1980 Volume 1980 Issue 24 Pages 31-51
This is a report on a high performance of a prototype open planar array SSR antenna (OPA) made by Electronic Navigation Research Institute (ENRI) from 1976 through 1978.
The Japan Civil Aviation Bureau (JCAB) has a plan of installing the second radar (ASR/SSR) at New Tokyo International Airport (Narita) to enhance air traffic safety. The second radar site is close to a cargo area where several B747s are to park. It was therefore evident that parked B747s would cause a serious trouble to the radar. JCAB asked ENRI to see if OPA would alleviate the trouble.
An experiment was then carried out at Iwanuma. A metal net screen, 10m x 12m, was set up vertically and another one, 12m x 12m, was placed horizontally on the ground. Both the screens were connected in L shape to represent the empennage of the B747, and then placed 104m away from the radar station so that the first sidelobe of OPA would hit it. This is shown in Figure 9. Interrogations from OPA would be effectively reflected and cause false targets with replies from aircraft transponders. The purpose of the experiment was to evaluate effectiveness of OPA in comparison with a conventional SSR antenna at Narita or a trouble simillar to that.
The following were used for data collection: the Beechcraft B-99, ENRI aircraft for airborne experiments, a photographic radar recorder, and the data analysis system composed of a monopulse receiver, a beacon video digitizer, two TOSBAC/40s, two magnetic tape recorders, two typewriters, a plan view display, and a character display.
Data on false targets caused by reflections with the screen were obtained on both OPA and the conventional antenna, respectively. As the result of the experiment, the data showed that OPA ensured a marked improvement of 87% in flase targets reduction. Such a high performance of OPA results from its sharp cutoff vertical pattern with 2dB/degree at the horizon.
