STK Antenna Models

Parabolic Antenna

An analytical model of a uniformly illuminated parabolic antenna, shown below.

This antenna uses a polar coordinate system.

Field Description
Design Frequency

The frequency of the antenna.

For an embedded antenna on a receiver, transmitter or radar, this value corresponds to the Frequency entered on the Model Specs tab for the transmitter or receiver and the Transmitter Specs tab for the Radar.

For an antenna linked to a receiver, transmitter, or radar, the Antenna Design Frequency value gets overridden by the Frequency value set on the Model Specs tab for the transmitter or receiver, and the on the Transmitter Specs tab for the Radar. However, when computing the antenna's gain matrix (or a link budget, etc.) from one of the objects linking to the antenna, that other object's frequency settings override the antenna's Design Frequency setting.
Beamwidth The beamwidth of the antenna gain pattern. Valid if Use Beamwidth is selected. The diameter and gain are automatically calculated on the basis of this value and the frequency.
Diameter Diameter of the dish. Valid if Use Diameter is selected. The beamwidth and gain are automatically calculated on the basis of this value and the frequency.
Main-Lobe Gain Select the Use Max Gain option and enter the value in dB. The diameter (or dimension) and beamwidth are automatically calculated on the basis of this value and the frequency.
Efficiency Specifies the efficiency factor of the dish, varying from 0 to 100 percent. Since no antenna is perfect, the efficiency factor allows you to specify the degradation in performance. Typical values fall in the range of 50 to 75 percent.
Back-lobe Gain Back-lobe gain can be used two different ways:
  1. A constant gain value from 90 to 270 degrees in elevation from the boresight of the antenna.
  2. Modeled as a fraction of the Main-lobe Gain, but in the opposite direction. For example, boresight gain is computed at a 0 degree elevation angle, the back-lobe attenuation factor is applied and the result is used as the gain at the 180 degree elevation angle. The backlobe gain is a mirror image of the forward gain, but with the backlobe gain applied as an attenuation factor. If “Use as main-lobe attenuation” is selected, the attenuation factor is applied on the main-lobe gain and the result is used in the back-lobe direction.
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