return loss at 0 frequency?

[rameshrai]

Hello,

My inset fed patch antenna simulation shows return loss of -12.5dB at 0 frequency. attached pic shows the problem. I have changed almost all parameter(gap, fed width and fed length etc) to bring it up to 0dB but it is not happening.

How can I bring it up,

looking forward for advice

thanks,
ramesh

 

[biff44]

well, what is your bandwidth at 0 hz?

 

[chiques]

0Hz ~ DC, ???

 

[chiques]

FYi your attachment is flagged by the forum admin and we can't open it. You might want to fix it.

 

[rameshrai]

Hello,

the picture is attached properly now

Yes, the return loss is high at DC, the bandwidth can be seen from the figure

If somebody had such experiences, please share

thanks

 

[FvM]

What does return loss at 0 Hz matter at all?

You didn't tell how you achieved the results, we just can assume that the loss curve is plausible according to your antenna design and/or simulation setup.

 

[BigBoss]

Every EM simulator has a lowest limit.DC is not included in simulation limits.
It's normal, the simulator made an extrapolation even it's wrong..

 

[rameshrai]

thanks bigboss, FvM....

Can we bring this up changing the value of gap between the microstrip and the antenna?

do we have a formula for calculating the gap? mine was a random guess.

thanks

 

[biff44]

you do not seem to understand that we are making fun of your post. There is not such thing as a "return loss" at 0 frequency.

 

[rameshrai]

Initially, I thought it was the gap between the microstrip and the patch because I had put a guess value for the gap as I didn't find any good supporting theory. but as all of you pointed out specially bigboss that the curve at dc seen is not a much of concern i know now this.

I want to get confirmed about the gap, what is the best gap value, if there is any?

thanks