Is antenna gain unit dBi or dB in HFSS results?

[tony_lth]

Hi, Gurus,
In HFSS design, the radiation is a "Infinite sphere1", with theta and phi both from -180deg to +180deg.
Then I get a results with dB(RealizedGainTotal) at phi=0 and theta=0.
I want to know what is the unit for my result, dB or dBi?
My concern is such as in FCC document, it says that EIRP peak should be less than +55dBm.
So should I use my result dB value directly or add some 2.15dB or substract 2.15dB, when I evaluate the FCC requirement?
Best,
Tony Liu

 

[PlanarMetamaterials]

Gain (specifically, Directivity) always has to be measured relative to some kind of source. In HFSS, I believe this is always dBi (even though it just says "dB"). You could check by simulating a dipole, which should have about 2.15 dBi of directivity.

In this case, you shouldn't have to subtract or add anything from the gain value. However, take care that your calculation specifies either gain in dB(i) or linear terms.

 

[volker@muehlhaus]

Antenne gain in simulators is dBi (reference=isotropic antenna)