How does antenna aperture size affect performance?

[Hamidzia]

Antenna Aperture

Assalam O Alekum !

How does Antenna Aperture size (increasing or decreasing)
effects the following individually

1. Power reqd. for transmission
2. bandwidth
3. noise
4. efficiency


and on the whole the antenna performance.

 

[jako123]

Re: Antenna Aperture

a look here:


hxxp://k9erg.tripod.com/theory.htm

 

[batdin]

Re: Antenna Aperture

1.decreases
2.narrower for phased arrays;otherwise the same
3.what do you mean by noise?Thermal noise depends on where the antenna points to.In phased array antennas it can increase because of the increased losses.
4.normally decreases for phased array antennas,the same for reflector antennas

 

[Hamidzia]

Re: Antenna Aperture

Dear Batdin

Thanks

do u have some document regarding this or any book that
contains this knowledge.
So that i could get a better idea with some details.

 

[si14]

Re: Antenna Aperture

tanx dav.

 

[sonal]

Antenna Aperture

As a receiver, antenna aperture can be visualised as the area of a circle constructed broadside to incoming radiation where all radiation passing within the circle is delivered by the antenna to a matched load. (Note that transmitting and receiving are reciprocal, so the aperture is the same for both.) Thus incoming power density (watts per square metre) x aperture (square metres)= available power from antenna (watts). Antenna gain is directly proportional to aperture. An isotropic antenna has an aperture of (wavelength)²/4π, and one with gain G has an aperture of G.λ²/4π

Generally, antenna gain is increased by directing radiation in a single direction, while necessarily reducing it in all other directions since power cannot be created by the antenna. Thus the higher the gain, the larger the aperture and the narrower the beamwidth.

Large dish antennas, many wavelengths across, have an aperture nearly equal to their physical area.