Why do I get antenna gain in dBi in HFSS 11?

Hi Everybody,

I run simulation of microstrip antenna in HFSS 11. I expect to get a gain of antenna at most 10 dBi but when I use Results ----> Create Far Fields Report -------> Rectangular plot ----> Etheta ----> dB I get about 20 dB. It could not be in dBi.
In HFSS 10 I would get this quantity in dBi but in HFSS11 I dont understand why it doesn't .

Please if anybody knows write it down.

Thanks

gain dbi in hfss

Why don't you use Gaintotal instead of Etheta in HFSS, to find the gain of the antenna?

dbi in hfss

Yes, Zottiri pointed out the error. Gain and the electric field are different quantities. You can relate E field to gain by E = sqrt(2*Z0/(4pi)) * Gain where Z0 is the intrinsic impedance of medium surrounding the antenna which is usually air for which its value is 125*pi

So when you get an E field of 20 dB the gain is close to 6 dBi.

And you are just looking at just the theta component. So this means your theta component of gain is around 6 dBi. I believe you are looking for gaintotal instead.

retheta hfss

Hi Everybody,

I am using HFSS11 betta. In the menu Far Field there is no option of Gain,
but there is rETotal, rETheta, rEPhi. The reason that I use ETheta is that I am interesting just in that component. In HFSS 10 or 9 there isn't such a problem. It gives a gain in dBi. I am almost shure that there is some option that I can get a Gain without doing some post-procesing calculation.

Thank's

plot gain dbi in hfss

Could it have anything to do with the fact that it is a beta version? I haven't seen something like that with the proper HFSS 11 version. And I don't see why it cannot calculate gain when it can calculate E field.

See if HFSS computes the antenna's peak gain under 'Compute Antenna Parameters'?

gain dbi with hfss

Hi vv1234, if you want to plot the TotalGain, you should to this:

Results -> Create Far Field Report ->Rectangular Plot -> and choose Gain on menu "Category".

I have the Beta version too, and i can plot the Gain.

I hope that help you.

hi all,

i am simulating a patch antenna on hfss for fr=2.4Ghz,

i m getting return loss as -20 dB, but the gain is coming to be nearly 0 dB???????????


how i can increase the gain to 6 to 7dB

thank you all

waiting for reply

Hi, can you start a new topic for this?
And use the search function, there are a lot of posts for patch antennas in this forum.

At first i had a problem understanding dbi and db. After much reading and trials, i finally understood what it meant.

Actually, when you do a simulation in HFSS, you won't see a dbi term. But rather you see a dB term. What it exactly meant is that HFSS actually compared the gain to an isotropic antenna. For your info, isotropic antenna is actually an ideal antenna which emits gain of 1 (absolute value) equally in a sphere form. So the gain in dB of an isotropic antenna is 10log(1) = 0dB.

So the dB you get from your HFSS simulation is actually the real value of the antenna gain and it's auto compared to a isotropic antenna so you can assume it's equivalent to a dBi form.

The gain of antenna is not actually the gain of the antenna itself, but its always a comparison of gain towards another antenna. So once you get your gain in HFSS simulation results in dB result, you can equate it in dBi. So when you do a real time measurement in an anechoid chamber, you realise that there's no such thing as an ideal antenna. So you will have a transmissiting antenna (could be anything) sending signals to your fabricated antenna (receiver).

When the measurement ends, you can see the network analyzer will show your gain in dBi format which actually meant that your antenna in comparison to the receiver is how much less or how much more. dBi doesn't mean the gain value entirely, it's just the difference of gains between 2 antenna.