Showing papers on "Patch antenna published in 2017"

Broadband Printed-Dipole Antenna and Its Arrays for 5G Applications

Abstract: In this letter, we propose a broadband printed-dipole antenna and its arrays for fifth-generation (5G) wireless cellular networks. To realize a wide frequency range of operation, the proposed antenna is fed by an integrated balun, which consists of a folded microstrip line and a rectangular slot. For compactness, the printed dipole is angled at 45°. The single-element antenna yields an |S 11 | <;-10-dB bandwidth of 36.2% (26.5-38.2 GHz) and a gain of 4.5-5.8 dBi. We insert a stub between two printed-dipole antennas and obtain a low mutual coupling of <;-20 dB for a 4.8-mm center-to-center spacing (0.42-0.61 λ at 26-38 GHz). We demonstrate the usefulness of this antenna as a beamforming radiator by configuring 8-element linear arrays. Due to the presence of the stubs, the arrays resulted in a wider scanning angle, a higher gain, and a lower sidelobe level in the low-frequency region.

A Dual-Port Triple-Band L-Probe Microstrip Patch Rectenna for Ambient RF Energy Harvesting

Abstract: A dual-port triple-band L-probe microstrip patch rectenna design for ambient RF energy harvesting using the GSM-900, GSM-1800, and UMTS-2100 bands is described. The compact dual-port L-probe patch antenna is implemented by stacking two single-port patch antennas back to back. Each port can independently harvest RF signal from a half-space with gain greater than 7 dBi, and together with both ports in a dc combining configuration, the antenna can acquire RF energy from nearly all directions. We also provide a design for a high-efficiency triple-band rectifier operating at GSM-900, GSM-1800, and UMTS-2100, which is replicated on each port and concatenated together to allow dc combining and near doubling of the output dc voltage. Measurement results show that our prototyped dual-port triple-band rectenna can receive RF power from nearly all directions with an efficiency of greater than 40% and an output voltage of more than 600 mV when the power density is greater than 500 $\mu \mathrm{W}/\mathrm{m}^{2}$ .

Isolation Enhancement in Patch Antenna Array With Fractal UC-EBG Structure and Cross Slot

Abstract: A compact patch antenna array with high isolation by using two decoupling structures including a row of fractal uniplanar compact electromagnetic bandgap (UC-EBG) structure and three cross slots is proposed. Simulated results show that significant improvement in interelement isolation of 13 dB is obtained by placing the proposed fractal UC-EBG structure between the two radiating patches. Moreover, three cross slots etched on the ground plane are introduced to further suppress the mutual coupling. The design is easy to be manufactured without the implementation of metal vias, and a more compact array with the edge-to-edge distance of 0.22 λ0 can be facilitated by a row of fractal UC-EBG, which can be well applied in the patch antenna array.

A Low-Profile Aperture-Coupled Microstrip Antenna With Enhanced Bandwidth Under Dual Resonance

Abstract: A low-profile aperture-coupled microstrip patch antenna (MPA) using the TM10 and TM30 resonant modes to enhance the impedance bandwidth is proposed in this paper. Based on the cavity model for a square MPA, the TM10 and TM30 modes as well as both higher odd-order and even-order modes between them can be characterized. In order to combine the dual radiative resonant modes for a wide impedance bandwidth, a rectangular radiating patch with an aperture-coupled feeder is employed and theoretically investigated at first, aiming to demonstrate that all of the undesired modes between them can be removed effectively. After that, by loading the shorting pins properly underneath the patch, the resonant frequency of TM10 mode is shown to progressively turn up with slight effect on that of TM30 mode. As a result, these two radiative modes can be allocated in proximity to each other, resulting in a wide impedance bandwidth with a stable radiation pattern and the same far-field polarization. Moreover, the principal parameters of the MPA have been extensively studied in order to investigate the sensitivity in input impedance of the aperture-fed patch antenna. Finally, the proposed antenna is fabricated and measured. Simulated and measured results are found in good agreement with each other and illustrate that the antenna achieves a wide impedance bandwidth of about 15.2% in fraction or 2.32–2.70 GHz under $\vert \text{S}_{\mathrm {\mathbf {11}}}\vert dB, while keeping a low profile property with the height of 0.032 free-space wavelength. Besides, a stable gain varied from 3 to 6.8 dBi within the whole operating band is also obtained.

