A Wideband Reconfigurable Dual-Branch Helical Reflectarray Antenna for High-Power Microwave Applications

A wideband high-power dual-branch helical reflectarray antenna (RAA) is presented. The reflecting element consists of two metal helical branches, and the variable rotation angles enable full 360 degrees phase adjustment. An X-band RAA prototype with 9 x 9 rectangular grid is simulated and measured. Full-wave simulations show that the maximum gain of 23.7 dB is achieved with the beam focused at (theta = 20 degrees, phi = 0 degrees) direction at center frequency of 9.3 GHz and the 1 dB gain bandwidth is over 24.2%. The measured reflection coefficient is lower than -16.3 dB in the whole band. From 8.4 to 10.8 GHz, the tested axial ratio is less than 2.3 dB. At center frequency, the tested gain is 23.4 dB and the corresponding aperture efficiency is 50.6%. The beam-scanning performance of the RAA is tested within 30 degrees angular in two orthogonal planes with the scan loss of less than 1.5 dB and the axial ratios of lower than 1.4 dB. Taking the flat-topped beam as an example, the beam-forming capability of the RAA is verified. The measured results demonstrate the feasibility of the proposed design. The simulated results show that the power-handling capacity of the RAA is about 358 MW under vacuum condition.