Showing papers on "Patch antenna published in 2016"

A Low-Profile High-Gain and Wideband Filtering Antenna With Metasurface

Abstract: A low-profile, high-gain, and wideband metasurface (MS)-based filtering antenna with high selectivity is investigated in this communication. The planar MS consists of nonuniform metallic patch cells, and it is fed by two separated microstrip-coupled slots from the bottom. The separation between the two slots together with a shorting via is used to provide good filtering performance in the lower stopband, whereas the MS is elaborately designed to provide a sharp roll-off rate at upper band edge for the filtering function. The MS also simultaneously works as a high-efficient radiator, enhancing the impedance bandwidth and antenna gain of the feeding slots. To verify the design, a prototype operating at 5 GHz has been fabricated and measured. The reflection coefficient, radiation pattern, antenna gain, and efficiency are studied, and reasonable agreement between the measured and simulated results is observed. The prototype with dimensions of 1.3 $\lambda_{0}\times1.3\ \lambda_{0}\times0.06\ \lambda_{0}$ has a 10-dB impedance bandwidth of 28.4%, an average gain of 8.2 dBi within passband, and an out-of-band suppression level of more than 20 dB within a very wide stop-band.

Radiation Pattern-Reconfigurable Wearable Antenna Based on Metamaterial Structure

Abstract: A pattern-reconfigurable wearable antenna is designed based on a metamaterial structure. By reconfiguring the dispersion curve of the transmission line, the patch antenna can resonate at the zeroth-order mode or the +1 mode, yielding a broadside or an omnidirectional radiation pattern, respectively. The antenna is fabricated with textile material targeting wearable applications. The impedance bandwidth covers the 2.4 GHz Industrial, Scientific, and Medical (ISM) band in both operating states. The antenna is also simulated on a human tissue model, illustrating that the specific absorption rate is well below the European standard threshold. The bending configurations are also discussed for the proposed antenna.

Dual-Polarized Filtering Antenna With High Selectivity and Low Cross Polarization

Abstract: This paper presents a dual-polarized patch antenna with quasi-elliptic bandpass responses. The proposed antenna is mainly composed of a feeding network, a driven patch, and a stacked patch, with its entire height being $0.09\lambda $ . The feeding network consists of two orthogonal H-shaped lines that coupled to the driven patch, each for one polarization. The elaborately-designed feeding lines not only ensure a sharp roll-off rate at the lower band edge, but also help to achieve low cross polarization and high isolation between two feeding ports. On the other hand, the upper stacked patch provides improved suppression levels at the upper stopband and also an enhanced gain within passband. Consequently, a compact dual-polarized antenna with satisfying filtering performance is obtained, without using extra filtering circuits. For demonstration, an antenna is designed to fit the specification of LTE band (2.49–2.69 GHz). The implemented antenna achieves an average a gain of 9 dBi, a cross-polarization ratio of 29 dB, an isolation of 35 dB within LTE band. The out-of-band suppression level is more than 40 dB within the 2G and 3G frequency bands from 1.71–2.17 GHz. It can be used as the antenna elements in multiband base station antenna arrays to reduce the mutual coupling.

Metasurface Superstrate Antenna With Wideband Circular Polarization for Satellite Communication Application

Abstract: A new wideband circularly polarized antenna using metasurface superstrate for C-band satellite communication application is proposed in this letter. The proposed antenna consists of a planar slot coupling antenna with an array of metallic rectangular patches that can be viewed as a polarization-dependent metasurface superstrate. The metasurface is utilized to adjust axial ratio (AR) for wideband circular polarization. Furthermore, the proposed antenna has a compact structure with a low profile of 0.07λ 0 ( λ 0 stands for the free-space wavelength at 5.25 GHz) and ground size of 34.5×28 mm 2 . Measured results show that the -10-dB impedance bandwidth for the proposed antenna is 33.7% from 4.2 to 5.9 GHz, and 3-dB AR bandwidth is 16.5% from 4.9 to 5.9 GHz with an average gain of 5.8 dBi. The simulated and measured results are in good agreement to verify the good performance of the proposed antenna.

