Two-mirror cylindrical antenna system with high efficiency.

A technique for the synthesis of two-mirror cylindrical antenna systems for a given amplitude distribution in the aperture has been developed. At the first stage geometrical-optical synthesis is carried out, at the second stage a refined solution is found using the field of the feed on the secondary mirror found by the numerical method of finite element. As an example, a two-mirror cylindrical antenna system with a horn-lens feed and a uniform field distribution in the main mirror aperture has been synthesized. Using full-wave simulation by the finite element method, the analysis of the radiation characteristics of a synthesized two-mirror antenna system is carried out. The scanning characteristics of the antenna system by turning the main mirror are investigated. The efficiency of a cylindrical two-mirror antenna system with a horn-lens waveguide transition in the E-plane and an H- sectorial horn feed reaches 0.95 i.e. is close to the limiting value. When scanning the main lobe of the pattern in an angular sector of 27 degrees due to the rotation of the main mirror gain exceeds 26 dB, and efficiency exceeds 0.8.

Experimental Characterization of 2 × 2 Electronically Reconfigurable 1 Bit Unit Cells for a Beamforming Transmitarray at X Band

This paper proposes a reconfigurable unit cell for a transmitarray operating at the X band. The unit cell consists of an active patch, a passive patch, and a phase shifter. The active patch has two PIN diodes that change the phase of 180° of the transmitted waves. The passive and active patches both have circular slots to enhance the bandwidth of the transmitted wave. We also propose a new type of experimental characterization technique to measure the performance of the unit cells at the X band without fabricating the entire transmitarray. Instead of a 1 unit cell as described in the literature, we propose 2 × 2 unit cells to measure the performance of unit cells using the X band waveguide. The waveguide consists of a WR-90 section and a rectangular to square waveguide transition section that can be fit to our proposed structure. A good agreement between simulated and measured results was found.