We investigate the aptness of various $4^{th}$ order (90°) rotationally symmetric phase-transforming cells for the upper phase-gradient metasurface, which always receives an oblique incidence wave from the lower metasurface in a Near-Field Meta-Steering system. A comprehensive study on the behavior of various phase-transforming cells and corresponding supercells when a rotating oblique plane wave impinges on them is presented. First, we select the supercell with high transmission in the desired output Floquet modes, for both TE and TM input modes, when an oblique incidence wave is rotated. The selected supercell is then optimized using Floquet analysis in conjunction with particle swarm optimization (PSO). All the undesired modes are successfully suppressed below −32 dB in the optimized supercell, and the predicted broadside radiation pattern is free of spurious grating lobes. A Near-Field Meta-Steering system with an aperture diameter of $7.3\lambda _{0}$ (110mm @ 20 GHz) is presented. It has a pair of optimized phase-gradient metasurfaces and a dipole antenna array. A maximum peak directivity of 24.2 dB is achieved when the beam is in the broadside direction. The proposed steering system is capable of scanning a conical range with an apex angle of 126° when a 6 dB reduction in peak directivity is allowed. For a 3 dB variation in the peak directivity, the corresponding apex angle is 103°.

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Designing Efficient Phase-Gradient Metasurfaces for Near-Field Meta-Steering Systems

In this paper, the interconnection/transition between two popular printed circuit board (PCB) technologies, i.e., the substrate integrated suspended line (SISL) and the air-filled substrate integrated waveguide (AFSIW), is studied and designed. To obtain a smooth wave propagation and mode transition between quasi-TEM to TE10, a novel compact transition structure is proposed and investigated. In addition, the fabrication tolerance is investigated through the multilayer misalignment analysis. To experimentally validate the circuit, two Ka -band back-to-back transitions, also known as the single-layer and double-layer structures, are designed for potential multifunction applications with enhanced power handling capability and fabricated only using the low-cost FR-4 substrate. The measurements show an operation bandwidth of 26.5–40 GHz/26.5–39 GHz, the insertion loss of 0.4–1.03 dB/0.5–1.27 dB, and the return loss of better than 13 dB/12 dB of the two back-to-back transitions.

Ka -Band SISL-to-AFSIW Transitions With Fabrication Tolerance Characteristics

A planar microwave crossover is presented. The structure uses a suspended substrate transmission line configuration to cross two independent RF channels. In the central crossed region, one channel is bridged by a conductor on the upper side of the substrate, while the second channel is bridged on the lower side. Two conductive stubs, realized as screws in the fabricated prototype, are placed on both sides of the crossed region to adjust the capacitance in this section and improve the impedance match of each channel. Measurements show that the overall bandwidth of the crossover with less than 0.5-dB insertion loss is from dc to 12 GHz (200% fractional bandwidth). Over this band, the measured return loss and isolation between the two channels are more than 15 and 17 dB, respectively.

Hyperwideband Microwave Crossover Using Bridged Suspended Substrate Line Configuration

The invention discloses an ultra-wideband coaxial line-equivalent stripline plane transition structure and belongs to the microwave field, in particular to the mobile communication field. The transition structure is applied to electromagnetic wave t ransmission of coaxial line-equivalent stripline and comprises a semi-open metal cavity and a top metal layer, a dielectric base layer, a bottom metallayer and a metallized through hole in the semi-open metal cavity. The dielectric base layer is located between the top metal layer and the bottom metal layer. As that design structure of the invention is simple, the process is easy, the working bandwidth meet the mobile communication frequency band, the excellent circuit matching between the coaxial line and the equivalent strip line circuit canbe realized, and the echo loss and the circuit los of the microwave component device based on the equivalent strip line are effectively reduced.

An ultra-wide band coaxial line-equivalent stripline plane transition structure

This paper presents a high rejection and compact ultra-wideband (UWB) highpass filter using suspended stripline technology based on Generalized Chebyshev polynomial that operates between 3 GHz to 12 GHz for wideband application. Based on the Generalized Chebyshev polynomial, a 13th order lowpass filter with 5 pairs of finite transmission zeros (TZ) is synthesized. Under frequency transmission, the highpass filter network can be realized. Suspended stripline is used to realize the proposed highpass filter by introducing parallel coupled line placed between the ultra-thin Roger Duriod RO3003 substrate and the resonators to obtain higher coupling and achieve very wideband. With the unique passband, stopband elements and excellent reliability in rough working condition, the application of the filter ranging from military and aerospace to commercial communication system such as ultra-broadband receiver, 5G and others. The proposed filter is simulated, fabricated, and tested to verify the proposed design concept. The measured and simulated results are in agreement to each other. Therefore, the highpass filter in this paper could serve as a reference for high rejection and ultra-wideband application.

High Rejection Highpass Filter for Wideband Applications Using Suspended Stripline Technology

A coaxial cable to suspended substrate (SS) transmission line transition is presented. The structure is simple to manufacture, consisting of two cascaded SS transmission lines and an orthogonal coaxial cable interface. Simulations show that the transition achieves more than 19 dB return loss and less than 0.1 dB insertion loss over 18–22 GHz (20% fractional bandwidth).

Orthogonal coaxial to suspended substrate transition for K band operation

A novel planar microwave crossover is presented that uses a suspended substrate configuration to cross two transmission channels. Conductive blocks placed on upper and lower sides of the crossed region guide the electric field due to each channel in opposing directions and therefore allow both channels to transmit with minimal interference. From DC to 18.4 GHz (200% fractional bandwidth), simulation results show more than 16.5 dB return loss, more than 14.4 dB isolation, and less than 0.5 dB insertion loss.

Wideband microwave crossover using suspended substrate transmission line configuration

A compact, flat beam steerable antenna is described. The antenna includes a waveguide for conveying electromagnetic energy and an adjustable moire pattern assembly disposed adjacent to the waveguide. The moire pattern assembly is arranged to present varying moire patterns comprised of regions of contrasting conductivity. In use, a direction for transmission of the electromagnetic radiation through the moire pattern assembly can be varied by operation of the assembly to alter the moire pattern.

A directional flat-panel antenna

This paper presents a novel reconfigurable SOTM antenna subsystem that possess a complete planar leaky-wave structure, low cost, and 2D-continuous beam steering. The proposed Ka-band antenna is developed from a Substrate Integrated Imaging Guide (SIIG) structure mounted on a conducting ground layer; a number of periodic copper strips are placed on the top surface of SIIG in order to perturb the surface wave and produce fast wave radiation. The mechanical movement of telescopic arm is able to tune the distance between each adjacent strips that leads to a steerable radiating pattern. The proposed antenna design is modelled and successfully verified by full-wave simulation software package.

John Ness

Papers

Hyperwideband Microwave Crossover Using Bridged Suspended Substrate Line Configuration

Orthogonal coaxial to suspended substrate transition for K band operation

Wideband microwave crossover using suspended substrate transmission line configuration

A directional flat-panel antenna

Low-cost Ka-band Reconfigurable Planar Antenna for Satellite-on-the-Move Application