Antennae radiation patterns

In summary: That might be cool if you could figure out how to display it.In summary, the radiation pattern for an isotropic antenna is uniform in all directions, resembling a sphere. However, there is no formula for determining the diameter of the sphere as it is meaningless in this context. A ground plane, when placed below the antenna, can affect the pattern by reflecting the signal and making it push up in certain directions. This is more applicable to realistic antennas like a dipole, which have horizontal lobes and no vertical pattern. By adding a ground plane, the lobes can be pushed up at an angle. However, for an isotropic antenna, the only way to make the sphere meaningful would be to create concentric spheres representing signal strength.
  • #1
ionlylooklazy
30
0
ok, so for an isotropic antennae the radiation pattern is uniform in all directions (i.e. a sphere). So for this pattern, is there a formula for determining the diameter of the sphere, or is such a measurement meaningless?

also, suppose a ground-plane an arbitrary height below the antennae, the ground plane would reflect the signal and look something like this??
 

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  • #2
The diameter of the sphere is meaningless, as you say. The pattern distribution in that kind of drawing is meant to indicate power relative to angle. If the pattern is not isotropic, that means that more power goes in the direction of the bulges than in the other directions.

A ground plane does make the pattern push up something like that. I'm not that familiar with ideal isotropic antennas, since they aren't very real in most E&M situations. For a more realistic antenna like a dipole, when you see its pattern from the side, the lobes stretch out horizontally. There is no vertical pattern from a dipole. When you put a ground plane a wavelength or so below the dipole, it pushes up the side lobes so that they aim more up at an angle. I'll see if I can google some plots...


Edit -- I googled antenna pattern dipole ground plane, and got some good hits. Check this one out:

http://www.microhams.com/binfile/talks/Antennas%20Demystified.ppt#8 [Broken]
 
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  • #3
The only way for the sphere to be meaningful is if you make a bunch of concentric spheres corresponding to signal strength, much like a topographic map.
 

What are antennae radiation patterns?

Antennae radiation patterns refer to the directional distribution of electromagnetic energy radiated by an antenna. It can be visualized as a 3D plot showing the relative strength of the radiation in different directions from the antenna.

Why is it important to understand antennae radiation patterns?

Understanding antennae radiation patterns is crucial for designing and optimizing antenna systems for specific applications. It helps in determining the directionality, gain, and coverage of the antenna, which can greatly impact its performance.

How are antennae radiation patterns measured?

Antennae radiation patterns are typically measured using specialized equipment such as an anechoic chamber or a network analyzer. The antenna is placed in a controlled environment and its radiation is measured at various angles and frequencies to generate a 3D radiation pattern plot.

What factors affect antennae radiation patterns?

Several factors can affect antennae radiation patterns, including the type of antenna, its size and shape, the frequency of operation, and the surrounding environment. The presence of nearby objects or other antennas can also affect the radiation pattern.

Can antennae radiation patterns be manipulated?

Yes, antennae radiation patterns can be manipulated through various techniques such as antenna design, placement, and tuning. By adjusting these factors, it is possible to shape the radiation pattern to achieve desired characteristics for specific applications.

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