Wideband reflectarray antenna using logarithmic patch element

A wideband microstrip reflectarray antenna (RA) is proposed using a novel unit‐cell for X‐band applications. The unit‐cell is composed of a logarithmic toothed microstrip element and two‐variable phase‐delay lines (PDLs) for the required phase compensation in the RA. By adjusting the lengths of the PDLs, a smooth and almost linear phase variations of 627° is achieved at the frequency of 10 GHz. Based on the proposed element, a 144‐element center‐fed RA with dimensions of 216 mm × 216 mm is designed at 10 GHz and simulated using CST software. Then, a fabricated prototype RA is tested to validate the design approach. The maximum measured gain is 25.3 dB at 10.4 GHz, whereas the gain is 24.6 dB with 44.2% aperture efficiency at the design frequency of 10 GHz. Also, the measured gain frequency characteristic shows the 1 and 3‐dB gain bandwidths of 24.8% and 42.3%, respectively, and the measured radiation patterns verify the simulated ones as well.