Stacked Patch Antenna With Dual-Polarization and Low Mutual Coupling for Massive MIMO

Abstract: Massive multiple input and multiple output (MIMO) has attracted significant interests in both academia and industry. It has been considered as one of most promising technologies for 5G wireless systems. The large-scale antenna array for base stations naturally becomes the key to deploy the Massive MIMO technologies. In this communication, we present a dual-polarized antenna array with 144 ports for Massive MIMO operating at 3.7 GHz. The proposed array consists of 18 low profile subarrays. Each subarray consists of four single units. Each single antenna unit consists of one vertically polarized port and one horizontally polarized port connected to power splitters, which serve as a feeding network. A stacked patch design is used to construct the single unit with the feeding network, which gives higher gain and lower mutual coupling within the size of a conversional dual-port patch antenna. Simulation results of the proposed single antenna unit, sub-array, and Massive MIMO array are verified by measurement.

Bandwidth Enhancement of a Single-Feed Circularly Polarized Antenna Using a Metasurface: Metamaterial-based wideband CP rectangular microstrip antenna.

Abstract: Wireless systems manufacturers desire a low-profile, wideband, circularly polarized (CP) antenna. Generally, a single-feed CP microstrip antenna (CPMA) has a simple configuration but is hindered by a narrow, 3-dB axial ratio (AR) bandwidth. The bandwidth of a multiple-feed CPMA can be enhanced but requires a complicated and larger feeding network. Many techniques have been employed to improve AR bandwidth, such as using dual-feed, network-based structures [1], stacked patches [2]?[3], array antennas with sequential feeding network [4], and multilayered structures [5]. However, these CP antennas are based on multiradiating patches or complicated feeding structures.

Gain-Enhanced Patch Antennas With Loading of Shorting Pins

Abstract: A new gain-enhanced patch antenna with loading of shorting pins is proposed in this paper. Four metallic pins are symmetrically placed in the two diagonals of a square patch resonator to electrically short the patch and ground plane. These shorting pins tremendously perturb the field distribution beneath the patch due to their shunt inductive effect. As these four pins are moved outward along the two orthogonal diagonals away from the center, their influence on the field distribution over the patch is strengthened to gradually raise its dominant mode, i.e., TM010 mode, resonant frequency as the pin-to-pin spacing is enlarged. At a fixed resonant frequency, the overall area of this proposed patch antenna with four pins results to be increased. As such, its radiation directivity or gain gets to be enhanced due to the enlarged antenna area. After extensive analysis is executed, two square patch antennas with and without loaded pins are designed and fabricated. The simulated and measured results agree with each other, and they have evidently demonstrated that the radiation directivity can be enhanced up to 11.0 dBi, or about 2.9 dB increment, by virtue of the proposed approach.

Dual-Band Patch Antenna With Filtering Performance and Harmonic Suppression

Abstract: A novel design of a dual-band antenna with integrated filtering performance is proposed. A low-profile aperture-coupled U-slot patch antenna is employed for the dual-band operation with a uniform polarization, which is fed by a dual-mode stub-loaded resonator (SLR). The U-slot patch works as a dual-mode resonator of the dual-band filter as well as the radiation element. The odd- and even-modes of the SLR are coupled and tuned with the U-slot patch, generating two second-order operation bands at 3.6 and 5.2 GHz. Compared with the traditional patch antenna, the proposed antenna exhibits improved bandwidth and frequency selectivity. In addition, the bandwidths can be controlled by adjusting the coupling strength between the SLR and the patch. Furthermore, the higher order harmonics can be suppressed over a broadband without increasing the footprint of the design. The measured and simulated results agree well with each other, showing excellent performance in terms of impedance matching, bandwidths, second-order filtering, out-of-band rejection, cross-polarization discrimination, and gains at both the bands.

Bending and On-Arm Effects on a Wearable Antenna for 2.45 GHz Body Area Network

Abstract: Three types of flexible textile antennas for 2.45 GHz body area network (BAN) are compared in this letter. Two types of conducting materials are used to form radiation patch and ground plane; they are called copper foil tape (CFT, 0.05 mm thickness) and Shieldex (SH, 0.13 mm thickness, 0.009 Ohm surface resistivity). The substrate is a thin felt with relative permittivity of 1.2 and the thickness of 2 mm. In order to satisfy these requirements of small frequency shifting when the antenna is bent and placed on human body, two shorting probes are used to connect the radiation patch and ground plane. Compared to the antenna without shorting probes, the size of proposed antenna is reduced from 96 ×47 to 70 ×25 mm 2 , and the measured minimum value of S11 in free space is also decreased from -14.59 to -33.30 dB. Furthermore, an antenna with smaller size of 46 ×25 mm 2 is designed by modifying the proposed structure, and it can act as a wearable antenna as well.

