Time Reference Scanning Beam Microwave Landing System (TRSB-MLS) was selected by ICAO All Weather operations Panel in 1978 as the preferred system for a new nonvisual Precision Approach and Landing Guidance System (PALGS) in place of the present ILS and is now under development.

The TRSB-MLS ground station scans its beam discretely for angle guidance, and hence the received waveforms are stair-case patterns contaminated by beam pointing errors. This degrades the angle guidance accuracy of the TRSB System without an adequate waveform shaping at the airborne receiver.

This paper describes computer simulation of bandwidth limiting effects on such received waveforms and explains the obtained relations between angle measurement errors, antenna stepwidth, pointing accuracy, and receiver bandwidth.

As a conclusion, we found out that the pointing accuracy is more important than the scan stepwidth in the design of the scanning antenna.

Also mentioned are the effects of the increase of scan stepwidth on in-beam-multipath errors, and tolerable stepwidth and receiver bandwidth under in-beam-multipath environments.

These relations are useful in the design of the TRSB-MLS ground antenna and airborne receiver.

Balanced design is required for a new counterpoise for the sheltered VOR to make the construction period shorter.

Weather durability is also an important facfor for the design and hence, a snow-fall test was made together with a mechanical load test.

A counterpoise was designed based on these results and installed at Sendai Airport for performance test, both ground and flight check, which yielded satisfactory data clearing ICAO specified data which were listed in Annex 10 Attmt. C.

Also, the construction period was halved from 4 months in the case of the conventional method to 2 months.