Artificial Magnetic Conductor Reflector Research Articles

Wideband Multi-polarization Reconfigurable Antenna based on Non-uniform Polarization Convert AMC Reflector

A novel design of wideband multi-polarization reconfigurable antenna is proposed, based on a non-uniform polarization convert artificial magnetic conductor (AMC) reflector. The proposed antenna consists of a radiator element and an AMC reflector. Firstly, a modified polarization convert AMC reflector is designed. The non-uniform AMC reflector causes an enhancement of 3 dB axial ratio (AR) performance. Secondly, a wideband linearly polarized monopole antenna is presented as the main radiator, utilizing the broadband characteristic of a C-shaped monopole. The polarization reconfigurability of the proposed antenna can be achieved by properly rotating the AMC reflector, which can be switched between linear polarization (LP), left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP). A prototype of the proposed antenna is fabricated and experimented with to validate the theoretical performance. The measured results show a -10 dB impedance bandwidth of 42.7% and 44.4% for LP and CP modes, respectively, and a 3 dB AR bandwidth of 20% for CP modes. In addition, the measured peak gain reaches 8 dBi/dBic. A good agreement is shown between the simulation and measurement, pointing to the good performance of the proposed antenna.

A wideband X‐band circularly polarized printed monopole antenna backed by AMC reflector for 5G/IoT CubeSat applications

AbstractThis letter presents a coplanar waveguide‐fed printed monopole antenna backed by an artificial magnetic conductor (AMC) reflector. The proposed monopole antenna achieves circular polarization by loading the monopole with a printed coil and using an asymmetric ground plane. In addition, the AMC increases the antenna gain while maintaining a wide axial ratio (AR) bandwidth. The unit cell of the AMC is based on a Minkowski‐like prefractal geometry. The antenna is fabricated and measured with a total size of 1.07 λ0 × 1.07 λ0 × 0.25 λ0 at the operating frequency of 8.5 GHz. The measured results show a wide −10 dB impedance bandwidth of 26.9% (7.12–9.38 GHz), a wide 3 dB AR bandwidth of 22.23% (8–9.89 GHz) as well as a peak gain of 8.3 dBi at 8.5 GHz. This is significantly better than comparable antennas in addition to this design being the smallest in size.

Miniaturized low‐profile ultra‐wideband circularly polarized archimedes spiral antenna backed by an AMC reflector

AbstractA low‐profile ultra‐wideband (UWB) circularly polarized antenna is proposed in the form of a planar Archimedes spiral structure backed by an artificial magnetic conductor (AMC). To expand its bandwidth and minimize its size, the antenna is loaded with resistors and a metal ring near the end of the spiral arms. At the same time, the bidirectional beam is transformed into a unidirectional beam using the phase compensation mechanism by introducing an AMC reflector. The antenna achieves −10 dB impedance bandwidth and 3 dB AR bandwidth in 0.7 ~ 10.2 GHz (174.3%), with a height of only 0.035 wavelengths at 0.7 GHz, which shows advantages over most similar designs. Finally, the antenna is fabricated and measured to prove its effectiveness.

Miniaturized High Gain Broadband 16‐Element MIMO Array Using Planar Artificial Magnetic Conductor With Enhanced Isolation for WLAN/WiMAX Applications

AbstractA low‐profile 16‐element printed dipole antenna (PDA) array backed by a planar artificial magnetic conductor (AMC) is introduced for multiple‐input multiple‐output (MIMO) wireless communications. The proposed 16‐element MIMO array loaded by a 13 × 13 AMC reflector with various polarized directions exhibits a low‐profile wideband structure, which includes the broad measured bandwidths from 4.25 to 7.25 GHz with increased gains (>8 dBi) and high efficiency. The high isolation between the 16 elements with diverse polarizations is larger than 27 dB and reaches 67 dB over the operating band for MIMO systems. The suggested PDA with a microstrip V‐shaped dipole excited by a V‐shaped microstrip feedline is used to expand the broad simulated band spanning 5.34–6.70 GHz (S11 ≤ −10 dB). Moreover, the suggested 13 × 13 planar fractal AMC reflector is loaded into the PDA array to exhibit a reflection coefficient, S11, of less than −10 dB across the band of 4.26–6.90 GHz for wireless local area network and worldwide interoperability for microwave access applications. The proposed design with AMC compared to the design without AMC exhibits a size reduction of 50.3%, increased gain up to 8.2 dBi, and excellent impedance matching with unidirectional radiation patterns. The novel AMC unit cell is realized based on the planar patch with inserted slots to operate at 6.10 GHz with an AMC band spanning 5.15–7.10 GHz (32%).

