Phase variations in a monopulse antenna
Abstract
It has been found that in an amplitude-comparison monopulse radar with a parabolic reflector, the normalized error signal (ratio of difference signal to sum signal) can have a quadrature-phase as well as an in-phase component, even for a point target without multipath or interfering signals. This fact was first revealed by tests and has now been confirmed by analysis. The quadrature-phase component is very small within about one-half beamwidth of the antenna axis but can become significant at larger angles. It is attributed to the fact that the individual feed horns are necessarily displaced from the axis of the reflector. Plots of the amplitude and phase of the electromagnetic field in the focal plane provide insight into the effects of feed-horn size and position. These findings have little or no effect on ordinary closed-loop tracking of a single target in free space, but should be taken into account when the response of a radar to multipath or unresolved targets is calculated, especially at short range.
- Publication:
-
International Radar Conference
- Pub Date:
- 1975
- Bibcode:
- 1975inra.conf..354N
- Keywords:
-
- Error Signals;
- Monopulse Antennas;
- Parabolic Reflectors;
- Phase Shift;
- Radar Antennas;
- Tracking Radar;
- Antenna Design;
- Antenna Feeds;
- Feedback Control;
- Focal Plane Devices;
- Horn Antennas;
- Monopulse Radar;
- Multipath Transmission;
- Communications and Radar