Broadband Low-cost Reflectarray based on a New Phase Synthesis Technique and a Class of Cross Bow-Tie Cells

Abstract

In this paper, a class of Bow-tie unit cell on FR4 substrate is designed and investigated to be used in implementing a single-layer broadband Reflectarray Antenna (RA). In the analyzing step, two different parameters (length and angle) of the grounded Cross Bow-Tie (CBT) are varied to obtain the phase diagrams. Various degrees of freedom in the CBT structure are very helpful in designing a broadband RA. In the antenna design procedure, an efficient phase synthesis technique is applied to minimize the adverse effects of frequency dispersion causing by the differential space phase delay at different frequencies. This technique optimizes the metallic CBTs arrangement on the aperture of RA, and reduces the dependency of RA design to the CBT’s phase variation. Consequently, combination of the CBT’s phase behavior and the phase synthesis technique leads to designing a broadband RA with a good frequency response. In addition to, the Side Lobe Level (SLL) of the resultant RA is reduced remarkably. For validation of the obtained numerical results, an RA is designed and fabricated in 8.7~12.3GHz frequency bandwidth. The measurements show 27.03 dB as a maximum gain value at 10.2 GHz with a 1.5dB gain bandwidth of 34%. It is also shown that the implemented RA exhibits a reduced SLL (<-18dBi) within its operating bandwidth.