A tri-band flexible antenna based on tri-band AMC reflector for gain enhancement and SAR reduction

A tri-band wearable antenna fed by coplanar waveguide (CWP) with an artificial magnetic conductor (AMC) reflector is presented in this paper. The radiation patch consists of three open inverted triangles for multiband, and the ground is defected for better impedance matching The AMC unit is composed of three concentric nested regular octagonal rings. And to improve the performance of gain, the unit achieves three reflection zero phases at 1.8, 2.45 and 3.5 GHz corresponding to the three bands of the antenna. The proposed antenna based on AMC has been fabricated and measured. The working frequency bands are 1.34–1.67 GHz, 2.33–2.47 GHz and 3.55–3.7 GHz. The measured gain has increased by 3.4, 1.8, 4 dBi at 1.8, 2.45 and 3.5 GHz, respectively. The scenario that the antenna is placed on the human arm is also considered and experimented for wearable applications. The results are in good agreement with the simulation data and verify that the antenna has good robustness. When the antenna is conformal with the human tissue, the specific absorption rate (SAR) is calculated and reduced by about 99.8% after adding AMC reflector. Hence the proposed antenna has excellent wearable safety and is compatible with LTE 1800, WLAN, WiMAX communication systems.

A left hand circularly polarized (LHCP) wideband antenna array based on artificial magnetic conductor for Ka-band applications

A left-hand circularly polarized (LHCP) 2 × 2 array antenna is presented based on a modified artificial magnetic conductor (AMC) with improved gain and side lobe levels (SLLs). A single port modified sequentially rotated feed network combines the four corner truncated patch elements to achieve wider impedance bandwidth and axial ratio (A.R) bandwidth. The AMC array having wideband behavior consists of 9 × 9 unit cells with a single unit cell size of 2.4 × 2.4 mm2. The particular AMC-surrounded antenna array is simulated and manufactured using Rogers RT Duroid/5880 substrate and provides a wider bandwidth covering Ka-band (27 GHz to 32 GHz). The dimensions of the AMC integrated antenna array are 30 × 30 × 0.508 mm3. The proposed AMC shows in-phase reflection behaviors between (+ 90 and − 90) degree, from 27 GHz to 32 GHz. Combining the four-element antenna array with the AMC reflector improved the gain level of 0.7 dBi, 2.9 dBi, and 2.5 dBi at 28 GHz, 29 GHz, and 30 GHz, respectively. The simulated s-parameter (S11) and radiation patterns results are experimentally verified by measuring the prototype of the recommended antenna model. The proposed antenna array shows a stable gain variation and directive radiation patterns along 0o with low side lobe levels. Based on the performance, the proposed AMC-based antenna array can be an effective choice for the 3 U satellite applications in Ka-band.

Low‐profile wideband four‐element MIMO array using Giuseppe Peano AMC surface with improved efficiency and isolation for WLAN systems

AbstractA low profile four‐element multiple‐input multiple‐output (MIMO) array of printed dipole antenna (PDA) backed by second iteration of Giuseppe Peano fractal artificial magnetic conductor (AMC) is introduced for broadband wireless communications. First, a suggested PDA with a pair of microstrip E‐shaped dipoles excited by an E‐shaped microstrip feedline is used to expand the bandwidth in the range of 5.47–6.92 GHz (S11 ≤ −10 dB). Then, the suggested 4 × 4 Giuseppe Peano fractal AMC reflector is loaded into the PDA to exhibit −10 dB measured impedance bandwidth from 4.21 to 7.06 GHz (50.61%) for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The proposed four‐element MIMO array loaded by 6 × 6 AMC reflector with diverse polarizations of elements introduces a low profile wideband structure. The measured results of four elements include the broad bandwidths from 4.3 to 7.05 GHz with enhanced gains (more than 8 dBi) and high efficiencies. The high isolations between the four elements with diverse polarizations are obtained larger than 26.5 dB and they reach 66 dB over the operating bandwidth for MIMO systems. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 51.33%, enhanced radiation efficiency up to 94%, and excellent impedance matching with uni‐directional radiation patterns.

