monopole simulation at 10GHz in hfss v9.0
I am trying to simulate a lamda/4 monopole at 10GHz in hfss(version 9.0).I use a lumped port excitation(small rectangle) between the monopole and the infinite ground plane.The main problem is that the radiation pattern is not omnidirectional for 0<phi<360 deg at a constant theta.There are major and minor lobes.I have tried many simulations and increased significantly the number of tetrahedra for the simulation but have found no difference.The monopole is very thin and i have used both cylinder and polyhedron to simulate it.Can anynone give me some advice?
Thank you all in advance.
What is S11 of the antenna? Is it matched at the frequency you expect?
Thank you very much for your help!.
Well the monopole was not very well matched so i varied the monopole length using a parametric analysis.At 0,23*lamda s11 is about -30 dB.The radiation pattern is better but still not ok.If i achieve s11 less than -60 dB would it be almost like a circle for a constant theta?Is there some other parameter i should consider?I really cannot understand why such a symmetrical model is not omnidirectional for 0<phi<360 for a constant theta.
Hi !
m.b. usage of the lumped port is wrong . if this port is not small enough u may obtain result whitch not been expected.
please look at this example of MW Studio, mb this will be helpful in your case too. MWS guys use waveguid excitation and two simmetry planes and all is OK.
http://www.jedi.net/%7Ejustin/CST/monopole.html
Just solve your's problem by IE3D with monopole 7 mm lenghs and 1mm diameter, lumped port is connected at 0.05 mm above grounding plane. Mesh by 1/32 lambda.
I have no any problem , right circle and S11 -24 dB at 10.2 GHz.
Try to change excitation and forget about S11 - not this is your problem.