Half-mode Cavity Research Articles

Ultra-miniaturized HMSIW cavity-backed reconfigurable antenna diplexer employing dielectric fluids with wide frequency tuning range.

This communication presents an ultra-miniaturized two-way frequency tunable antenna diplexer based on cavity-backed slots and dielectric fluids. The proposed antenna utilizes two half-mode substrate-integrated rectangular cavities loaded with slots and fluidic pockets. The conventional size reduction is achieved by employing half-mode cavities, whereas ultra-miniaturization is obtained by applying the slots, which provides additional capacitive loading. As the cavities are of unequal sizes, a weak cross-coupling path is created between the ports to obtain high isolation (> 30 dB). The isolation is further enhanced by loading the slots. Two mechanisms are analyzed to tune the frequency bands individually or simultaneously. Firstly, the width of the slots can be altered to tune the frequency bands. However, this method involves modification of the physical dimensions of the antenna. Secondly, fluidic vias are created on the bottom plane of the cavities. These can be filled with various dielectric liquids to achieve frequency reconfigurability without altering the physical dimensions of the antenna. To demonstrate the concepts considered, the prototype of the proposed antenna was fabricated and experimentally validated. The structure has a footprint of 0.045λg2 and an isolation exceeding 33.4 dB. The operating frequencies are tunable in the range from 3.08 to 3.84GHz (lower band) and from 4.97 to 6.33GHz (upper band) by varying the dimensions of the slots whereas the operating frequencies are reconfigurable in the range from 2.74 to 3.38GHz (lower band) and from 4.54 to 5.58GHz (upper band), by employing microfluidic approach. As a result, the working frequencies may be varied in the range from 2.74 to 3.84GHz (lower band) and from 4.54 to 6.33GHz (upper band), making this antenna diplexer a competitive candidate for several communication systems. The cross-polarization levels, front-to-back ratio, and realized gain are greater than 19 dB, 18 dB, and 2. dBi, respectively. Excellent consistency is observed between full-wave simulation results and the measurement data.

Extremely Compact Interconnected Half-Mode Cavity Antennas With Enhanced Isolation for MIMO System

We propose the interconnected half-mode cavity antennas (HMCAs) with enhanced isolation that have a very close center-to-center distance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.13 \lambda _{0} $ </tex-math></inline-formula> . First, by both tuning the differential mode (DM)-first impedance through a pair of inductors and creating an extra coupling path through the feeding branches, the half-mode of the cavity could be formed, and the isolation between the dual feeding ports in a single cavity could be greatly enhanced from 2 to 25–50 dB over the working band from 4.9 to 5.1 GHz. Then, we extend the dual-port to four-port HMCAs with a total length of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.54 \lambda _{0} $ </tex-math></inline-formula> through the connection of dual cavities, and the isolation between the adjacent cavities could be enhanced from 7 to better than 23 dB by employing the tuning lines to tune the common mode (CM)-second impedance. Furthermore, the extremely compact interconnected eight-port HMCAs are presented with a total length of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.08 \lambda _{0} $ </tex-math></inline-formula> . Finally, the experimental results also validate the effectiveness of our proposed HMCAs with excellent decoupling performance. Our proposed design should provide promising application values for the extremely compact multiple-input multiple-output (MIMO) systems.

A Shared-Aperture Dual-Band High-Efficiency Antenna Based on Groove Gap Waveguide

A shared-aperture dual-band antenna at 2.4 GHz Wi-Fi and Ku-bands is proposed in this letter. The antenna in the high-frequency band is featured by a slotted cavity configuration based on the gap waveguide technology. The slotted antenna consists of 3 × 3 slots incorporated into the top metal of the cavity. The periodic structure is loaded into the proposed antenna, which reduces the resonant frequency of the cavity. The top metal of the cavity is enlarged and four shorted screws are loaded, which achieve four half-mode cavities operated in the Wi-Fi band. Two antennas (slotted cavity antenna and dual-band antenna) are designed, fabricated, and tested. Measured results show that a −10 dB impedance bandwidth of 18.3% (13.15–15.8 GHz), a 3 dB gain bandwidth of 17.7% (13.1–15.65 GHz), and a peak gain of 14.8 dBi are realized for the cavity antenna. The impedance bandwidth of the proposed dual-band antenna covers 2.4–2.5 and 13.4–16.2 GHz. A 2 dB gain bandwidth of 16.4% (13.4–15.8 GHz) is realized. Owing to an all-metal structure that exhibits no dielectric loss, the radiation efficiency of the antenna is better than −1 dB in the whole working band. The proposed antenna shows the characteristics of high gain, high efficiency, and low cost, which is suitable for simultaneous satellite communication and Internet of Things applications.

