spiral antenna feed by microstripline: Urgent

[kaandee]

hi friends

I'm new to CST MWS. I have designed single arm spiral antenna and feed by microstrip line as shown below. I got the frequency VS S parameter graph is not a proper one. I don't know why it is. I want to get frequency VS radiation graph and frequency VS returnloss graph. How can I get it using CST. plz can any one help me ?....
Any one suggest me...how can use microstripline feeding to spiral antenna. Is it correct which i have used below.

I have used transmission line calculator to find the parameters for substrate and microstrip line

 

[e_m_c]

Attach your model - it will be easier to check what is the problem

 

[kaandee]

hi i have attached my model here.....I'm using CST MWS 2008. I want to get radiation patterns...i don't know how to do it...plz help me....i have a problem with microstrip line feeding....bcoz frequency VS S parameter graph is not proper one...
plz help me...how can i get proper one....

Thank you

 

[prafuldeo]

hello kaandee,

from s11 we can see that your antenna is not radiating. The normal way to feed an spiral antenna is to center feed by coaxial probe from bottom. The way you are feeding is unusual for spiral antennas. Have you simulated a paper or this you done by yourself? try to bottom feed in centre and then compare the results. Also upload the paper with which you are comparing the results.

Best of luck

Praful

 

[kaandee]

hi any body have any papers and design model of patch/ spiral antenna fed by microstrip line.

if you have can you send it to my mail: kallyany@gmail.com

Thank you