A Novel Simple and Compact Microstrip-Fed Circularly Polarized Wide Slot Antenna With Wide Axial Ratio Bandwidth for C-Band Applications

Abstract: This communication presents a design of a new compact circularly polarized (CP) slot antenna fed by a microstrip feedline. The 3-dB axial ratio band can be achieved by simply protruding a horizontal stub from the ground plane toward the center of the wide slot (WS) and then feeding the WS with a microstrip feedline positioned to the side of the WS, underneath the protruded stub. The feedline and metallic stub are perpendicular to each other, and they resemble a T shape when viewed from the top. The proposed antenna is fabricated with an area of $25 \times 25\;{\rm mm}^{2}$ . Measurement results show that the antenna attains an ${\rm S}_{11}\le-10\;{\rm dB}$ impedance matching bandwidth of 90.2%, from 3.5 to 9.25 GHz, and a broadband 3 dB-AR bandwidth of 40%, ranging from 4.6 to 6.9 GHz. A peak gain of 0.8–4.5 dBi is achieved within the AR band. The proposed antenna is suitable for circular polarization applications in C band.

Bandwidth Enhancement of a Monopolar Patch Antenna With V-Shaped Slot for Car-to-Car and WLAN Communications

Abstract: A monopolar patch antenna with a V-shaped slot for car-to-car (C2C) and wireless local area network (WLAN) communications is presented in this paper. To widen the impedance bandwidth of the antenna, techniques for adding a shorting pin and a V-shaped slot are applied to an equilateral triangular patch. By properly placing the shorting pins on an equilateral triangular patch, two operating modes, i.e., TM10 and TM20, are obtained. The presence of the V-shaped slot can generate an additional TM11 mode. These three resonances found in the operating frequency bandwidth resulted in a wideband characteristic. The proposed antenna can operate from 4.82 to 6.67 GHz for the reflection coefficient $\le -$ 10 dB with the gain of around 5.0 dBi. In addition, an omnidirectional radiation pattern is yielded by a coaxial center-fed probe excitation. The antenna has a thickness of 0.09 $\boldsymbol{\lambda}_\mathbf{g}$ (at the center frequency of 5.5 GHz), which is easily hidden on the roof of a vehicle for C2C communication. This proposed design can also be used as indoor base-station antennas for WLAN communication.

A Compact Microstrip-Fed Patch Antenna With Enhanced Bandwidth and Harmonic Suppression

Abstract: A single-layer microstrip-fed patch antenna with capabilities of both bandwidth enhancement and harmonic suppression is proposed. For this purpose, a pair of $\lambda $ /4 microstrip-line resonators is introduced and coupled in proximity to a rectangular patch. The wideband property can be obtained by making effective use of the two resonances introduced by the radiating patch and nonradiating $\lambda $ /4 resonators. Different from other reported dual-resonance patch antennas, the proposed antenna does not require the electrically thick substrate, so it has attractive low-profile property. Thanks to the good features of $\lambda $ /4 resonators and capacitive feeding scheme, harmonic radiating modes of the patch antenna can be significantly suppressed as highly demanded in modern highly integrated communication systems. The working principle, equivalent circuit, and design procedure are extensively described. Finally, a prototype antenna operating at 4.9 GHz is designed and fabricated. The measured results show that its bandwidth is 2.7 times wider than that of the traditional insert-fed patch counterpart, and the harmful spurious radiation from other higher order radiating modes has been effectively suppressed.

