Dispersion characteristics of wide slotlines on thin dielectric substrates in a two dimensional phased array environment

Constant width slot antennas(CWSA) and various types of tappered slot antennas(TSA) have attractive features like ease of construction, compatibility with MIC/MMIC technologies, Wider bandwidth,… for focal plane and phased array applications. Radiation and input circuit characteristics of a single isolated TSA/CWSA element has been investigated by several workers, but there are relatively few published works dealing with its behaviour in an array. The reports reflecting recent progresses in TSA array or subarray technology, for example, very interesting review of current art presented in(1) have based their studies on single element characteristics. Interaction between neighboring elements especially when the spacing between them is less than half a wavelength, has significant effects on element characteristics and the array as a whole. Important parameters such as pattern shape, beamwidth, bandwidth, S.L.L, directivity, and gain are quite sensitive to small variations in propagation constant along the antenna (2),(3). Consequently the knowledge of this parameter or equivalently the guided wavelength as a function of frequency and the other physical parameters of a uniform(CWSA) or nonuniform(TSA) structure in an array configuration is crucial for theoretical prediction of the system performances. For this purpose, mutual effects which are not fully understood yet should be taken into account properly.