Investigation of new concepts for designing millimetre-wave antennas

The problem associated with the design of microstrip antennas and arrays at millimeter wavelengths is addressed and the dominant difficulties identified as line loss, tolerance effects and integration or connection of the antenna to the rest of the equipment using launching transitions. Several types of the latter are evaluated and measured to illustrate loss and cross-polarization effects. Methods for reducing line loss are investigated but the reductions are not significant. The findings are summarized and related to current military requirements. An alternative structure, and hybrid microstrip dielectric array is described and in principle enables array feeder loss to be appreciably reduced but launcher loss remains the major obstacle. Conclusions and recommendations are given and it is evident that microstrip continues to be attractive for some military applications where planar conformal smaller size arrays are required.