Reconfigurable nested ring-split ring transmitarray unit cell employing the element rotation method by microfluidics

A continuously tunable, circularly polarized X-band microfluidic transmitarray unit cell employing the element rotation method is designed and fabricated. The unit cell comprises a double layer nested ring-split ring structure realized as microfluidic channels embedded in Polydimethylsiloxane (PDMS) using soft lithography techniques. Conductive regions of the rings are formed by injecting a liquid metal (an alloy of Ga, In, and Sn), whereas the split region is air. Movement of the liquid metal together with the split around the ring provides 360° linear phase shift range in the transmitted field through the unit cell. A circularly polarized unit cell is designed to operate at 8.8 GHz, satisfying the necessary phase shifting conditions provided by the element rotation method. Unit cell prototypes are fabricated and the proposed concept is verified by the measurements using waveguide simulator method, within the frequency range of 8-10 GHz. The agreement between the simulation and measurement results is satisfactory, illustrating the viability of the approach to be used in reconfigurable antennas and antenna arrays. © 2015 IEEE

Efficient analysis of large finite arrays via mom formulation with dft based acceleration algorithms

A DFT based acceleration algorithm is combined with iterative methods to accelerate the computation of Method of Moments (MoM) analysis of electromagnetic radiation/scattering from large, finite free-standing and printed elements of phased arrays. Computational complexity of this approach is O(Ntot), where Ntot is the number of unknowns. Numerical results are presented to validate the efficiency and accuracy of the method

Proof of concept of a dual-band circularly-polarized RF MEMS beam-switching reflectarray

In this communication we propose the concept of a circularly polarized reflectarray (RA) antenna capable of independent beam-switching in both K and Ka bands. The RA unit cell comprises one microstrip ring per each operation frequency. Each ring is integrated with six equally spaced series RF micro electro-mechanical systems (RF MEMS) switches, which allows implementing the sequential rotation principle formerly used in circularly-polarized RA for single-frequency operation. A detailed design is proposed, considering the best relative arrangement of the rings corresponding to each frequency, the accurate modeling of the RF MEMS switches, and the full-wave simulation of the full array. The designed RA is implemented on a 4-inch quartz wafer and comprises 109 K-band and 124 Ka-band split-rings. Two prototypes representing two frozen states of the reconfigurable antenna are fabricated and measured. The designed RA can +/- 120 degrees provide progressive phase difference in both operation bands exhibiting beam switching to +/- 35 degrees and +/- 24 degrees off the broad-side in K and Ka bands respectively. The performance of the designed antenna is verified by the agreement of the measured and simulated radiation patterns