Dual-Band Dual-Mode Textile Antenna on PDMS Substrate for Body-Centric Communications

Abstract: A dual-band antenna for off- and on-body communications in the 2.45- and 5.8-GHz Industrial, Scientific, and Medical bands is presented. The two radiation characteristics, i.e., patch-like radiation for the off-body link and monopole-like radiation for the on-body link, are achieved by utilizing inherently generated TM $_{11}$ and TM $_{02}$ modes of a circular patch antenna. A shorting pin and two arc-shaped slots are employed to tune both modes to the desired operating frequencies. This approach allows a realization of a dual-band dual-mode antenna with a very simple structure, i.e., a single radiator with a simple feed. A further advantage of the proposed antenna is its realization using a silver fabric integrated onto a flexible polydimethylsiloxane substrate that makes it more practical for wearable applications. An experimental investigation of the antenna performance has been carried out in free space and on a semisolid human muscle equivalent phantom, which shows a robust performance against the human body loading effect. When placed on the phantom, the measured bandwidths of 84 and 247 MHz in the 2.45- and 5.8-GHz bands, respectively, are achieved with the corresponding peak gains of 4.16 and 4.34 dBi, indicating a promising candidate for body-centric communications.

Low-Profile Dual-Band Filtering Patch Antenna and Its Application to LTE MIMO System

Abstract: This paper presents a low-profile dual-band filtering antenna element and its application to long-term evolution (LTE) multiple-input multiple-output (MIMO) system for wireless customer premise equipments (CPEs). The proposed element consists of two separate U-shaped patches operating at different frequencies and a multistub microstrip feed line. For size miniaturization, the smaller U-shaped patch is embedded in the larger one. In addition, the multistub feed line can generate two controllable resonant modes as well as two nulls in realized gain at the boresight direction. Since the modes of the patches and multistub feed line can be controlled individually, the two operating bands can be tuned to desired frequencies. Also, the radiation nulls in boresight gain can be controlled, high roll-off rate and out-of-band radiation rejection levels are thus obtained. For demonstration, a low profile ( $0.009\lambda _{0})$ dual-band filtering antenna element operating at 1.9 and 2.6 GHz for TD-LTE applications (B39- and B38-bands) is implemented. Dual-band bandpass responses and four radiation nulls are observed in the experiment. Measured in-band gains are 6.7 and 7.3 dBi, whereas out-of-band gains are less than −10 dBi. Based on this element, a four-element MIMO antenna is further designed for LTE CPEs, where low profile and high integration of multiple components are required. A low mutual coupling of less than −19.2 dB and the low envelope correlation coefficients of better than 0.2 are obtained with a small edge-to-edge spacing of $0.15\lambda _{0}$ .

Realization of Low Scattering for a High-Gain Fabry–Perot Antenna Using Coding Metasurface

Abstract: We present a novel method to design a conventional Fabry–Perot (F-P) antenna but with low scattering. Combining a coding metasurface and an F-P antenna together could effectively reduce the scattering and keep high gain simultaneously. The coding element consists of two layers of square metallic patches printed on both sides of a dielectric substrate. The bottom metallic patch helps form a partially reflecting surface (PRS) for the F-P antenna, while the upper metallic patch is utilized to construct the coding metasurface with an optimized coding sequence, aiming to reduce the scattering of the F-P antenna by redirecting electromagnetic energies in all directions. Based on the specially designed coding metasurface, a good scattering reduction without degrading the radiation performance of the F-P antenna is achieved. Both simulated and experimental results demonstrate the excellent performance of the proposed antenna, with a peak measured gain of 19.8 dBi and a significant scattering reduction in the frequency range of 8–12 GHz.

