Grating lobe suppression in phased arrays composed of identical or similar subarrays
The grating lobe suppression methods for non-equidistant array antennas composed of identical or similar subarrays are proposed. Subarrays have equidistant rectangular or triangular grid. The grating lobes of an antenna array are reduced due to the irregular arrangement of subarrays. The following methods are considered: relative shift of neighbor subarrays, arranging gaps between subarrays, using different element spacing in different subarrays, rotation of subarrays, and combination of these methods. The methods provide suppression of the grating lobes from −2.6 dB to −11 dB as compared to equidistant arrays while side lobes envelop grows slightly.
Grating lobe suppression in rotationally tilec arrays
Uniform placement of array elements limits its maximum frequency due to the formation of grating lobes. While non-uniform element or subarray spacing have significantly lower grating lobes, it reduces aperture efficiency and leads to arrays that are difficult to design and manufacture. We propose a modular asymmetric convex-shaped subarray to construct the array by rotation and translation, filling the aperture without overlaps or gaps. This new approach can achieve lower grating lobes compared to uniform array geometries. It can also lower design, manufacturing and operation costs by offering interoperable subarrays and provide array size flexibility.
Numerical solution of waveguide-discontinuity problems
A method for the solution of waveguide-discontinuity problems using a digital computer is described, and examples are given to illustrate possible applications. For the method to be applied, the discontinuity must lie entirely in a surface transverse to the direction of propagation, and various techniques are described for treating planar discontinuities. Examples include a change in waveguide cross-section and a change in the cross-section of a dielectric contained within a uniform waveguide. Favourable comparison is made with experimental results and alternative theoretical results, where these are available. Virtues of the method are simplicity and the ease with which discontinuity problems in overmoded waveguides may be treated.