Shigeo Kawasaki

Quasi-optical planar arrays with FETs and slots

This work describes the design concept and experimental results for prototypes of two-dimensional quasi-optical power-combining arrays. Several different quasi-optical circuits were used to obtain the fundamental data for this study. How to incorporate the antenna input impedance into the active antenna circuit and how to analyze the strong coupling condition with two operating modes are addressed using large-signal analysis. Several circuit configurations are demonstrated, including a single active antenna operating at 9.3 and 24.0 GHz, a six-element linear power-combining array operating at 15.6 GHz, and four-element and sixteen-element two-dimensional power combining arrays operating at 10.4 and 7.8 GHz. Important characteristics such as antenna patterns and tuning ranges are discussed. The prospects for a two-dimensional monolithic quasi-optical power-combining array are discussed. >

Transponder using self-oscillating mixer and active antenna

A new planar transponder integrating a self-oscillating mixer (SOM) and active antennas is presented. The receiving active antenna combines a FET SOM with a patch antenna and the transmitting antenna is combined with the IF amplifier. The transponder was successfully operated up to 2 m. The design concept and the experimental result are discussed.<<ETX>>

A novel FET model including an illumination intensity parameter for simulation of optically controlled millimeter-wave oscillators

This paper demonstrates an illuminated FET model including an illumination-intensity parameter for simulation of optical characteristics of microwave and millimeter wave integrated circuits (MMICs). Modeling for an illuminated GaAs MESFET and an InP high electron-mobility transistor (HEMT), and analysis and experimental results from optically controlled microwave and millimeter-wave hybrid integrated circuit (HIC) and MMIC oscillators are discussed. The proposed illuminated FET model was able to explain the photoresponse of both the GaAs MESFET and the InP HEMT, and the photooperation of their circuits.

40 GHz quasi-optical second harmonic spatial power combiner using FETs and slots

FET oscillators integrated with slot radiators are used for constructing quasi-optical second-harmonic spatial power combiners. Double-oscillator power combiner circuits with a strongly coupled structure generated the 40-GHz second-harmonic frequencies. The radiation patterns of the double-oscillator power combiners are also discussed. Through the antenna patterns obtained one can also find information on the phase relationship between the oscillators. By controlling the phases on the slots, it was possible to obtain the Delta pattern for the 19-GHz fundamental and the Sigma pattern for the 40-GHz second harmonic.<<ETX>>

Laminated active integrated amplifier antenna arrays for a space solar power satellite

In this paper, as one example of an application of the active integrated antenna technique, a design method and experimental data of the active integrated amplifier antenna array are reported for microwave power transmission in the Space Solar Power Satellite 2000 system. The stacked structure of a unit cell in the array proposed here consists of three layers: the amplification circuit layer, radiation layer, and coupling layer. By incorporating 2/spl times/2 unit cells with the combination of a directional coupler and an FET amplifier, a light unit patch plate with weight of 200 g and effective radiated power of 25.6 dBm is fabricated and operated at 2.45 GHz.

Optical Control of Active Integrated Antenna

The reactance of MESFETs in the active integrated antenna are controlled by illuminating with a laser or a fiber illuminator. For the slot antenna with reactive FETs operated by an external source, the optical tuning range of 110 MHz was obtained at 10 GHz. Further, for the quasi-optical oscillator using a MESFET and a slot radiator, the unoptimized optical tuning range of 10 MHz was achieved.

Optical control of MMIC oscillators and model parameter analysis of an illuminated FET at the Ka- and V-band

This paper reports experimental results of optical control of millimeter-wave HJFET MMIC oscillators and FET model parameter analysis with illumination. Using a noncoherent optical source, the maximum optical tuning ranges of 32 MHz around 30 GHz and 260 MHz around 51 GHz were obtained. By means of parameter extraction, a 46.6% increase in Cgd and a 19.1% decrease in Cds due to the illumination and their frequency dependence were appreciated.<<ETX>>

2*2 quasi-optical power combiner array at 20 GHz

The design concept and the experimental results for a power combiner made of two strongly coupled FET oscillators use in a quasi-optical array are reported. To demonstrate the approach, a 2*2 planar array has been fabricated using a direct connection through a microstrip line. Taking the input impedance of the slot radiator into account, circuit the passive part of the array is investigated. The length of the microstrip feed lines are regulated to achieve the desired sum radiation pattern. At an operating frequency of 20 GHz, sum radiation patterns have been observed in both the H-plane and the E-plane. >

Topology of laminated active integrated antenna arrays

Two types of laminated active integrated antennas were demonstrated in this paper. One is the 3-element linear active integrated antenna array with an FET oscillator and a planar slot antenna laminated by a dielectric slab for reduction of antenna size. In the second type, incorporating the oscillator feedback loop with a directional coupler, the two-element laminated active integrated antenna array operated by trimming an injection signal for beam steering. These active integrated antennas were designed to satisfy with the requirement of increase of receiving power as well as beam operation.

Characteristics of optically controlled oscillator using InP HEMT with novel structure

This paper demonstrates the characteristics of the novel structure of photonic HEMT and the optical tuning characteristics of the MMIC oscillator using novel HEMT. The novel HEMT has an optical absorption layer to increase the photo-response. The fabricated oscillator consists of a InP HEMT and a CPW. The optical frequency shift of the InP MMIC oscillator using novel HEMT with 1.5 /spl mu/m optical source was 180 MHz around 37 GHz. It was found that enhancement of the optical tuning with the 1.5 /spl mu/m laser can be realized using a HEMT with novel structure.