A Differential-Fed Microstrip Patch Antenna With Bandwidth Enhancement Under Operation of TM 10 and TM 30 Modes

Abstract: A differential-fed microstrip patch antenna (MPA) with bandwidth enhancement is proposed under the operation of TM10 and TM30 resonant modes in a single patch resonator. Initially, a rectangular differential-fed MPA is theoretically investigated so as to demonstrate that all of the undesired modes between the TM10 and TM30 modes are suppressed or removed out effectively. Then, by symmetrically introducing two pairs of shorting pins, the resonant frequency of TM10 mode is progressively turned up. After that, with the help of two long slots, the resonant frequency of TM30 mode is decreased with slight effect on that of TM10 mode. Furthermore, a short slot is inserted at the center of the patch to cancel the parasitic inductances of the shorting pins and probe feeds. With this arrangement, these two radiative resonant modes are moved in proximity to each other for wideband antenna. Finally, the proposed differential-fed MPA is fabricated and measured. Experimental results illustrate that the impedance bandwidth ( $\vert S_{{{\text {dd}11}}}\vert dB) of the antenna has gained a tremendous increment up to about 13% (1.88–2.14 GHz), while keeping a low profile property with the height of 0.029 free-space wavelength. Additionally, the antenna has achieved a stable gain varied from 5.8 to 7 dBi over the operating band.

Wideband Pattern-Reconfigurable Antenna with Switchable Broadside and Conical Beams

Abstract: A wideband, pattern-reconfigurable antenna is reported that is, for example, a good candidate for ceiling-mounted indoor wireless systems. Switchable linearly polarized broadside and conical radiation patterns are achieved by systematically integrating a wideband low-profile monopolar patch antenna with a wideband L-probe fed patch antenna. The monopolar patch acts as the ground for the L-probe fed patch, which is fed with a coaxial cable that replaces one shorting via of the monopolar patch to avoid deterioration of the conical-beam pattern. A simple switching feed network facilitates the pattern reconfigurability. A prototype was fabricated and tested. The measured results confirm the predicted wideband radiation performance. The operational impedance bandwidth, i.e., |S 11 | ≤ -10 dB, is obtained as the overlap of the bands associated with both pattern modalities. It is wide, from 2.25 to 2.85 GHz (23.5%). Switchable broadside and conical radiation patterns are observed across this entire operating bandwidth. The peak measured gain was 8.2 dBi for the broadside mode and 6.9 dBi for the conical mode. The overall profile of this antenna is 0.13λ 0 at its lowest operating frequency.

Compact, Highly Efficient, and Fully Flexible Circularly Polarized Antenna Enabled by Silver Nanowires for Wireless Body-Area Networks

Abstract: A compact and flexible circularly polarized (CP) wearable antenna is introduced for wireless body-area network systems at the 24 GHz industrial, scientific, and medical (ISM) band, which is implemented by employing a low-loss composite of polydimethylsiloxane (PDMS) and silver nanowires (AgNWs) The circularly polarized radiation is enabled by placing a planar linearly polarized loop monopole above a finite anisotropic artificial ground plane By truncating the anisotropic artificial ground plane to contain only 2 by 2 unit cells, an integrated antenna with a compact form factor of 041 λ 0 × 041 λ 0 × 0045 λ 0 is obtained, all while possessing an improved angular coverage of CP radiation A flexible prototype was fabricated and characterized, experimentally achieving S 11 <− 15 dB, an axial ratio of less than 3 dB, a gain of around 52 dBi, and a wide CP angular coverage in the targeted ISM band Furthermore, this antenna is compared to a conventional CP patch antenna of the same physical size, which is also comprised of the same PDMS and AgNW composite The results of this comparison reveal that the proposed antenna has much more stable performance under bending and human body loading, as well as a lower specific absorption rate In all, the demonstrated wearable antenna offers a compact, flexible, and robust solution which makes it a strong candidate for future integration into body-area networks that require efficient off-body communications