A triple-band dual-fed frequency-flexible SIW cavity-backed slot antenna

AbstractThis article presents a novel dual-fed triple-frequency bands antenna using quarter-mode (QM)/ Eight-mode (EM) substrate integrated waveguide (SIW) cavity resonators. A V-shaped slot is etched into the patch to divide the half-mode cavity into one QM and two EM cavities. One section of the EM cavity and QM cavity are excited with the help of individual micro-strip feedlines. This configuration yields two distinct frequency bands at 4.85 GHz due to TE110 mode of the EMSIW cavity and 5.87 GHz due to TE110 mode of the QMSIW cavity confirming the self-diplexing property. Later, when both the EM cavity sections are joined with the help of two metallic strips, an additional resonance appears at 7.34 GHz due to the excitation of TE120 mode. As compared to the conventional counterparts, the proposed structure is compact and simple. The footprint of the top patch is 0.6λ1 × 0.3λ1. To authenticate the proposed idea, the design is experimentally verified, and the measured results show a good covenant with the simulated results.

Compact In-Band Full Duplexing Antenna for Sub-6 GHz 5G Applications

A novel compact in-band full duplexing antenna using a cavity-like structure for sub-6 GHz fifth-generation (5G) applications is proposed. By exploring a shared aperture cavity-like structure with two highly orthogonal modes (quarter-wavelength slot mode and half-mode cavity mode), high isolation between Tx and Rx ports is achieved. Two quarter-wavelength slots are etched on both sides of the cavity, so a shared aperture dual-mode cavity is implemented. When this cavity is fed by a pair of even–odd mode feeding structures, two orthogonal polarization modes are excited at the same frequency band. To validate the proposed concepts, a high isolation duplexing antenna with a compact size of 0.45 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.20 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.04 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is fabricated. A measured isolation greater than 43 dB is achieved over the working band from 3.4 to 3.8 GHz (LTE B42/B43 band) and its peak radiation efficiency is larger than 87%. It shows a compact size, low cost, high isolation, good bandwidth, and efficiency, which is well situated for in-band duplexing systems and 5G indoor application.

Tri-fed SIW based self-triplexer antenna for X-band applications

In this letter, an efficient and electrically compact cavity-backed self-triplexing antenna using a substrate integrated waveguide (SIW) technique is proposed. The antenna model is nested with an inverted “T”-shaped cavity and convert the rectangular SIW cavity into the two quarter mode (QM) and a half mode cavity (HM) approximately; excited through a coax probe and two micro-strip feed line separately. The proposed model operates at three distinct frequencies at 9.37 GHz, 9.86 GHz, and 10.36 GHz used for X-band wireless and radar communication systems. The self-triplexing feature is obtained with the mode perturbation concept and adequate intrinsic isolation of &gt;31 dB is observed among three input ports. The proposed antenna possesses a minimum frequency ratio, uni-directional radiation patterns with high gain, and better efficiency.

Design of half‐mode substrate integrated cavity inspired dual‐band antenna

A novel and compact design of dual-band antenna, based on substrate integrated cavity is developed. The antenna comprises a half-mode cavity, an open-ended longitudinal slot, and a printed inset-feed mechanism. Finally, the proposed design is fabricated and its results are validated. It shows the measured impedance bandwidths of 3.51% and 1.40% at 8.8 and 11.2 GHz, respectively. Their corresponding peak gain values of 5.04 and 5.01 dBi. The results of the fabricated antenna in terms of bandwidth, gain, and radiation patterns are in close agreement with their simulated counterparts. On the account cavity-backed design, the antenna exhibits unidirectional and stable radiation patterns in both bands. Moreover, the uniplanar design gives additional flexibility of easy integration with other active/passive circuits. The proposed antenna can be a suitable candidate for dual-frequency operation in X-band (8-12 GHz), especially where small frequency-ratio is stringent.

Stubbed Waveguide Cavity Filters

A new class of reduced-size waveguide filters implementing pseudoelliptic filtering functions is presented in this article. The basic structure of these filters is the stubbed waveguide cavity (SWC), which is proposed in both singleand double-stub configurations. The SWC consists of a main TE201 mode cavity, which is loaded with one or two E-plane stubs. The stubs behave as embedded half-mode cavities supporting additional resonant modes, and they are properly located so as to realize specific coupling schemes for the generation and control of transmission zeros. Depending on its configuration, a sole SWC can generate up to three poles and three transmission zeros. The design of higher order filters employing a cascade of SWCs, as well as combinations between SWCs and conventional waveguide cavities, are presented. The experimental results of a third-order filter employing one SWC (double-stub configuration) and a fifth-order filter employing two SWCs validate the feasibility of this new class of waveguide filters.

A Low-Profile Printed Cavity Antenna With Simultaneous Bandwidth and Radiation Pattern Improvement

A low-profile printed cavity antenna (PCA) under triple-mode resonance is proposed towards a simultaneous impedance bandwidth and a radiation pattern improvement. Based on the cavity model, the far-zone radiated fields of the PCA are theoretically investigated. The results demonstrate that its E -plane half-power beamwidth (HPBW) could be significantly improved by using two half-mode cavities instead of a single-patch resonator. After that, the width of the radiating patch is progressively enlarged and separated in order to excite three resonant modes for bandwidth-enhancement. Moreover, two additional conductive vias are loaded below the radiating patch in order to reduce its increased E -plane cross polarization. In final, the proposed antenna is fabricated and tested. Experimental results show that its impedance bandwidth is obviously extended to about 14.3% with appearance of three in-band attenuation poles. Meanwhile, a low-profile property with the height of 0.027 free-space wavelength is achieved. In particular, the PCA has acquired a wide E -plane HPBW of around 135°, while keeping a low cross polarization of below –20 dB in both E- and H-planes.

