omni antenna gain

Is there any relation between the gain and the length , i mean in the same frequency band if we increase the length we will get better gain ! this is what i saw in some antenna manuals .

or may be it depends on the material that the antenna made from?

There is no direct relation between antenna length and gain, but it is between antenna aperture (or effective area) and antenna gain.

The gain is proportional to the aperture area and inversely proportional to the square of the wavelength.

For example, if the frequency is doubled, the aperture could be decreased four times to maintain the same gain.

The material of the antenna could affect the antenna efficiency.

Mr. vfone
what do you mean by aperture area ? is it related to 3 db angle ?


and for the reason of aperture area the dimensions of base station antenna is bigger than the dimensions subscriber antennas ?

Antenna Aperture is direct related to its area and is measured in m2

Is true, there is also a relation between Antenna Aperture and beam angle:
Aperture = λ2/(Beam_angle)
or, larger the area, smaller the beam angle.