A Wide-Angle and Circularly Polarized Beam-Scanning Antenna Based on Microstrip Spoof Surface Plasmon Polariton Transmission Line

Abstract: In this letter, a wide-angle beam-scanning antenna with circular polarization (CP) characteristic is proposed. The antenna consists of two layers. Microstrip spoof surface plasmon polariton (SPP) is introduced on the bottom layer as a slow-wave feeding line. A series of circular patches are placed on the top layer as radiating elements. Simulated and measured results indicate that beam-scanning angle of the proposed antenna is improved and CP beam-scanning ability is obtained by introducing perturbation on the radiating elements. In the operating band of 11–15 GHz, measured scanning angle of the fabricated antenna is from –32° to +34°. The antenna axial ratio (AR) is below 3 dB at the corresponding beam direction, and gain is above 12.8 dBi over the whole band. It has potential applications in radar and wireless communication systems for simple structure, low-cost fabrication, wide beam-steering, and CP properties.

A compact double-sided MIMO antenna with an improved isolation for UWB applications

Abstract: This paper presents compact size 4 × 4 cm 2 MIMO antenna for UWB applications. The proposed antenna consists of four symmetric circular elements printed on low cost FR4 substrate with partial slotted ground plane. The two sides of the substrate are symmetric and each side is consisting of two radiators with the partial ground planes associated to the two other elements mounted on the other side. The two elements of the front side are orthogonal to the two other elements of the back side in order to increase the isolation between elements. For further reduction in the mutual coupling between elements, decoupling structures are presented in the top and bottom layers of the substrate. The simulated and measured results are investigated to study the effectiveness of the MIMO-UWB antenna. The results demonstrate the satisfactory performance of MIMO-UWB antenna, which has a return loss less than −10 dB from approximately 3.1 GHz to more than 11 GHz with an insertion loss lower than −20 dB through the achieved frequency band, and a correlation less than 0.002. Moreover, the proposed MIMO model exhibits a nearly omni-directional radiation pattern with almost constant gain of average value 3.28 dBi.

Mutual Coupling Reduction in Microstrip Patch Antenna Arrays Using Parallel Coupled-Line Resonators

Abstract: This letter presents the implementation of a pair of parallel coupled-line resonators (PCRs) for isolation enhancement in planar microstrip patch array antennas. Each PCR consists of three coupled lines separated by a small coupling distance. The attempted configuration provides band-reject characteristics at the design frequency of 3.5 GHz. Two such PCRs are replicated to provide higher order rejection that enhances the bandstop characteristics. The designed PCR is deployed in a two-element microstrip patch antenna array, and the mutual coupling characteristics are studied. The proposed PCR-based decoupling unit cell provides additional 12–26.2-dB coupling reduction with an enhancement of antenna gain up to 1.25 dB. The prototype antenna is fabricated, and the simulation results are validated using experimental measurements.

Reduction of Mutual Coupling Between Patch Antennas Using a Polarization-Conversion Isolator

Abstract: A novel approach to suppress mutual coupling (MC) between two patch antennas is presented in this letter. A parasitic isolator, which is printed between the two patches, controls the polarization of the coupling field to reduce the antenna coupling. Furthermore, a defected ground structure is employed to suppress the cross-polarization (XP) level. There exists a tradeoff between the MC reduction and XP improvement in this approach. As an example, a two-element patch array with an optimized isolator is fabricated and measured. The measured results show that, at the resonant frequency, the achieved isolation enhancement and XP level are 19.6 dB and $-$ 13.2 dB, respectively.

