A wideband high power amplifier design using a novel band-pass filter with FET's parasitic reactances has been developed. The feature of this design is in that it can provide wide bandwidth and high gain of high power amplifiers. Furthermore, the lower cutoff frequency and bandwidth can be varied independently. With the use of this design, a Ku-band two-stage high power amplifier having a bandwidth of 18% has achieved a linear gain of 9.751.75 dB, a saturated output power of greater than 37 dBm, and a power-added efficiency of greater than 10.4%.

This paper describes a novel method to calculate the fields scattered by a polyhedron structure for an incident plane wave. In this method, the fields diffracted by an edge are calculated using the equivalent edge currents which are separated into components dependent on each of the two surfaces which form the edge. The separated equivalent edge currents are based on the Geometrical Theory of Diffraction (GTD). Using this Separated Equivalent Edge Current Method (SEECM) , fields scattered by a polyhedron structure can be calculated without special treatment of the singularity in the diffraction coefficient. This method can be also applied successfully to structures with convex surfaces by modeling them as polyhedron structures.

A multi-beam airborne pulsed-Doppler radar (MBR) system is presented and its clutter rejection performance compared with conventional phased array radar (PAR)'s by PRF tuning is discussed. The pulsed-Doppler radar equations taking account of the multi-beam operation are introduced and some kinds of computer simulations for seeking the conditions to get maximum signal to clutter ratio are carried out. As a results of this, it is cleared that same order of signal to clutter ratio improvement gotten in high PRF operation by conventional PAR can be realized at lower PRF operation by MBR on clutter free area, and higher clutter rejection effect, which is proportional to beam numbers, is obtained under affection of both of mainlobe and sidelobe clutters with order of beam numbers. This also means observable numbers of range bin are increased in MBR operation.

A Ka-band 0.5 W monolithic amplifier using a novel tandem FET has been developed. The tandem FET consists of two FET cells connected in series through a short transmission line. The features of the tandem FET are high gain, flat gain response and miniaturized size. The tandem FET is very useful for obtaining high gain, high power amplifiers operating in millimeter-wave region where combining and matching circuits' losses are significantly large. By combining four tandem FETs, a linear gain of 4.5 dB, a 1 dB compressed power of 26.3 dBm and a saturated output power of 27.3 dBm (0.54 W) have been achieved at 37 GHz. The size of the amplifier is 1.73.20.03t mm.

Coupling optics for a monolithic array LD module has been developed. High efficient and small sized confocal optics with aspheric lenses based on hyperbolic surfaces has been designed to achieve the uniformity of coupling loss. A small sized (7.2 cc) 4 channel array LD module with this optics was fabricated. This module has low (4.2 dB) and uniform (0.5 dB) coupling loss.