Ground Tests on MLS Elevation Subsystem
1986 Volume 1986 Issue 53 Pages 31-51
Details
1986 Volume 1986 Issue 53 Pages 31-51
The SARPs (Standards And Recommended Practices) for MLS (Microwave Landing System) are being established as ICAO standard. The research and development tasks on MLS have been performed to obtain data for its installation and operation.
This paper describes the ground tests and simple environmental tests, using MLS elevation subsystem and a ground test van at Sendai airport.
The MLS elevation subsystem employs a full solid state 15 W transmitter. Beam pattern of the scanning antenna is shaped, for vertical plane, 1.5 degree beam width and the centerline emphasis characteristics is used for holizontal plane.
The ground tests are carried out to investigate the performance of the subsystem and the multipath propagation problems. The location of the scanning antenna is chosen so that the error characteristics with and without the multipath wave from buildings can be measured at same site.
The elevation angle error without the multipath wave, 0.04 degree (2σ) stays at about 1/3 of the ICAO specifications. Large angle errors are observed due to the multipath wave by the buildings nearby. However, if the scanning antenna with the centerline emphasis pattern did not be employed, the errors would become much larger in the multipath region.
The environmental test results indicate that the static angle error is affected significantly by the heavy rain falls and the operation period of the air conditioner in the scanning antenna.
The results obtained here are expected to be the basic data to give MLS elevation subsystem specifications, siting criteria and operational procedures.