High-Gain and High-Aperture-Efficiency Cavity Resonator Antenna Using Metamaterial Superstrate

Abstract: In this letter, a high-gain, aperture-efficient cavity resonator antenna using metamaterial superstrate is reported. Highly reflective compact metamaterial surface resonating at 10.15 GHz with measured 3-dB bandwidth stopband characteristic of 4.10 GHz from 8.1 to 12.2 GHz is proposed. Material property of the metasurface is studied by using the free-space technique. Next, the metasurface is used as a superstrate to a patch antenna operating at 10.09 GHz, forming Fabry-Perot cavity. Gain enhancement of 11.85 dB in H-plane and 12.5 dB in E-plane with improved cross-polarization level and front-to-back ratio is observed. The prototype cavity antenna shows calculated gain of 16.35 dB achieving 92.42% of maximum gain due to effective aperture area in H-plane.

Wearable Antenna Integrated into Military Berets for Indoor/Outdoor Positioning System

Abstract: A wearable antenna integrated into a military beret for an indoor/outdoor positioning system is proposed. The antenna consists of a truncated patch and a circular ring patch with four conductive threads. The truncated patch antenna is designed for the Global Positioning System (GPS) L1 band for use in outdoor situations, and the circular ring patch antenna with four conductive threads operates at the TM41 higher-order resonance mode (915 MHz) with a monopole-like radiation characteristic for indoor positioning systems. The antenna is fabricated using textile materials and is integrated into a military beret. The effects of the antenna deformation due to the shape of the military beret and the effects of the human head are analyzed via both simulation and measurement. The simulated and measured 10-dB return-loss bandwidths of the antenna on the head phantom fully cover the 915-MHz industrial, science, and medical band and the 1.575-GHz GPS L1 band.

Wideband Circular-Polarization Reconfigurable Antenna With L-Shaped Feeding Probes

Abstract: A wideband circularly polarized reconfigurable patch antenna with L-shaped feeding probes is presented, which can generate unidirectional radiation performance that is switchable between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). To realize this property, an L-probe fed square patch antenna is chosen as the radiator. A compact reconfigurable feeding network is implemented to excite the patch and generate either LHCP or RHCP over a wide operating bandwidth. The proposed antenna achieves the desired radiation patterns and has excellent characteristics, including a wide bandwidth, a compact structure, and a low profile. Measured results exhibit approximately identical performance for both polarization modes. Wide impedance, 31.6% from 1.2 to 1.65 GHz, and axial-ratio, 20.8% from 1.29 to 1.59 GHz, bandwidths are obtained. The gain is very stable across the entire bandwidth with a 6.9-dBic peak value. The reported circular-polarization reconfigurable antenna can mitigate the polarization mismatching problem in multipath wireless environments, increase the channel capacity of the system, and enable polarization coding.

A New Technique to Design Circularly Polarized Microstrip Antenna by Fractal Defected Ground Structure

Abstract: A new technique to design single-feed circularly polarized (CP) microstrip antenna is proposed. The CP radiation is obtained by adjusting the dimension of the etched fractal defected ground structure (FDGS) in the ground plane. Parameter studies of the FDGS are given to illustrate the way to achieve CP radiation. The CP microstrip antennas with the second and third iterative FDGS are fabricated and measured. The measured 10-dB return-loss bandwidth of the CP microstrip antenna is about 30 MHz (1.558 to 1.588 GHz), while its 3-dB axial-ratio bandwidth is 6 MHz (1.572 to 1.578 GHz). The gain across the CP band is between 1.7 and 2.2 dBic.