AMC-Loaded Low-Profile Broadband Printed 2×2 Array With Gain and Isolation Enhancement Using Equivalent Circuit Model for Wireless Systems

A 2×2 array of printed antenna loaded by planar Giuseppe Peano artificial magnetic conductor (AMC) is presented for vehicular wireless systems. The four-element of the proposed array by utilizing diverse polarized directions of the printed dipoles with a 5×5 AMC reflector achieves a wideband antenna with enhanced properties. It shows the measured S-parameters of the wide bandwidths from 3.30 to 6.02 GHz with increased stable gains and efficiencies (more than 90%) for all elements. Moreover, the appropriate isolation of greater than 30 dB between the elements is achieved. The proposed design of the printed dipoles includes T-shaped microstrip dipoles and a feedline system as a T-shape to broaden the bandwidth in 4.7-6.02 GHz (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> ≤ -10 dB). By utilizing the 3×3 Giuseppe Peano AMC reflector into the one element of the printed dipole, enhanced radiation efficiency and -10 dB measured bandwidth from 3.26 to 6.02 GHz (60%) is achieved for vehicular wireless systems. The proposed design with AMC with respect to the antenna without AMC indicates a reduced size of 70%, increased gain up to 8.4 dBi, and uni-directional radiation patterns. The new AMC unit cell is configured by the Giuseppe Peano design to resonate at 5.36 GHz in 4.27-6.34 GHz (39%). Finally, the suggested equivalent transmission line model of the 2×2 array with AMC surface is introduced with a suitable agreement between the results of reflection coefficients.

A metasurface-based electronically steerable compact antenna system with reconfigurable artificial magnetic conductor reflector elements.

Beyond 5G networks would require newer technologies to deliver a smarter network. In accordance with these requirements, an electronically steerable compact antenna system capable of beam-switching in the azimuth plane is proposed. The design uses a monopole antenna as the main radiator surrounded by metasurface-based electronically reconfigurable reflector elements designed for the sub-6GHz range. The reflector elements use a reconfigurable capacitively loaded loop (CLL) which can be electronically activated to work as an artificial magnetic conductor (AMC). The design offers a digitally controllable directional radiation pattern covering all 360° in the azimuth plane with a step-size of 30°, a directional gain of dBi and a high front-to-back lobe ratio (FBR) of dB. The compact and modular nature of the design combined with the use of commercial off-the-shelf (COTS) components and 3D-printing makes the design low-cost and easier to integrate with various internet of thing (IoT) applications.

Solar Cell Integrated Wearable Patch Antenna on Artificial Magnetic Conductor for On-Body and In-Body Communications

This paper presents a patch antenna on a jeans textile with an artificial magnetic conductor (AMC) structure stacked on a solar cell for wearable applications in the Industrial, Scientific, and Medical (ISM) band. Meanwhile, the loading of the AMC reflector increases the radiation efficiency and antenna gain and also results in a reduction in specific absorption rate levels. As examination cases, two textile antenna designs loaded on 7 × 8 patches of AMC plane with the ground plane of both fully copper conductor and partially copper aided with solar cells were fabricated and tested, presenting a strong agreement between simulation and measurement. Its measured impedance bandwidth is 13.79% (2.16 GHz–2.48 GHz) with good return loss and voltage standing wave ratio features in the operating band where it is being used. Besides being a source of electricity, the silicon solar cells are also used as a radio frequency ground plane for the AMC plane. They can produce363.08 mW.

Compact broadband circularly polarized slot antenna with artificial magnetic conductor reflector

A compact broadband circularly polarized slot antenna for Sub-6G applications is proposed in this article. It is composed of a broadband slot antenna exited by a Γ-shaped microstrip feedline and an artificial magnetic conductor (AMC) reflector with a wide in-phase reflection phase bandwidth. A unidirectional circularly polarized radiation is achieved by using the AMC reflector consisting of 6 × 6 modified Jerusalem cross unit cells. A prototype of the proposed antenna is fabricated. The impedance bandwidth and axial ratio bandwidth of the antenna is 40.78% (3.26–4.93 GHz) and 39.02% (3.3–4.9 GHz), respectively.

An Aperture-Coupled Stepped Dielectric Resonator UWB MIMO Antenna With AMC

In this letter, an aperture-coupled stepped dielectric resonator (DR) ultrawideband (UWB) multiple-input–multiple-output (MIMO) antenna (UMA) is presented. The proposed stepped DR resonates with quasi TE <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sup> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">δ11</sub> at 5.4 GHz and quasi TE <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sup> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1δ1</sub> mode at 6.4 GHz and merges with aperture resonating bands to achieve UWB. In the proposed orthogonal MIMO configuration, the stepped DR is able to improve the isolation in the higher frequency region and a modified neutralization line via a quarter wavelength square patch improves the isolation in the desired lower frequency region. The broadside radiating modes of the stepped DR and the dual artificial magnetic conductor (AMC) and PEC bands of the AMC reflector improves the gain and radiation characteristics. An improvement of 37.84% in gain stability within 2.3 dB variation (i.e., 4.2–6.5 dB) is achieved. The group delay of the UMA is more stable than the UWB antenna (UA). Thus, the problem of phase linearity is managed by multipath of the proposed UMA.