Beam Scanning Realized by Coupled Modes in a Single-Patch Antenna

In this letter, we introduce a novel beam scanning in a single-rectangular-patch antenna realized by coupled modes. The design exhibits radiated beams that scan as a function of frequency, but is different in its operation mechanism compared to a traditional leaky-wave antenna. The idea is to manipulate the phase difference between the fields at two radiating slots of the antenna to reform the beam. Metal vias are introduced to create two coupled half-mode cavities in the patch antenna. The mutual coupling between the two cavities makes the phase difference as a function of the operating frequency. The simulated beam scans from broadside to 43° within the 3 dB gain band. The implemented sample realizes 4.55% bandwidth of S11 with center frequency at 5.05 GHz by measurement. The beam scans from 14° to 34° within the matching band, which is confirmed by both simulation and measurement. The measured radiation efficiency within the matching band is comparable to a regular-patch antenna.

Wearable Applications of Quarter-Wave Patch and Half-Mode Cavity Antennas

The quarter-wave patch and half-mode cavity antennas are two typical designs of half-size resonator antennas that are suitable for wearable applications. Despite their similar appearance, they have distinctively different properties. In this letter, the quarter-wave patch and rectangular half-mode cavity antennas are first theoretically analyzed with a cavity model to allow a direct comparison of size and internal field distribution. On that basis, wearable realizations of those two antennas using embroidered conductive shorting/side walls are investigated. It is demonstrated through full-wave simulations that the designs need to consider the resonance frequency stability against compression at seams, and that design optimization for both antennas will benefit from taking into account all expected bending conditions. With this procedure, the overall operational bandwidth over a range of bending conditions can be markedly improved, and a drift of the resonance frequency with bending can be mitigated. Realizations of the two antennas with conductive textiles and embroidered conductive threads for operation at 2.45 GHz validate the findings.

Comparative Investigation of Half-mode SIW Cavity and Microstrip Hybrid Antenna Using Different Patch Shapes

A set of hybrid microstrip patch and semi-circular cavity antennas is introduced. The semi-circular cavity is implemented using Half-mode Substrate Integrated Waveguide (HMSIW) technique. Different shapes of the patch including rectangular, semi-circular and equilateral triangular are excited using proximity effect by the semi-circular SIW cavity at its TM010 mode. The proposed antenna structures have been excited using an inset 50 Ω microstrip line that leads to a facility of planar circuit integration. The inherent limited bandwidth of the conventional microstrip patch antenna and SIW cavity-backed slot antenna is improved about 6 to 10% depending on the type of the patch using the proposed structure. Additionally, the proposed hybrid antenna enhanced the antenna gain by about 1.5 dB in comparison with the half-mode cavity without patch. Meanwhile, the proposed hybrid antennas made on a single-layer substrate has a low fabrication cost using printed circuit board (PCB) process. Three hybrid antennas are numerically and experimentally investigated. A comparative study between the three different structures contains gain, bandwidth, Cross Polarization Level (CPL ) and Front to Back Ratio (FBR ) is presented.

D-band on-chip higher-order-mode dielectric-resonator antennas fed by half-mode cavity in CMOS technology

In this paper, on-chip higher-order-mode dielectric-resonator antennas (DRAs), fed by a half-mode-backed cavity structure using standard CMOS technology, are presented. With the dominant cavity mode (half-TEz100), the half-mode cavity-feeding structure provided a high antenna radiation efficiency. The dielectric resonators (DRs) were designed to operate at higher-order modes (TEx¿13, TEx¿15) to enhance the antenna gain. At around 135 GHz, the proposed antennas demonstrated measured gains of 6.2 dBi and 7.5 dBi for the TEx¿13 and TEx¿15 modes, respectively, with corresponding simulated radiation efficiencies of 46% and 42%. Both antennas had a measured impedance bandwidth of 7%. The proposed antennas not only accomplished high gain without occupying a large chip area, but also maintained comparable or even improved cost performance and simplicity over other on-chip antennas.

EXTENDED DOUBLET BANDPASS FILTERS IMPLEMENTED WITH MICROSTRIP RESONATOR AND FULL-/HALF-MODE SUBSTRATE INTEGRATED CAVITIES

Two extended doublet bandpass fllters with compact size and good spurious suppression characteristic are proposed. One is built up by a dual-mode microstrip resonator with a full-mode substrate integrated cavity, while the other is composed of a microstrip resonator and a half-mode cavity. The relationship between the location of their transmission zeros and the impedance ratio of the microstrip resonator is analyzed theoretically. Our proposed fllters only occupy the areas of 0:69‚ 2 =r and 0:51‚ 2 =r, and they also have wide upper stopband. The predicted performances are demonstrated by the reasonable agreement obtained between their simulated and measured S-parameters.