Low-Mutual-Coupling 60-GHz MIMO Antenna System With Frequency Selective Surface Wall

Abstract: A new dielectric resonator antenna (DRA) for a millimeter-wave (mm-wave) multiple-input–multiple-output system is presented. Two approaches are exploited to reduce the mutual coupling between two antenna elements. First, a frequency selective surface (FSS) wall is inserted between the DRAs to reduce the free-space radiation. Then, two slots with different size acting like an $LC$ resonator are etched from the common ground plane of the structure to reduce the surface current. The designed FSS has a wideband characteristic from 40 to 70 GHz. The FSS is optimized for the desired frequency of 57–63 GHz. A high isolation of −30 dB is achieved when both FSS wall and slots are used. A prototype of the structure is fabricated and measured. The results give a low correlation coefficient ( $e$ –6) and a good agreement with simulation ones, indicating that the proposed antenna can provide spatial or pattern diversity to increase the data capacity of wireless communication systems at mm-wave bands.

Single-Layer Focusing Gradient Metasurface for Ultrathin Planar Lens Antenna Application

Abstract: A single-layer focusing gradient metasurface (MS) built by one element-group is proposed. The element-group is designed by well connecting the phase shift range of two similar single-layer elements under the condition of transmitting efficiencies over 0.7. The proposed MS can focus the propagating plane wave on a point and a patch antenna is placed at its focus to build a high-gain planar lens antenna. This lens antenna achieves pencil-shaped far-field radiation pattern with a simulation peak gain of 16.7 dB at 10 GHz. The single-layer structure makes it easy to fabricate the MS with low profile and satisfying performances. Finally, the MS and the patch antenna are fabricated, assembled, and measured. The measured results are in good agreement with the simulations.

Compact Wideband Circularly Polarized Patch Antenna Array Using Metasurface

Abstract: This letter proposes a compact wideband circularly polarized (CP) antenna array, which is a set of 2 × 2 metasurface-based CP patch antennas fed by a sequential-phase (SP) network. The single element is composed of a truncated corner square patch sandwiched between the ground plane and the metasurface of a lattice of 4 × 4 periodic metal plates. These metasurface-based antennas are incorporated with the SP network of a sequentially rotated series-parallel feed to achieve wideband operation. The radiation pattern and operational bandwidth in the high-frequency region were improved by reducing the spacing between the driven patches while maintaining the structure and overall size of the metasurface. The final design, with an overall size of 64 × 64 × 2.34 mm3 (approximately 1.26λo × 1.26λo × 0.046λo at 5.9 GHz), was fabricated and measured. The antenna array has a measured | $S_{11}$ | < −10-dB bandwidth of 4.40–8.00 GHz (58.06%), a 3-dB axial ratio bandwidth of 4.75–7.25 GHz (41.67%), a 3-dB gain bandwidth of 4.8–7.0 GHz (37.3%), and a peak gain of 12.08 dBic at 6.0 GHz. In addition, the antenna array yielded a broadside, left-hand CP radiation with a symmetrical profile, low sidelobe level, and high radiation efficiency.

Radial Uniform Circular Antenna Array for Dual-Mode OAM Communication

Abstract: A radial uniform circular array (UCA) is proposed for orbital angular momentum (OAM) generation and dual-mode communication based on a multilayer design. Theoretical derivation is presented for the demonstration of the OAM generation from radial UCAs. The UCA of single mode is realized by cascading an eight-dividing feeding network with equal magnitude and specific phases for each of two neighbor ports and eight microstrip antenna elements. Both the full-wave simulations and measurements of a final fabricated antenna array are carried out. From 5.72 to 5.95 GHz, the proposed antenna possesses good −15-dB bandwidths at the ±1 modes, and a very weak cross coupling (less than −24 dB) exists in this frequency band. The helical phase wavefronts are obtained, and the radiation patterns are presented. Moreover, the dual-mode multiplexing is achieved with isolations of different channels more than 19 dB in measurements.

