STK Antenna Models

Bessel Envelope Aperture Circular Antenna

Antenna pattern envelope is the asymptotic form of the Bessel pattern, using the null pointer. This antenna uses a polar coordinate system.

Field Description
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.
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.
Main-Lobe Gain The main-lobe gain value. Valid if Computed is not selected. Select Computed to automatically calculate the main-lobe gain based on beamwidth or diameter, efficiency, and design frequency.
Efficiency The antenna efficiency factor, ranging from 0 to 100 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.
Function Power An integer for the exponent. The value must fall in the range 0-3.
Pedestal Level The edge taper value for uniform distribution.
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