Resonant and Non-resonant Linear Slot Arrays

Abstract

Antenna arrays and the devices, components and techniques, which have evolved to implement them, form a very large subdivision of the antenna literature. Here we concentrate on those elements of the topic which are relevant to slot array antennas particularly those that exhibit compact forms. The essence of array behaviour can be deduced most efficiently by examining linear arrays of isotropic radiators. Given that, as we have seen, the relationship, theoretically, between an isotropic radiator and a slot radiator is well established, it is not difficult subsequently to generate patterns for arrays formed from slots. Fortunately, planar arrays, which are more difficult to analyse directly, can largely be viewed as combinations of linear arrays. The majority of the chapter is directed at developing and using well established polynomial techniques which now underpin array analysis and synthesis procedures. The techniques discussed apply predominantly to those arrays where the elemental radiators are separately excited from a multiplicity of sources which can be controlled individually in frequency, radiation phase and magnitude. Equally, they can also apply to arrays fed from a single source through a complex multiply-branching power distribution network with each radiating element backed by a phase shifter and/or a power attenuator to provide flexible control of radiation phase and magnitude. Array radiation patterns and their dependence on element numbers, element spacing, element weighting and phase are discussed mainly with reference to pattern directivity, pattern gain, beamwidth, mainlobe direction, sidelobes and grating lobes.