A Wideband Circularly Polarized Conformal Endoscopic Antenna System for High-Speed Data Transfer

Abstract: In this paper, a conformal wideband circularly polarized (CP) antenna is presented for endoscopic capsule application over the 915-MHz Industrial, Scientific, and Medical (902–928 MHz) band. The thickness of the antenna is only 0.2 mm, which can be wrapped inside a capsule’s inner wall. By cutting meandered slots on the patch, using open-end slots on the ground, and utilizing two long arms, the proposed antenna obtains a significant size reduction. In the conformal form, the antenna volume measures only 66.7 mm3. A single-layer homogeneous muscle phantom box is used for the initial design and optimization with parametric studies. The effect of the internal components inside a capsule is discussed in analyzing the antenna’s performance and to realize a more practical scenario. In addition, a realistic human body model in a Remcom XFdtd simulation environment is considered to evaluate the antenna characteristics and CP purity, and to specify the specific absorption rate limit in different organs along the gastrointestinal tract. The performance of the proposed antenna is experimentally validated by using a minced pork muscle phantom and by using an American Society for Testing and Materials phantom immersed in a liquid solution. For measurements, a new technique applying a printed 3-D capsule is devised. From simulations and measurements, we found that the impedance bandwidth of the proposed antenna is more than 20% and with a maximum simulated axial ratio bandwidth of around 29.2% in homogeneous tissue. Finally, a wireless communication link at a data rate of 78 Mb/s is calculated by employing link-budget analysis.

A Low-Profile Reconfigurable Cavity-Backed Slot Antenna With Frequency, Polarization, and Radiation Pattern Agility

Abstract: A novel cavity-backed slot antenna, with the ability of reconfiguring the frequency, polarization, and radiation pattern, is presented. The reconfigurability is realized by electronically controlling the state of switches between two crossed slots etched on the surfaces of a substrate integrated waveguide cavity. The antenna is capable of simultaneously changing the radiation patterns between forward and backward directions, switching the polarization among two orthogonal linearly polarized (LP) and two orthogonal circularly polarized (CP) states, tuning between three frequency bands for LP states and between two frequency bands for CP states. A fully functional prototype is developed and tested, demonstrating the antenna with measured gains of approximately 4 dBi and stable unidirectional radiation patterns for all 20 states. In addition, the proposed design possesses a low profile of 0.01 free-space wavelength.

Design of filtering microstrip antenna array with reduced sidelobe level

Abstract: For the requirements of efficient integration and simple fabrication, a new codesign approach for a microstrip filter with an antenna array with reduced sidelobe level is introduced in this communication. The microstrip patch antennas and the stub-loaded resonators are used to illustrate the synthesis of a bandpass filtering antenna array. By controlling the coupling strength between the resonators, a uniform or nonuniform power divider network can be obtained. A nonuniform power division is used to reduce the sidelobe level. The equivalent lumped circuit model is developed and analyzed in detail. Two types of eight-element filtering antenna array with uniform and tapered power-distribution among the elements have been designed. Simulated and measured results provide a good verification for the theoretical concepts.

A Dual-Broadband, Dual-Polarized Base Station Antenna for 2G/3G/4G Applications

Abstract: A base station antenna with dual-broadband and dual-polarization characteristics is presented in this letter. The proposed antenna contains four parts: a lower-band element, an upper-band element, arc-shaped baffle plates, and a box-shaped reflector. The lower-band element consists of two pairs of dipoles with additional branches for bandwidth enhancement. The upper-band element embraces two crossed hollow dipoles and is nested inside the lower-band element. Four arc-shaped baffle plates are symmetrically arranged on the reflector for isolating the lower- and upper-band elements and improving the radiation performance of upper-band element. As a result, the antenna can achieve a bandwidth of 50.6% for the lower band and 48.2% for the upper band when the return loss is larger than 15 dB, fully covering the frequency ranges 704-960 and 1710-2690 MHz for 2G/3G/4G applications. Measured port isolation larger than 27.5 dB in both the lower and upper bands is also obtained. At last, an array that consists of two lower-band elements and five upper-band elements is discussed for giving an insight into the future array design.

