Single-Layer Dual-Band Wide Band-Ratio Reflectarray With Orthogonal Linear Polarization

In this letter, a single-layer broadband wide band-ratio (ratio of
$f_{higher} $
to
$f_{lower} $
) reflectarray that can achieve different linear polarizations at the X-band and the K-band is designed. Its elements consist of a split square loop with two square shaped phase delay lines (outer structure) and a phoenix square loop (inner structure) operating at the X-band and the K-band, respectively. The ingeniousness of the design is that the outer structure and the inner structure can achieve a 0° – 360° phase shift by adjusting the phase shift lines and the side length of the inner square ring, respectively. At the same time, they do not affect each other in space. Different polarizations corresponding to the two structures are orthogonal to each other, so their electrical performances do not affect each other. To verify our design concept, the reflectarray is fabricated and measured in a microwave anechoic chamber. The simulated and measured results are in good agreement. The measured gains are 23.6 dBi at 10 GHz (
$f_{lower}$
) with aperture efficiency of 48%, and 30.6 dBi at 22 GHz(
$f_{higher}$
) with aperture efficiency of 43%. The 1-dB gain bandwidths are 20% (9.1 GHz–11.1 GHz) at the X-band and 19% (19.8 GHz–23.9 GHz) at the K-band. The band-ratio of the reflectarray is 2.2. A single-layer dual-band wide band-ratio reflectarray with dual-linear polarization is confirmed.