STK Antenna Models

Cosine Aperture Circular Antenna

Cosine curve distribution pattern with a circular pattern of illumination, illustrated by the red curve below.

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

This is the frequency of the antenna. The antenna design frequency is independent of the operational frequency of a transmitter, receiver, or radar. Changing the frequency of a transmitter, receiver, or radar does not update an embedded antenna's design frequency, nor vice versa. The design frequency is solely used at antenna configuration time to compute the antenna size from its max gain or beamwidth settings. A mismatch between signal frequency and antenna design frequency typically causes performance degradation.
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 You can use back-lobe gain 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.