Is there a relationship between antenna gain and frequency bandwidth?

[kae_jolie]

I can't find a direct relationship or equation between antenna gain and bandwidth in the literature. Is there a relationship?

In my simulations, I do observe that as bandwidth of antenna increases, gain in general decreases.

Could someone explain the relationship between the two physically?

Thanks.

 

[Terminator3]

When bandwidth increased, then antenna (or part of it) can not resonate at full power at some frequency. I think relationship is something near formulas about oscillation modes and wavelengths.

 

[zorro]

In general, there is no direct relationship.
Although, for some particular type of antenna and bandwidth-enhancement technique, it can be true.
Regards

Z

 

[flanello]

The gain is frequency depend, so you can get from the same antenna more gain at a higher frequency than at a lower.
This could lead to different gains at different frequency points, and perhaps decreases the antenna gain from an antenna with a very large bandwidth.

By the way, what gain is stated from an antenna with large bandwidth? The lowest?

 

[drkirkby]

In general, there is no direct relationship.

Z

I believe you are wrong. There is a theoretical limiting relating the Q (which is related to bandwidth), gain, and the volume of a sphere enclosing an antenna

**broken link removed**

That said, I think there is no practical way to get near this maximum theorectical value.

Dave

 

[jeeudr]

That page seems to list a few very interesting articles.

Though, it does seem to make some restrictions: linear polarized, omni-directional ?

 

[zorro]

I believe you are wrong. There is a theoretical limiting relating the Q (which is related to bandwidth), gain, and the volume of a sphere enclosing an antenna

Hi Dave,

It't true that there exists such a limitation between antenna size and bandwidth. But what I said is that In general, there is no direct relationship between antenna gain and bandwidth. I.e., there is no a general rule that can be applied to all cases.
Regards

Z