Infill-Dependent 3-D-Printed Material Based on NinjaFlex Filament for Antenna Applications

Abstract: This letter presents one of the first examples of the exploitation of 3-D printing in the fabrication of microwave components and antennas. Additive manufacturing represents an enabling technology for a wide range of electronic devices, thanks to its inherent features of fast prototyping, the reasonable accuracy, fully 3-D topologies, and the low fabrication cost. A novel 3-D printable flexible filament, based on NinjaFlex, has been adopted for manufacturing the substrate of a 3-D printed patch antenna. NinjaFlex is a recently introduced material with extraordinary features in terms of mechanical strain, flexibility, and printability. Initially, the electrical properties of this material are investigated at 2.4 GHz using the ring resonator technique. The capability of selectively changing the dielectric constant by modifying the printed material density by fine-tuning printing infill percentage is verified experimentally. Subsequently, a square patch antenna is prototyped through 3-D printing and measured to validate the manufacturing technology. Finally, exploiting mechanical flexibility properties of NinjaFlex, the antenna is tested under different bending conditions.

Mutual Coupling Suppression Between Two Closely Spaced Microstrip Antennas With an Asymmetrical Coplanar Strip Wall

Abstract: This letter describes an asymmetrical coplanar strip (ACPS) wall to suppress the mutual coupling between two closely spaced 5.8-GHz microstrip antennas. The ACPS wall, which is inserted vertically between the two antennas, introduces an additional coupling path to reduce the antenna coupling, occupying just a small area between the two antennas. The decoupling effect of the proposed structure is verified by the simulation and measurement. The experimental results show that the achieved isolation is better than 35 dB and reaches a maximum of 54.3 dB at 5.8 GHz, with an extremely close antenna distance of 0.03λ0 (edge-to-edge distance). The measured patterns indicate that the proposed structure also improves the radiation of the microstrip antenna.

Three dimensional (3d) antenna structure

Abstract: An apparatus includes a substrate package and a three dimensional (3D) antenna structure formed in the substrate package. The 3D antenna structure includes multiple substructures to enable the 3D antenna structure to operate as a beam-forming antenna. Each of the multiple substructures has a slanted-plate configuration or a slanted-loop configuration.

Design and Experimental Investigation of a Compact Circularly Polarized Integrated Filtering Antenna for Wearable Biotelemetric Devices

Abstract: A compact circularly polarized (CP) integrated filtering antenna is reported for wearable biotelemetric devices in the 2.4 GHz ISM band. The design is based on a mutual synthesis of a CP patch antenna connected to a bandpass filter composed of coupled stripline open-loop resonators, which provides an integrated low-profile radiating and filtering module with a compact form factor of $0.44\lambda_{0}\times 0.44\lambda_{0}\times 0.04\lambda_{0}$ . The optimized filtering antenna is fabricated and measured, achieving an $S_{11} , an axial ratio of less than 3 dB and gain higher than 3.5 dBi in the targeted ISM band. With the integrated filtering functionality, the antenna exhibits good out-of-band rejection over an ultra-wide frequency range of 1–6 GHz . Further full-wave simulations and experiments were carried out, verifying that the proposed filtering antenna maintains these desirable properties even when mounted in close proximity to the human body at different positions. The stable impedance performance and the simultaneous wide axial ratio and radiated power beam widths make it an ideal candidate as a wearable antenna for off-body communications. The additional integrated filtering functionality further improves utility by greatly reducing interference and crosstalk with other existing wireless systems.

Design of Phased Arrays of Series-Fed Patch Antennas With Reduced Number of the Controllers for 28-GHz mm-Wave Applications

Abstract: New modified 2 × 2 and 3 × 3 series-fed patch antenna arrays with beam-steering capability are designed and fabricated for 28-GHz millimeter-wave applications. In the designs, the patches are connected to each other continuously and in symmetric 2-D format using the high-impedance microstrip lines. In the first design, 3-D beam-scanning range of ± 25° and good radiation and impedance characteristics were attained by using only one phase shifter. In the second one, a new mechanism is introduced to reduce the number of the feed ports and the related phase shifters (from default number 2 N to the reduced number N + 1 in the serial feed (here N = 3) and then the cost, complexity, and size of the design. Here, good scanning performance of a range of ± 20°, acceptable sidelobe level, and gain of 15.6 dB are obtained. These features allow to use additional integrated circuits to improve the gain and performance. A comparison to the conventional array without modification is done. The measured and simulated results and discussions are presented.

