No abstract

We proposed an optically controlled phased array antenna using a spatial light modulator for an adaptive satellite communications system. We have developed a prototype of an Optical Beam Forming Network, which enables control of 2 beams individually, and demonstrated at Ka band. We confirmed a good agreement between theoretical antenna patterns and calculated antenna patterns, which are simulated by using measured amplitude and phase distributions of the prototype.

SUMMARYThe characteristics of metal cavity-attached resistorloaded bow-tie antennas, which are widely employed as antennas for subsurface detection radars using broadband pulses, are investigated theoretically and experimentally in this paper. Two kinds of antennas are considered: isolated antennas having a structure which separates electrically the bow-tie antenna and the metal cavity, and connected-type antennas which connect the bow-tie antenna and the metal cavity via a resistor. The inner cavity surfaces of both types are coated with ferrite. In this paper, the characteristics of both types of antennas are discussed from the point of view of the effects of the ferrite absorber on the above-ground and subsurface underground radiation power, the coupling between the transmitter and the receiver, and the effects on the transient reception characteristics. The reasonableness of the analysis of the ferrite absorber is verified experimentally.