Quote:
Originally Posted by er1cdotnet
When does one worry about gain vs. aperture?
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In general, gain is the only parameter you need to worry about.
Just because an antenna has a large physical aperture doesn't mean that it's going to have a high effective aperture. See
http://en.wikipedia.org/wiki/Antenna...ure_efficiency.
Gain is directly proportional to the effective aperture of an antenna, so essentially, they represent the same thing. However, you should not confuse physical aperture with effective aperture since the aperture efficiency can vary a lot between different antenna designs.
Gain is gain, no matter how it was achieved. With this parameter alone, you can compute how much signal power is going to be delivered to the antenna terminals.
In some cases, you may also want to know the radiation pattern of the antenna. If you have some off-axis interfering signals that you want to block out, you'll want to take a look at where the "side lobes" of the antenna pattern are relative to your desired signal.