A new configuration of printed non-directive surface-wave sources for advanced beam control

Abstract

An array of surface-wave launcher (SWL) sources is presented for surface-wave (SW) control and beam steering on a grounded dielectric slab (GDS). Specifically, a four element array configuration of non-directive SWLs is investigated. By varying the relative phase difference and magnitude between SWL elements, the excited SW field distribution on the guiding surface can be steered and controlled. Simulations and measurements of a single SWL element are provided along with simulations of the proposed array. If metallic gratings or strips, or additional dielectric layers are placed on top of the GDS, the bound SWs can be transformed into radiated leaky-waves (LWs) and directive beam patterns can be generated in the far field. Examples are provided illustrating that broadside beam steering and circular polarization can be achieved at a single frequency. These slotted SWL arrays can be useful for novel SW beam scanning designs and other LW or cavity based antennas.

Design of a Polarization-Diverse Planar Leaky-Wave Antenna for Broadside Radiation

“…The SWLs considered here represent an arrangement of magnetic dipole sources on the ground of a GDS made with a high value for the relative dielectric constant (ε r > 10), and by substrates having thickness according to h √ ε r /λ 0 ≈ 1/4 [31], they excite a bound TM 0 mode whilst operating above the TE 1 mode cutoff frequency. Typically, under these conditions more than 80% of the input power can be coupled into the dominant TM 0 SW mode of the slab for radiation [27], [31]. Our reported array-fed, 2-D planar, LWA design is illustrated in Fig.…”

“…An attractive simple and low-cost solution to synthesize high-gain LP and CP beams as well as monopulse patterns, with the same antenna structure, can be made possible by array-fed 2-D LWAs. This is proposed here through the excitation of a fast space harmonic [11], achieved by periodically perturbing the fundamental surface wave (SW) supported by a grounded dielectric slab (GDS), and feeding the antenna by introducing a small number of fully-integrated phased sources, while expanding on the originally studied in [27], [28], and [29] which mainly investigated singlefrequency beam steering at broadside.…”

“…When considering relatively high-dielectric constant values, efficient TM SW excitation has been shown by means of planar surface-wave launchers (SWLs) [34], [35]. In particular, this SW source can act as a printed magnetic dipole element and both directive and non-directive SWLs have been proposed for the realization of unidirectional and bi-directional TM SW field distributions [31], [36], [37], with an original 2 × 2 SWL array reported in [27].…”

“…To achieve such a polarization reconfigurability of the far-field beam pattern, we propose the design of an annular bull-eye LWA fed by non-directive SWLs whilst considering 50-coplanar waveguide transmission-line connectivity [31], [37]. More specifically, we report the complete findings of an original 2 × 2 square arrangement of nondirective SWLs [27] positioned at the origin of the ground plane (see Fig. 1) with LW radiation by the printed MSG on the top air-dielectric interface of the employed GDS.…”

Analysis and design of new electronically reconfigurable periodic leaky-wave antennas

“…[Chang 2012] proposed a LWA with capability for multi-plane scanning. In [Podilchak 2010] a pattern-reconfigurable two-dimensional LWA is considered built from a grounded dielectric substrate loaded with an annular bull-eye grating and excited by an array of four surface wave launchers (SWL). Controlling the amplitude and phase difference of the SWL array, it was demonstrated that beam-steering could be achieved at different azimuth planes, besides broadside radiation.…”