S-shaped periodic defected ground structures to reduce microstrip antenna array mutual coupling

Abstract: A novel S-shaped periodic defected ground structure (PDGS) is proposed to reduce mutual coupling between antenna elements. Coplanar placed antenna elements work at the same frequency band with centre frequency 2.57 GHz. Centre-to-centre distance between the antenna elements is 50 mm which is ~0.43λ. The PDGS is three S-shaped defected ground structure units placed between microstrip antenna elements. By using the proposed PDGS, more than 40 dB mutual coupling reduction between microstrip antenna elements is achieved.

High-Gain Circularly Polarized Microstrip Patch Antenna With Loading of Shorting Pins

Abstract: A single-fed microstrip patch antenna (MPA) with loading of shorting pins for high-gain circularly polarized (CP) radiation is proposed in this paper. Two sets of metallic pins are symmetrically placed along the two orthogonal diagonals of a square patch radiator at first. Due to the shunt inductive effect brought by these shorting pins, the resonant frequency of the dominant mode in this MPA is progressively tuned up so as to enlarge the electrical size of this pin-loaded patch resonator and to enhance its radiation directivity. After the optimal loading position is investigated for maximum directivity of linear polarization, one pair of the inner pins is slightly shifted in an offset to properly separate the two degenerate modes, so that the CP radiation can be excited. Moreover, upon request, either left-handed or right-handed circular polarization can be obtained by means of different position-offset scheme of the inner pins along the diagonals. After extensive analysis is executed, two equal-size CP MPAs with and without shorting pins are fabricated and tested. Simulated and measured results show good agreement and demonstrate that the CP directivity is enhanced from 8.0 (conventional MPA) to 10.8 dBic, indicating a 2.8-dB increment by means of the proposed approach.

Design of Compact F-Shaped Slot Triple-Band Antenna for WLAN/WiMAX Applications

Abstract: This communication presents a small, low-profile planar triple-band microstrip antenna for WLAN/WiMAX applications. The goal of this communication is to combine WLAN and WiMAX communication standards simultaneously into a single device by designing a single antenna that can excite triple-band operation. The designed antenna has a compact size of $19 \times 25\;\text{mm}^{2}$ ( $0.152 \lambda_{0}\;\times 0.2 \lambda_{0}$ ). The proposed antenna consists of F-shaped slot radiators and a defected ground plane. Since only two F-shaped slots are etched on either sides of the radiator for triple-band operation, the radiator is very compact in size and simple in structure. The antenna shows three distinct bands I from 2.0 to 2.76, II from 3.04 to 4.0, and III from 5.2 to 6.0 GHz, which covers entire WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5) bands. To validate the proposed design, an experimental prototype has been fabricated and tested. Thus, the simulation results along with the measurements show that the antenna can simultaneously operate over WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5 GHz) frequency bands.

Design of a Low-Profile Dual-Polarized Stepped Slot Antenna Array for Base Station

Abstract: In this letter, a microstrip-fed dual-polarized stepped-impedance (SI) slot antenna element with a low profile is first proposed. The antenna is composed of two pairs of SI slots excited by two orthogonal stepped microstrip feedlines. The broadband characteristic is achieved by combining the fundamental and spurious resonances of the SI slot resonators, while the good cross polarization is mainly due to the introduction of the shorting pins. Secondly, based on the proposed antenna, a four-element antenna array is designed, constructed, and measured for base-station applications. Measured results demonstrate the bandwidths (return loss ) of the antenna array are 46.9% (1.55-2.5 GHz) and 38.7% (1.69-2.5 GHz) for Port 1 and Port 2, respectively. The isolation between the two ports is greater than 35 dB, whereas the cross-polarization level maintains lower than -27 dB across the entire operating band. In addition, the antenna array prototype achieves average gains of 13.5 and 13.9 dBi for horizontal polarization and vertical polarization, respectively.

