Ryuichi Iwata

Stub switched phase shifter

A stub switched phase shifter, which consists of a reference line, a delay stub and fewer RF switches than the switched line phase shifter, is proposed. It has low phase deviation characteristics. Especially, for the condition of /spl Phi/=180/spl deg/, S=0, L=1/2/spl lambda/g/sub 0/, the proposed phase shifter can reduce two RF switches, and is as compact as about 40% the size of a conventional switched-line phase shifter. It is suitable for phased array applications. The characteristics of the proposed phase shifter designed for /spl Phi/=90/spl deg/, 180/spl deg/ were confirmed by the method of moments.

Analysis of phased arrays of printed microstrip patches with parasitic elements

The mutual coupling effect in phased arrays of patch elements on relatively high permittivity substrates is discussed. Mutual coupling properties of a single layer (un-stacked) patch and stacked patches with/without an air layer are compared for both port coupling and re-radiation level. To estimate the mutual coupling effects in 2-dimensional array environments, 4/spl times/4 element arrays are simulated.

Composite parabola dual beam antenna with a phase compensation subreflector

The author describes a dual-beam antenna, using a composite parabola with a phase compensation subreflector, which can simultaneously access two adjacent geostationary satellites. A dual-beam antenna is preferable for a satellite ground station, since the main reflector is smaller than two single-beam antennas and a minimum number of reflectors is required. An experiment was performed with a 1.27-m diameter antenna, operating in the 39/35-GHz frequency bands. The experimental data, which agreed well with the calculated data, demonstrated the validity of the design procedure and analyses. The proposed antenna uses a single main reflector subreflector configuration with the main reflector diameter only 5% larger than that of a single-beam antenna. The composite dual-beam antenna is also capable of tracking the drift of a satellite in geostationary orbit.<<ETX>>

180/spl deg///spl alpha//spl deg/ combined phase shifter

Strip line phase shifters are key devices widely used in phased array antenna application. To avoid the grating-lobes through a wide range of scanning angle, the element spacing in the array should be less than about /spl lambda//2. In order to arrange all of the phase shifters in the phased array antenna on a single plane, each phase shifter should be as compact as possible. The digital phase shifter composed of cascaded several bit elements (180/spl deg/, 90/spl deg/, 45/spl deg/, 22.5/spl deg/...), is widely used for phased array application. We propose 180/spl deg///spl alpha//spl deg/ combined phase shifter, which consists of 180/spl deg/ switched-line section and arbitrary angle (/spl alpha//spl deg/) loaded-line section. This proposed phase shifter operates as a 2-bit phase shifter, and has both physical and electrical advantages, i.e., its compact size and small phase shift deviation. This paper presents the basic configuration of the proposed phase shifter, and also presents an example of the characteristics in the case of a /spl alpha//spl deg/=45/spl deg/ calculated by the method of moment.