A two‐layer beam‐steering array antenna with 4 × 4 modified Butler matrix fed network for switched beam application

This paper presents a novel two layers beam‐steering array antenna fed by a 4 × 4 modified Butler matrix. Each of the radiation elements have been replaced by a collection of 2 × 2 circularly polarized (CP) square patches, which joined together by a modified sequentially rotated feed network. The antenna array consists of 2 × 5 CP square patches, which connected to four ring sequential rotation and fed by butler matrix. The proposed Butler matrix which plays a role as beam‐steering feed network consists of four novel 90° circular patch couplers and two 45° half circular patch phase shifter. Altogether, using of a 2 × 5 phased array antenna and a modified Butler matrix cause to empower array antenna for covering frequency range between 4.67 to 6.09GHz, the maximum gain of 14.98 dB and 3‐dB axial ratio bandwidth of 1.2GHz (4.9~6.1GHz) is attained.     

A triple‐slotted substrate integrated cavity‐fed 2 × 2 metasurface antenna with wide bandwidth

This article presents a triple‐slotted substrate integrated cavity (SIC)‐fed 2 × 2 metasurface antenna. Three modes can be obtained including TM₁₀ mode of the metasurface, TE₂₁₀, mode and TE₃₁₀ mode of the SIC. The TE₂₁₀ mode of SIC radiates through the two side slots and is coupled to the metasurface mainly by the two side slots, while the TE₃₁₀ mode of SIC is mainly coupled to the metasurface by the middle slot. Comparing with the reported SIC‐backed slot antenna, dual‐slotted SIC‐fed patch antenna or the metasurface antenna, the proposed antenna exhibits the advantage of wide bandwidth with flat gain. One prototype operated at 10 GHz was fabricated and measured with 10‐dB fractional bandwidth of 33%, the gain of 8.1 dBi at the center frequency, the cross polarization level of 20 dB and the gain ripple of 1.5 dB.     

Compact 2 × 2/4 × 4 tapered microstrip feed MIMO antenna configuration for high‐speed wireless applications with band stop filters

In this research, compact tapered feed 2 × 2/4 × 4 MIMO antenna are presented and investigated. The proposed MIMO antenna consists of a square patch and modified rectangular ground, which is chamfered at edges and etched with two semicircular slots. Likewise, obstruction caused by WiMAX and WLAN interfering bands is also taken care of by introducing notched filters. WiMAX is removed by embedding an rotated T‐type stub and a C‐type slot eliminates the WLAN band. The proposed antenna configuration covers the usable bandwidth of 3.07 to 11.25 GHz for 2 × 2 MIMO and 2.97 to 11.28 GHz for 4 × 4 MIMO. Also, both the MIMO antennas provide isolation <–20 dB. Proposed MIMO antennas are fabricated and characterized in near, far‐field, and diversity performance where envelope correlation coefficient, directive gain (DG), total active reflection coefficient (TARC), and channel capacity loss are simulated and measured. 4 × 4 MIMO antenna configuration provides stable gain with a maximum radiation efficiency of 91% and monopole radiation patterns.     

A 2 × 2 array antenna with circular polarization and conical beam radiation

A circular disk patch antenna loaded with a hemi‐circular slot is initially proposed for achieving circular polarization (CP). To exhibit broad CP bandwidth that can cover the WLAN 2.4 GHz operating band, the patch antenna is fed by an L‐shaped probe. To further attain conical beam radiation with peak gain of ～8 dBic at ±30 degrees theta angle (θ), a 2 × 2 array type is proposed in this study, in which four circular disk patch array elements are arranged in a sequentially rotated fashion via a corporate feed network. Here, desirable 3‐dB axial ratio (AR) bandwidth and 10‐dB impedance bandwidth of ～5% and 21% were measured. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:223–228, 2014.     

360°‐viewable cylindrical integral imaging system using a 3‐D/2‐D switchable and flexible backlight

Abstract— A 360°‐viewable cylindrical three‐dimensional (3‐D) display system based on integral imaging has been implemented. The proposed system is composed of a cylindrically arranged electroluminescent (EL) pinhole film, an EL film backlight, a barrier structure, and a transmission‐type flexible display panel. The cylindrically arranged point‐light‐source array, which is generated by the EL pinhole film reconstructs 360°‐viewable virtual 3‐D images at the center of the cylinder. In addition, the proposed system provides 3‐D/2‐D convertibility using the switching of EL pinhole film from a point light source to a surface light source. In this paper, the principle of operation, analysis of the viewing parameters, and the experimental results are presented.     

