

hi , i just read the antenna theory about slot antenna just
and i had some questions.
accroding to the text book, slot antenna and dipole antenna
are complementary.

if there is infinite metal sheet on the XZ plane and slot is located at Z axis, then the omni-direction will be in XY plane and null show in yz plane.

but these result are based on slot in infinite ground plane.
so if the ground is finite plane, what would the 2D pattern become
in each plane.

and then i did a simple simulation in HFSS using HFSS design kit to build the model.
the target freq is 0.95GHz and metel sheet is on XY plane,
slot located on Y axis


the S11 and smith chart is good


so I simulatate the 2D pattern for slot antenna for single freq point at 0.95GHz
but I found something wrong in my 2D pattern


accroding to the theory in textbook, the Omni-direction pattern should appear at XZ plane, null at YZ plane in my simulation.
but my simulation result show that Omni-direction pattern should appear at YZ plane, null at XZ plane in my simulation.
It is totally different from the theory. what happen to my simulation? thank you

[helix]

I think some of your trouble has to do with the coordinate system you're calculating far fields in. It's easiest if you define a new coordinate system for the far field calculation whose z axis is aligned with the slot. If you post those results it will be easier to tell if you are having another possible problem.