Monopulse wideband waveguide based travelling wave array antenna

Gültepe, Gökhan
A novel, travelling-wave, waveguide-based antenna array structure with dual-plane monopulse capability is developed. It is an end-fed, broad wall longitudinal slotted, ridged waveguide-based printed antenna array. Even if the structure is scalable, it is designed to operate in S-band. The structure consists of printed antennas on two interleaved waveguide arrays whose dimensions are shrinked to make interleaving operation possible to keep inter-element spacings the same in both the azimuth and elevation planes. The inherently wideband printed antennas, linearly tapered slot antennas (LTSA), are excited via probes inserted into the waveguides to control the amplitude of the radiated E-field to generate desired sum and difference patterns. These LTSAs are expected to eliminate the narrow frequency characteristics of the slots on waveguides, and to improve the bandwidth. Besides, the unit cell of the array is modelled as 5-port networks to handle the couplings between array elements by using their scattering parameters. The array with desired radiation patterns is generated by a code implementation, which chooses the preoptimized array elements with proper radiation control parameters in MATLABTM. Also, a method to improve radiation patterns is presented to ease the coupling related degredations in the radiation patterns. Finally, a 30-element monopulse array with 25 dB Taylor and Taylor-like difference distributions is generated in MATLABTM, simulated in HFSSTM, and manufactured. The manufactured array is measured in planar near-field measurement setup, and the measurement results are verified after the comparison with the simulated ones.