Inside Wireless: Radiation Diagram

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In this Inside Wireless episode we speak about radiation diagram basics. The radiation diagram describes how strongly an antenna radiates in any direction. It is also called radiation pattern and it’s one of the essential parameters of an antenna. Why? Because the shape of radiation diagram determines the application of an antenna.

Antennas smoothly spread the energy in three dimensional space. Displaying this would be extremely difficult without powerful computers and 3D graphics back in the time. Therefore, scientist introduced simplified method to describe the radiation pattern: two dimensional plots. And we stick with this method until today.

The density of the color on a radiation pattern corresponds to the energy level. With directional antennas, we call the axis of maximum gain (maximum radiated power) the Antenna Boresight. For directional antennas the boresight is usually the axis of symmetry. Boresight typically marks the 0 degrees of the radiation pattern. Measuring the antenna gain at every angle of a sphere, we get the 3D radiation pattern. If we cut the 3D diagram in horizontal plane, we call it azimuth cut, if we cut the diagram in vertical pane, we call it elevation cut. The result is probably the most common plot and it is called Polar plot.

Polar plots shows how gain changes with angle on a single slice of the 3D radiation pattern. The numbers around the outer circle represent the angular direction of radiation. The inner circles represent the axis that shows antenna gain. To read the angle at any point in the diagram, connect it with the center of the polar plot and see where the line intersects with the outer circle scale. The gain value is read by looking where the point on the plot intersects with the inner circles.

Because of 360 degree visualization, polar plots provide easier overall picture, but it may be difficult to read exact values due to the circular gain axis. Solution? Let’s straighten the circular gain axis and we get the X-Y plot.

X-Y plot has two axes: x for angle and y for gain. Gain at a particular angle is read by intersecting the point on the plot with the axes. Now isn't that easier :)

Two dimensional graphs are OK to describe simple, clean and symmetrical radiation diagrams, just like symmetrical horn antenna. But remember, that the limitations of two dimensional interpretation are huge when describing complex radiation diagrams, or non symmetrical radiation diagrams, where two cuts are simply not enough to describe them.

0:00 intro
0:25 Radiation pattern explanation
1:06 Azimuth & elevation cuts, polar plot
1:29 XY plot

#RFelements #Insidewireless #radiationpattern #radiationdiagram #Antennas #SaveSpectrum #RejectNoise #growsmart #UbiquitiNetworks #CambiumNetworks #MimosaNetworks #Mikrotik

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Rfelements

Straight to the point, easy enough to understand. Thanks for sharing.

charleschoy

hai pak. agar mendapatkam sinyal yang stabil dan baik. memilih antena berapa dbi yang baik? untuk alat wifi outdoor terhubung langsung ke handphone?

herinettv