Leaky-wave antennas using artificial dielectrics at millimiter wave frequencies

Abstract

The feasibility of freguency scanning and dielectric scanning {changing the direction of the bearn by varying the relative permittivity of the electrically controlled liquid artificial dielectric medium) of a leaky-wave antenna using rodded artificial dielectric is investigated theoretically. From Table l it is noted that for small scan ranges, the frequency scanned antenna (FSA) has less variation in the bearnwidth as compared to the dielectric-scanned antenna (DSA) . The gain of a dielectric-scanned antenna is greater by about 0.8 dB over the frequency-scanned antenna. Efficiency is more or less the same for bath the types in the case of small scan ranges as well as for large scan ranges. For large scan range (lO°-55°) the maximum and minimum gains of DSA are 21.0 dB and 19.2 dB respectively cornpared to 20.2 dB and 17.0 dB for the FSA. It is thus noted that the FSA has more variation in the gain of the antenna in comparison to the DSA. Variation in the beamwidth is almost the same for bath techniques, although the DSA has about 15% less beamwidth than the FSA. Thus it may be concluded that for large scan ranges, a dielectric-scanned antenna has better scanning characteristics than a frequency-scanned antenna. It is also found that the present structure (AD) is rouch more dispersive than the insular guide studied for frequency scanned arrays, silicon waveguide with metallic stripe perturbations used for frequency scanned antenna and inverted strip dielectric waveguide, when the same dielectric material is used.