question about Archimedean spiral antenna

[caocao]

Hi everyone,
There is a question in Archimedean spiral antenna.I want to enhance gain of the antenna,a cavity was added on the back of the spiral and about 1/4 labuta from it.I had simulated the antenna in hfss and found that the axial ratio of the antenna increased too(from 1 dB to 7dB).I consulted lots of papers about it ,but they didn't mention the phenomena.
How to solve this question?
Thanks and regards!
caocao

 

[s.mollaee]

Hi
I have such a problem with my spiral!
your Thread was for a long time ago.I think you had already solved the problem.
if you had solved it please help me.
how can I decrease The Axial ratio in Spiral antennas and ehat are the parameters here?
Thank you

 

[ferdows]

whit abs you can reduce the axial ratio

 

[s.mollaee]

what do you mean by "with abs ..."?
my question is "what are the important parameters on axial ratio of a spiral antenna".
regards

 

[ferdows]

see this paper
send your file to my email: ferdows_j@yahoo.com