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

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.

Please note that you will not see a change in link performance when the antenna is set to Dimension.
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 You can use Back-lobe gain in 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, STK applies the attenuation factor on the main-lobe gain and uses the result in the back-lobe direction.