A compact proximity‐fed 2.4 GHz monostatic antenna with wide‐band SIC characteristics for in‐band full duplex applications

This article presents a dual polarized, proximity‐fed monostatic patch antenna (single radiator for both transmit and receive modes) with improved interport isolation for 2.4 GHz in‐band full duplex (IBFD) applications. The proximity‐fed radiating patch offers comparatively wider impedance bandwidth for presented design. Very nice self‐interference cancelation (SIC) levels for intended impedance bandwidth have been achieved through differential receive (R_x) mode configuration. The differential R_x mode based on 180° ring hybrid coupler acts as a signal inversion mechanism for effective suppression or cancelation of in‐band self‐interference (SI) that is, the leakage from transmit port. The implemented prototype of proposed antenna achieves ≥87 dB peak isolation for dual polarized IBFD operation. Moreover, the recorded interport isolation for validation model ≥60 dB within 10 dB‐return loss bandwidth of 90 MHz (2.36‐2.45 GHz). The measured radiation characteristics of implemented antenna demonstrate nice gain and low cross‐polarization levels for both transmit (T_x) and receive (R_x) modes. The dimensions of implemented antenna are 70 × 75 × 4.8 mm³. The novelty of this work is wide‐band SIC performance for monostatic antenna configuration with compact structure of presented design.     

Design and evaluation of a vertically integrated passive two‐dimensional beam switching antenna array at 60 GHz

A millimeter‐wave two‐dimensional (2D) beam switching planar microstrip patch antenna array excited by a 4 × 4 substrate‐integrated waveguide Butler matrix (BM) is presented in this article. The BM architecture is modified to feed the planar array in a vertically integrated multilayer design to minimize parasitic effects due to junction discontinuity and reduce the radio frequency (RF) front‐end footprint. This feed architecture enables the designer to control the phased array inputs to achieve a set of beam directions in four quadrants of radiation space at a desired elevation angle. For verification of beam switching via over‐the‐air measurements at 60 GHz, a bench‐top anechoic chamber with proper transmitter and receiver antenna positioners was designed and fabricated using in‐house laboratory resources. 2D beam steering was confirmed in the intended four quadrants of radiation space at ?₀ = 50°, 140°, 220°, and 300° and θ₀ = 30° ± 5°, meeting the design specifications with a very good margin. Each switched beam demonstrated between 5 and 6 dBi gain at 60 GHz, which is within 1 dB deviation from the simulated results.     

Depth‐ and viewing‐angle‐enhanced 3‐D/2‐D switchable display system with high contrast ratio using multiple display devices and a lens array

Abstract— An improved 3‐D/2‐D switchable display system with enhanced depth and viewing angle by adding two LCD panels to an integral imaging system has been realized. The proposed system uses the see‐through property of an LCD panel and displays multiple sets of elemental images on the LCD panels to integrate them on multiple locations simultaneously. As a result, the depth of the 3‐D image can be enhanced. For wide viewing angles, the time‐multiplexing method was adopted by displaying mask patterns on the front LCD panel. In addition, another technique to increase the contrast ratio of the proposed system has also been developed. Some experimental results will be provided.     

Development of “H‐Shaped” monopole antenna for IEEE 802.11a and HIPERLAN 2 applications in the laptop computer

A very low profile and ultra‐thin “H‐Shaped” antenna for IEEE 802.11a and HIPERLAN 2 wireless applications in the laptop computer is developed. The antenna is designed using only a pure copper strip of size 17.5(L) × 4(W) mm² with thickness of only 0.035 mm. The novelty of the proposed antenna is that the antenna is designed with only one rectangular radiating strip without using any additional reactive components, vias or three dimensional structure. Furthermore, the proposed antenna does not require any additional ground plane for installing in laptops. The proposed antenna is comprised of one radiating strip, one rectangular stub, and two resonating slots, namely, “X” and “Y” of length 7.5 mm and 7 mm, respectively. The proposed structure resonates at around 5.5 GHz can cover the (5.15‐5.35/5.725‐5.825) GHz IEEE 802.11a and (5.15‐5.35/5.470‐5.725/5.725‐5.925) GHz HIPERLAN 2 bands. The fabricated prototype antenna has measured impedance bandwidth (VSWR<2) of 15% (5.10‐5.92 GHz) across the operating bands. The measured radiation patterns are nearly omnidirectional along with stable gain of 5 dBi. Moreover, the proposed antenna exhibits excellent radiation efficiency of around 90% across the operating bands. The simulated and measured results of antenna are found to be in good agreement. The very low profile and ultra‐thin structure make it an excellent candidate for wireless operations in the ultra‐thin laptop computers.