Slot antennas

Abstract

Great directivity can be achieved in the centimeter waverange (10 - 1 cm) which is the range of interest. This is possible because aerials (and aerial arrays) of quite a moderate size can be constructed to have dimensions large compared with the wavelength. Hence at these wavelengths it is possible to construct aerials designed to radiate power in narrow beams and it is this, which makes possible the two principle uses of centimeter waves, that is, radar and point to point radio links. It will be our aim in the work that follows to construct such an aerial. Since at these frequencies the normal transmission line carrying power from the source to the aerial takes the form of a waveguide, (as this introduces less losses and enables propagation to proceed more freely) the latter will have to be dealt with, in detail. It would be more instructive if the relevant theory of waveguides and aerials is given first, paying special attention to slot aerials which will be treated from an 'Equivalent Dipole' point of view. Following this the experimental stages of our work will be explained in detail, stating our procedure as we go along.