Abbas Vosoogh

Corporate-Fed Planar 60 GHz Slot Array Made of Three Unconnected Metal Layers Using AMC pin surface for the Gap Waveguide

This letter presents the design of a high-efficiency corporate-fed 8 ×8-slot array antenna in the 60 GHz band. The antenna is built using three unconnected metal layers based on artificial magnetic conductor (AMC) in gap waveguide technology. A 2 ×2 cavity-backed slot subarray is designed in a groove gap waveguide cavity. The cavity is fed through a coupling slot from a ridge gap waveguide corporate-feed network in the lower layer. The subarray is numerically optimized in an infinite array environment. The corporate-feed network is realized by a texture of pins and a guiding ridge. There is very good agreement between simulated and measured results. The fabricated antenna shows a relative bandwidth of 14% with input reflection coefficient better than -10 dB and an overall aperture efficiency larger than 65% (i.e., -2 dB) with about 25 dBi realized gain between 56.2 and 65.0 GHz.

Design and Validation of Microstrip Gap Waveguides and Their Transitions to Rectangular Waveguide, for Millimeter-Wave Applications

The paper describes the design methodology, experimental validation, and practical considerations of two millimeter-wave wideband vertical transitions from two gap waveguide versions (inverted microstrip gap waveguide, and microstrip packaged by using gap waveguide) to standard WR-15 rectangular waveguide. The experimental results show S11 smaller than -10 dB over relative bandwidths larger than 25% and 26.6% when Rogers RO3003 and RO4003 materials are used, respectively. The vertical transition from standard microstrip line packaged by a lid of pins to WR-15 shows measured return loss better than 15 dB over 13.8% relative bandwidth. The new transitions can be used as interfaces between gap waveguide feed networks for 60-GHz antenna systems, testing equipment (like vector network analyzers), and components with WR-15 ports, such as transmitting-receiving amplifiers. Moreover, the paper documents the losses of different gap waveguide prototypes compared with unpackaged microstrip line and substrate integrated waveguide (SIW). This investigation shows that in V-band, the lowest losses are achieved with inverted microstrip gap waveguide.

Fundamental Directivity Limitations of Dense Array Antennas: A Numerical Study Using Hannan’s Embedded Element Efficiency

Hannan introduced in 1964 an embedded element efficiency concept that explains the so-called element-gain paradox in antenna arrays, i.e., that the array gain always is smaller than the sum of the element gains. In the present letter, we show for the first time the usefulness of his approach by evaluating directivities and aperture efficiencies of an array of open-ended waveguides by commercial full-wave electromagnetic (EM) solvers for a large range of element spacing. The results show also that by using embedded element analysis, the realized gain of regular arrays actually becomes equal to the sum of the realized gains of the embedded elements. Thus, the embedded element efficiency is more practical to use in design and numerical analysis than the more commonly used active element pattern approach. We also show that the embedded element efficiency can be approximated by a simple formula when the element spacing is smaller than half-wavelength.

Design of integrated diplexer-power divider

A new configuration is introduced to integrate diplexers and power dividers. The proposed configuration is based on coupling matrix. The design of the lumped element network is based on addition of an extra term to the conventional error function of the coupling matrix to decouple the two ports of the power divider. An optimized lumped element network is implemented successfully on an EBG based guiding technology known as ridge gap waveguide. The optimization of the physical structure is done efficiently by dividing the diplexer-power divider into many sub-circuits and analyzing the corrected delay response of them.

Simple Formula for Aperture Efficiency Reduction Due to Grating Lobes in Planar Phased Arrays

This paper numerically validates a simple formula to calculate the aperture efficiency reduction due to grating lobes in planar phased arrays. Array antennas with element spacing greater than one wavelength will produce grating lobes. Grating lobes are not a big problem in most new millimeter-wave applications, except for the fact that they reduce the aperture efficiency and thereby normally the directivity. When the element pattern is known, the simple formula can be used to calculate the aperture efficiency in the presence of grating lobes. The formula is verified by the simulations of a large uniformly excited planar slot array. The agreement is good for both broadside radiation and a phased main beam, even if we use the far field of an isolated slot. Using the far field of the embedded slot element gives almost the same results, except when a grating lobe radiates along the ground plane and the isolated element pattern is nonzero in this direction.

An Integrated Ka-Band Diplexer-Antenna Array Module Based on Gap Waveguide Technology With Simple Mechanical Assembly and No Electrical Contact Requirements

This paper presents the integration of a diplexer with a corporate feed network of a high gain slot array antenna at the Ka-band. A hybrid diplexer-splitter with a novel architecture is proposed to have compatibility for its direct integration with the feed network of the array antenna. A seventh-order hybrid diplexer-splitter is successfully integrated into a corporate feed network of a

Slot antenna array unit cell directly fed by inverted microstrip gap waveguide

16\times 16

An E-band antenna-diplexer compact integrated solution based on gap waveguide technology

slot array antenna. The proposed integrated diplexer-antenna module consists of three distinct metal layers without the need of electrical contacts between the different layers based on the recently introduced gap waveguide technology. The designed module has two channels of 650-MHz bandwidths each with center frequencies 28.21 and 29.21 GHz. The fabricated prototype provides good radiation and input impedance characteristics. The measured input reflection coefficients for both Tx/Rx ports are better than −13 dB with the measured antenna efficiency better than 60% in the designed passband, which includes the losses in the diplexer.

Diplexer integration into a Ka-band high-gain gap waveguide corporate-fed slot array antenna

Inverted microstrip gap waveguide is mechanically flexible millimeter wave transmission line. This paper describes a single-layer slot antenna array unit cell at 60-GHz designed by using this inverted microstrip gap waveguide technology. This antenna unit mainly consists of a 2×2 slot layer and corporate-feed networks. The unit-cell shows more than 14.6% bandwidth over 57–66 GHz band with 10-dB return loss. Infinite array environment has been utilized later to determine overall efficiency for bigger 16×16 antenna array which is around 70% with a directivity value of 33.5 dBi between 57–66 GHz.

V-band high efficiency corporate-fed 8×8 slot array antenna with ETSI class II radiation pattern based on gap technology

In this paper, a novel compact integrated antenna-diplexer for Frequency-division duplex low latency wireless backhaul links at E-band is presented. The proposed solution is designed in a multilayer architecture with each layer having different functional blocks. The layers have been stacked on top of each other without any electrical contact requirement between them. This is achieved by using packaging property of gap waveguide technology. A corporate-fed 16 × 16 slot array antenna is integrated with a 5th order diplexer. The simulated reflection coefficients are better than −13 dB for both input ports in the designed passbands. The simulated realized gains at the middle of channel 1 (73.5 GHz) and channel 2 (83.5 GHz) are respectively 31.8 dBi and 32.9 dBi, obtaining a high isolation of 50 dB between the two input ports.