An Integrated Filtering Antenna Array With High Selectivity and Harmonics Suppression

Abstract: In this paper, a new design of an antenna array with integrated functions of filtering, harmonics suppression, and radiation is proposed. The device employs a multi-port network of coupled resonators, which is synthesized and designed as a whole to fulfill the functions of filtering, power combination/division, and radiation. The 50- $\Omega $ interfaces between the cascaded filter, power divider, and antenna in traditional RF front-ends are eliminated to achieve a highly integrated and compact structure. A novel resonator-based four-way out-of-phase filtering power divider is proposed and designed. It is coupled to the patch array, rendering a fourth-order filtering response. The coupling matrix of the resonator network is synthesized. The physical implementations of the resonators and their couplings are detailed. Compared to a traditional patch array, the integrated filtering array shows an improved bandwidth and frequency selectivity. In addition, the harmonic of the antenna array is suppressed due to the use of different types of resonators. To verify the concept, a $2\times 2$ filtering array at S-band is designed, prototyped, and tested. Good agreement between simulations and measurements has been achieved, demonstrating the integrated filtering antenna array has the merits of wide bandwidth, high frequency selectivity, harmonics suppression, stable antenna gain, and high polarization purity.

Compact-Size Low-Profile Wideband Circularly Polarized Omnidirectional Patch Antenna With Reconfigurable Polarizations

Abstract: A compact-size low-profile wideband circularly polarized (CP) omnidirectional antenna with reconfigurable polarizations is presented in this communication. This design is based on a low-profile omnidirectional CP antenna which consists of a vertically polarized microstrip patch antenna working in $\text{TM}_{01}/\text{TM}_{02}$ modes and sequentially bended slots etched on the ground plane for radiating horizontally polarized electric field. The combined radiation from both the microstrip patch and the slots leads to a CP omnidirectional radiation pattern. The polarization reconfigurability is realized by introducing PIN diodes on the slots. By electronically controlling the states of the PIN diodes, the effective orientation of the slots on ground plane can be changed dynamically and the polarization of antenna can be altered between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The proposed antenna exhibits a wide-operational bandwidth of 19.8% (2.09–2.55 GHz) with both axial ratio below 3 dB and return loss above 10 dB when radiates either LHCP or RHCP waves. Experimental results show good agreement with the simulation results. The present design has a compact size, a thickness of only $0.024\lambda$ and exhibits stable CP omnidirectional conical-beam radiation patterns within the entire operating frequency band with good circular polarization.

Radar Cross Section Reduction of a Microstrip Antenna Based on Polarization Conversion Metamaterial

Abstract: A novel method aimed at reducing radar cross section (RCS) under incident waves with both $x$ - and $y$ -polarizations, with the radiation characteristics of the antenna preserved, is presented and investigated. The goal is accomplished by the implementation of the polarization conversion metamaterial (PCM) and the principle of passive cancellation. As a test case, a microstrip patch antenna is simulated and experimentally measured to demonstrate the proposed strategy for dramatic radar cross section reduction (RCSR). Results exhibit that in-band RCSR is as much as 16 dB compared to the reference antenna. In addition, the PCM has a contribution to a maximum RCSR value of 14 dB out of the operating band. With significant RCSR and unobvious effect on the radiation performance of the antenna, the proposed method has a wide application for the design of other antennas with a requirement of RCS control.

Fixed-Frequency Beam Steering of Microstrip Leaky-Wave Antennas Using Binary Switches

Abstract: This paper presents a novel, easy-to-fabricate and operate, single-layer leaky-wave antenna (LWA) that is capable of digitally steering its beam at fixed frequency using only two values of bias voltages, with very small gain variation and good impedance matching while scanning. Steering the beam of LWAs in steps at a fixed frequency, using binary switches, is investigated, and a new half-width microstrip LWA (HW-MLWA) is presented. The basic building block of the antenna is a reconfigurable unit cell, switchable between two states. A macrocell is created by combining several reconfigurable unit cells, and the periodic LWA is formed by cascading identical macrocells. A prototype HW-MLWA was designed, fabricated, and tested to validate the concept. To achieve fixed-frequency beam scanning, a gap capacitor in each unit cell is independently connected or disconnected using a binary switch. By changing the macrocell states, the reactance profile at the free edge of the microstrip and hence the main beam direction is changed. The prototyped antenna can scan the main beam between 31° and 60° at 6 GHz. The measured peak gain of the antenna is 12.9 dBi at 6 GHz and gain variation is only 1.2 dB.

