Slot Antennas

The development of flush-type radiators of the slot and pocket type is described. Special emphasis is given to types applicable to aircraft. Specific solutions to altimeter and marker beacon pickup antennas are described. Reference to application in other fields is also made. The general aspects of the phenomena which are involved are examined, and it becomes evident that workable solutions, in the majority of cases, can be obtained only by means of actual experiment, since variations in the surroundings have first-order influence upon such vital characteristics as radiation patterns, slot impedance, and bandwidth. Progress before and during the war is described in somewhat chronological manner. It is pointed out that, while this progress has been considerable, an appreciable amount of skillful investigation remains to be done before slot antennas can be brought to maximum usefulness.