Wide-band Beam-scanning by Surface Wave Confinement on Leaky Wave Holograms

Abstract

A two-dimensional (2-D) metasurface design for backward leaky wave suppression in microwave regime is proposed based on the theory of holography. The so-called Rabbit’s ears phenomenon describes that the backward mode in the reference wave plays the destructive role and makes the holography principle to behave properly mainly in an only narrow frequency interval. Here, we explore the utilization of the surface wave reflectors to suppress the backward mode to achieve wide-band holograms. Therefore, the reference wave form is manipulated by the choice of various reflector shapes and some providing forward mode dominant reference wave are analyzed and simulated. The less backward mode participates in the reference wave; the wider operation frequency range is obtained. With the canceled Rabbit’s ears phenomenon, variations in the reference wave frequency cause elevation angle scan. The results provide general insights into relation of the Rabbit’s ears phenomenon and the object wave accuracy in frequencies except the design frequency. The idea is also applied to multiple object wave holograms. The concept is verified using both electromagnetic full-wave simulations and experimental measurements.

Electromagnetic Metamaterials: A New Paradigm of Antenna Design

“…The amplitude and propagation direction of electromagnetic waves is controlled by leaky waves. The important property of metasurface allows manipulating surface wave leakage that results in improving the performance of the antenna [118]. In [119] designed a microstrip antenna based on the photonic crystal on the FR4 substrate having a gain of 5.93 dB, directivity of 6.92 dB, and maximum fraction bandwidth of 7.86%.…”

Temporally Modulated One-Dimensional Leaky-Wave Holograms

“…As discussed in the previous section, The infinite system of equations in (25) should be solved for the determination of the exact values of eigenstates in the presence of space-time modulation, which is achieved by safely truncating the number of modes without generating of a significant error. In reference 40 it has been shown that considering only three Floquet modes (namely n = 0, ±1) results in sufficiently accurate solutions.…”

“…An appropriate approach to implement spatio-temporally modulated structures is to use dynamic metasurfaces, which have several advantages such as ultra-thin thicknesses, low cost and high flexibility. Metasurfaces are mainly exploited in transmissive [14][15][16][17][18][19] , reflective [20][21][22][23] , or leaky-wave 24,25 modes. The main drawback of microwave metareflectors and transmitarrays is their protruded feeds which make them unsuitable for low-profile integrated systems.…”

A circularly polarized, high aperture efficiency metasurface antenna

“…In microwave frequencies, MTSes are fabricated by pattering the electrically small resonators on a printed circuit board (PCB) laminate (with a negligible thickness with respect to the wavelength). By utilizing MTSes, low‐profile, light weight and low cost antennas with enhanced functionality such as high gain, improved bandwidth, and multi beam have been achieved 20–24 . The application of MTSes has also been extended to design CP antennas 25–39 .…”