Analysis and Design of Reflectarray Antennas Based on Delay Lines: A Filter Perspective

Abstract

The analysis and design of reflectarray (RA) antennas based in delay lines is introduced for the first time from a filter perspective. To this purpose, each unit-cell of the RA is considered as a network composed of two ports, one being the delay line and the other one the free-space. This approach allows to borrow the coupling matrix formalism from filter theory and apply it to design unit-cells exhibiting broadband operation together with very sharp frequency responses. The concept is demonstrated with the aid of planar printed unit-cells coupled to substrate integrated waveguides (SIWs) through slots, a configuration that offers significant advantages to shape its frequency response while providing relatively low loss. With the aim of validation, a third order filter structure integrated in SIW-based unit-cells has been experimentally tested using the waveguide simulator technique, at a center frequency of 9 GHz. Measurements demonstrate a high-quality linear phase variation and range, and large frequency selectivity together with broadband response for the element of about 18%. The experimental results show the feasibility of this approach for the design of broadband reflectarray antennas exhibiting sharp gain responses. To illustrate the concept, a medium size reflectarray has been theoretically designed using the proposed unit cell at 9 GHz, showing a directive beam with 35.8 dB gain, sharp gain selectivity over 18 dB, and confirms the wide band operation with 20.3% bandwidth for a 3 dB gain variation. INDEX TERMS Broadband antennas, delay-line elements, filter theory, gain selectivity, reflectarray antennas, substrate integrated waveguide.

W‐band large‐scale high‐gain filtering reflectarray antenna

“…The theory behind realizing the filtering functionality was thoroughly explained from filter perspective in our previous work. 16 The proposed element is seen as a second-order filter, composed of a resonant slot and a resonant patch, which is a tri-section topology. When the incidence wave at in-band frequencies illuminate the patch, the wave is coupled into the SIW through the slot and it propagates in forward direction.…”

“…The theory behind realizing the filtering functionality was thoroughly explained from filter perspective in our previous work 16 . The proposed element is seen as a second‐order filter, composed of a resonant slot and a resonant patch, which is a tri‐section topology.…”

Time-modulated Patch Antennas with Tunable and Nonreciprocal Polarization Ellipticity

“…In this 3D simulation, the antenna is placed in a periodic environment using two Floquet ports associated to the fundamental TE and TM modes at the broadside direction. This approach permits to obtain the amplitude and phase of the fields radiated by antenna, as detailed elsewhere [47]. Even though this simulation accounts for an infinite two-dimensional array of patch antennas, the dimensions of the unit-cells ensure a negligible cross-coupling at the targeted broadside direction.…”

A novel Ku/K band reflectarray antenna with reduced phase slope and phase sensitivity

“…A gain selectivity of 6 dB is obtained at the lower cut‐off frequency. This value can be increased at both upper and lower cut‐off frequencies if changes in the variation of the elements over the array are made differently 28 . In such a case the proposed antenna can be modified as a filtenna.…”