A 28GHz CMOS direct conversion transceiver with packaged antenna arrays for 5G cellular system

Abstract: This paper describes a 28GHz CMOS direct conversion transceiver with packaged 2×4 patch antenna arrays for 5G communication. Test results show good RF performances of Rx NF 6.7dB, Maximum Tx EIRP 31.5dBm (1PA P out_sat =10.5dBm), LO integrated phase noise −37.8dBc (0.67°), Rx/Tx EVM around 2.2% (−33.1dB) at mid RF power, and well-fitted beam control capability.

Substrate Integrated Waveguide Cavity-Backed Slot Array Antenna Using High-Order Radiation Modes for Dual-Band Applications in $K$ -Band

Abstract: A novel compact dual-band cavity-backed substrate integrated waveguide (SIW) array antenna using high-order radiation modes has been proposed in this paper. The first high-order hybrid mode (superposition of TM310 and TM130) and the second high-order mode (TM320) of K-band in the SIW cavity are excited by an inductive window for dual-band application. The operation mechanism of high-order modes is analyzed and then verified through simulations by inserting metallic vias in different positions of the resonant SIW cavity. The designed subarray antenna has the advantages of high gain, high front-to-back ratio, and low cross-polarization level. To further validate the design idea, a dual-frequency band $2 \times 2$ array antenna has been fabricated and measured including reflection coefficients, realized gains, and radiation patterns. The measured results show that the 10-dB impedance bandwidths at resonant frequencies of 21 and 26 GHz are 800 MHz (3.7%) and 700 MHz (2.6%), and the realized gains at boresight direction are around 16 and 17.4 dBi, respectively. Moreover, the proposed array antenna also possesses both advantages of metallic cavity-backed antennas and planar patch antennas, such as low cost, easy fabrication with the printed circuit board technology, and integration with other planar circuits.

Miniaturized Circularly Polarized Square Slot Antenna With Enhanced Axial-Ratio Bandwidth Using an Antipodal Y-strip

Abstract: A novel single-fed, wideband, circularly polarized slot antenna is proposed and fabricated. Wideband circular polarization is obtained by introducing an antipodal Y-strip to a square slot antenna. The feedline is a U-shaped microstrip line that provides a wide impedance bandwidth. The overall size of the antenna is only 28 × 28 mm 2 (0.3 λ o × 0.3 λ o ). A prototype of the antenna is fabricated and tested. The measured bandwidths for the axial ratio (AR <; 3 dB) and relative impedance (|S 11 | <; -10 dB) are 41.3% (from 4.4 to 6.67 GHz) and 84% (from 3.25 to 8 GHz), respectively, and the antenna has a stable radiation pattern and a gain of greater than 3 dBi over the entire circular polarization frequency band.

Design of a Wideband Quad-Polarization Reconfigurable Patch Antenna Array Using a Stacked Structure

Abstract: In this paper, a wideband stacked patch antenna array composed of four linearly polarized antenna elements is proposed for the implementation of four polarization reconfigurable states, i.e., vertical linear polarization (LP), horizontal LP, left-hand circular polarization, and right-hand circular polarization. A double-layer structure, including a driven substrate integrated waveguide (SIW) cavity and four parasitic radiation patches, is used to develop the wideband antenna element. The parasitic radiation patches are excited by etching a ring slot on the top surface of the SIW cavity, which has two diagonal ports fed by grounded coplanar waveguide lines. A 180° phase-shifting is achieved for polarization reconfigurable applications by individually feeding the antenna element with the two diagonal ports. A prototype operating at 5.7 GHz is fabricated and tested for the demonstration of the polarization reconfigurable capability. The measured results show that both the 10-dB impedance bandwidths and the 3-dB axial ratio bandwidths are wider than 5.19–6.1 GHz for the linear and circular polarization states. The measured maximum gains of the antenna array are 9.85 dBic and 10.1 dBi for the circular polarization states and the LP states, respectively. Experimental results show good agreement with simulated results, which indicate a good performance of the proposed patch antenna array.