No abstract

A broadband single-layer reflectarray antenna comprising circular ring elements dented with sectorial slits is presented. The sizes of circular rings are fixed and equal for all elements, while the variation of the reflected phase is obtained by varying the lengths of the sectorial slits dented within the circular rings. In this arrangement, the rapid geometric variations among the neighboring elements encountered in conventional reflectarray antennas can be prevented. The proposed element can yield a linear reflected phase together with a high reflected magnitude and important geometric parameters are examined to gain an insight into its broadband operation. Using the proposed unit cells, a 25 • offset-fed reflectarray containing 529 elements with a grid periodicity of 0.3λ at 10 GHz, is designed, built, and tested. Experimental results indicate that the designed reflectarray antenna can realize a broad 30% 1-dB gain bandwidth with a 58.3% aperture efficiency. In addition, good sidelobe and cross-polarization levels in the ranges of 17.5 dB and 32 dB are also achieved at 10 GHz.

No abstract

A wideband reflectarray antenna consisting of single‐layer dipole element attached with T‐shaped stubs is proposed. By varying the lengths of the T‐shaped stubs, the unit cell can provide a linear phase curve covering about 420°. Critical design parameters are analyzed to understand its wideband operating mechanism. Using this novel type of unit cells, a 441 element 25° offset‐fed reflectarray with grid spacing of λ/3 at 10 GHz is designed, fabricated, and measured. The experimental results show that the proposed reflectarray can achieve 1‐dB gain bandwidth of 24% and 1.5‐dB gain bandwidth of 37%. In addition, aperture efficiency of 66.6% and cross polarization level of 29 dB are obtained at 10 GHz, respectively.

In this paper, a simple high-selectivity wideband bandpass filter based on a novel π-shaped coupled-line structure is introduced. The presented filter realizes wide bandwidth, excellent passband selectivity and good stopband suppression by using two coupled lines with diagonal open-circuited ports and three coupled lines with cascaded ports. The design theoretical analysis and the complete equation derivation are provided in detail. Furthermore, a prototype with 3-dB fractional bandwidth of 50.9% is simulated, fabricated, and measured. The simulated and measured results have a good consistency, which verifies the analytical design principle.