Multiband Antenna for WiFi and WiGig Communications

Abstract: This letter presents a low-cost printed circuit board (PCB)-based dual-band antenna for future wireless local area network (WLAN) applications. The antenna is designed to fully cover both WiFi channels (2.4/5.2/5.8 GHz) and Wireless Gigabit Alliance (WiGig) channels (57-64 GHz). At the WiFi frequency bands, the antenna is based on a printed monopole, while at the WiGig frequency band, a wideband higher-order-mode patch antenna is adopted. A compact microstrip resonance cell (CMRC) low-pass filter is also designed to allow feeding the monopole antenna at WiFi frequency bands while isolating the monopole from the patch for WiGig operation. The design is fabricated by standard PCB and plated-through-hole technologies, and its performance is validated by measurement.

Mutual Coupling Reduction for High-Performance Densely Packed Patch Antenna Arrays on Finite Substrate

Abstract: This paper reports on an effective mutual coupling suppression technique in which a metamaterial superstrate is placed in between the elements of densely packed microstrip phased array. Modified complementary split ring resonators are printed on the decoupling superstrate slab which caters for both surface and space wave effects. A detailed analysis of this proposed scheme is carried out on a low as well as on a high-permittivity substrate. Coupling suppression of 27 and 11 dB is achieved experimentally on the low- and high-permittivity substrates, respectively, with an element separation of $\lambda_{o}/8$ . The design is compact and easy to realize and it removes drawback of poor front-to-back ratio previously reported in other decoupling techniques. In addition to high-coupling suppression, the decoupling slab can be added or removed in real time which makes this technique versatile for various applications having stringent performance requirements.

Design of Self-Diplexing Substrate Integrated Waveguide Cavity-Backed Slot Antenna

Abstract: In this letter, a novel design technique to realize planar self-diplexing slot antenna using substrate integrated waveguide (SIW) technology is presented. The proposed antenna uses a bowtie-shaped slot backed by SIW cavity, which is excited by two separate feedlines to resonate at two different frequencies in X -band (8–12 GHz). By properly optimizing the antenna dimensions, a high isolation of better than 25 dB between two input ports is achieved, which helps to introduce self-diplexing phenomenon in the proposed design. The behavior of the individual cavity modes at two resonant frequencies is explained using half-mode theory. The proposed antenna resonates at 9 and 11.2 GHz with unidirectional radiation pattern and a high gain of 4.3 and 4.2 dBi, respectively.

Design of a Reconfigurable Miniaturized Microstrip Antenna for Switchable Multiband Systems

Abstract: In this letter, a novel printed frequency-reconfigurable microstrip square slot antenna for switchable Bluetooth, WiMAX, and WLAN applications is presented. The proposed antenna has a small size of $20 \times 20~\hbox{mm}^2$ in order to be able to cover lower frequencies; as for Bluetooth applications, miniaturization techniques such as modification of the ground plane and inserting an adjustable backplane cross-shaped sleeve have been employed. Moreover, by implementation of p-i-n diodes within the antenna structure, switchable frequency responses are achieved. The presented antenna has a small size while providing suitable switchable radiations at 2.3–2.51 GHz $({\rm BW} = 8.7\%)$ Bluetooth, 3.35–3.75 GHz $({\rm BW} = 11.2\%)$ WiMAX, and 4.95–5.53 GHz $({\rm BW}=11\%)$ WLAN.

A Compact Filtering Dielectric Resonator Antenna With Wide Bandwidth and High Gain

Abstract: A rectangular filtering dielectric resonator antenna (FDRA) with low profile, wide bandwidth, and high gain is first investigated in this communication. It is fed by a microstrip-coupled slot from bottom, with open stub of the microstrip feedline elaborately designed to provide two radiation nulls at band edges for a filtering function. A separation is introduced in the slot to provide a good suppression level in lower stopband, while two parasitic strips are parallelly added to the microstrip feedline to offer good suppression in the upper stopband, and consequently, a compact FDRA with a quasi-elliptic bandpass response is obtained without involving specific filtering circuits. Based on the design, a modified DRA fed by a pair of separated slots is proposed to further enhance the gain by $\sim 4$ dB. A prototype operating at 5 GHz has been fabricated and measured for demonstration. The reflection coefficient, the radiation pattern, and the antenna gain are studied, and reasonable agreement between the measured and simulated results is observed. The prototype has a 10-dB impedance bandwidth of 20.3%, an average gain of 9.05 dBi within passband, and an out-of-band suppression level of more than 25 dB within a wide stopband.