A multiband frequency reconfigurable and bifunctional metasurface

ABSTRACT A multiband, frequency reconfigurable, and bifunctional metasurface for simultaneous full-space control of Electromagnetic (EM) waves is proposed for wearable applications. The unit-cell structure contains concentric rectangular rings and empty substrate-integrated waveguides (SIWs) for miniaturisation. The miniaturised dimension of the Polydimethylsiloxane (PDMS) substrate is 18 × 18 × 1 mm3. Two varactor diodes are integrated for frequency switching operations by configuring the structure using bias voltage (forward/reverse) through the ground via the proposed surface resonates at 3.5,5.8,7.6 (On),8.1 (Off) GHz frequencies, which provide simultaneous bi-functionalities: artificial Magnetic Conductor (AMC) reflector/absorber in reflection and transmission space of operations, respectively. In reflection space, it acts as an AMC reflector by providing in-phase reflection with a radiation efficiency of >84% and unidirectional E-field patterns. However, the magnitude of absorbance is more than 96% in transmission, thereby simultaneously controlling full-space EM wave in normal incidence. The obtained simultaneous metasurface functionalities are investigated for different oblique angles of the transverse electric (TE) and transverse magnetic (TM) incident wave. The proposed surface is fabricated and experimentally validated. The features of the designed bifunctional metasurface provide a strategic platform for potential multifunctional wearable devices.

Gain enhancement of a wideband rectangular ring monopole millimeter‐wave antenna using artificial magnetic conductor structure

In this article, the design and development of an artificial magnetic conductor (AMC)-backed compact wideband rectangular ring monopole antenna with high gain is proposed for millimeter-wave (mmWave) applications. It is constructed through stacking a coplanar waveguide (CPW)-fed rectangular ring patch monopole antenna over a square modified AMC reflector surface of 5 × 5 periodic unit cells. Primarily, the ring monopole antenna of size 1.21λ0 × 1.21λ0 × 0.023λ0 (at 28 GHz) is designed and exhibits wide impedance bandwidth of 30.64% (25.98–35.38 GHz, 9.4 GHz), a peak gain of 4.86 dBi and front-to-back ratio (FBR) up to 5.2 dB. To enhance the radiation performance of the monopole antenna, a periodic lattice of 5 × 5 unit cells modified square AMC surface with a gap of 0.84λ0 is proposed and it functioned as reflector which enhances the peak gain of about ~77% and it contributes FBR up to 15 dB. Measured results of the modified square AMC-backed monopole antenna reveal a wide impedance bandwidth of 31.27% (25.90–35.50 GHz, 9.6 GHz), a peak gain of 8.59 dBi, and stable radiation characteristics.

Analysis of 2 × 2 MIMO array loaded by artificial magnetic conductor with improved gain, isolation, and bandwidth using equivalent transmission line model for indoor wireless base station

A low profile printed dipole antenna (PDA) backed by broadband Giuseppe Peano fractal artificial magnetic conductor (AMC) is introduced for wireless communications. First, a suggested PDA with a pair of microstrip dipoles excited by an E-shaped microstrip feedline is used to expand the bandwidth in the range of 5.96–7.04 GHz (S11 ≤ −10 dB). Then, the suggested Giuseppe Peano fractal AMC surface as a reflector of the antenna is inserted into the PDA to gain improved radiation efficiency. The PDA with the 6 × 6 Giuseppe Peano AMC array exhibits −10 dB measured impedance bandwidth of 4.95–7.05 GHz (35%) for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 38%, enhanced gain up to 8.2 dBi, and excellent impedance matching (at least −20 dB) with directional radiation patterns. The novel AMC unit cell is realized based on the Giuseppe Peano fractal patch to operate at 6.10 GHz with an AMC bandwidth of 5.15–7.10 GHz (32%). Besides, by loading 12 × 12 AMC reflector into the four-element array of PDA, low profile wideband structure with enhanced radiation properties are achieved. The measured results show the broad bandwidths of 5–7 GHz for all elements with enhanced gains and good isolations between the elements (more than 24 dB) for multiple-input multiple-output (MIMO) systems.

High‐isolated broadband eight‐element linear multi‐input multi‐output array over artificial magnetic surface for wireless and sub‐6 GHz 5G communications

SummaryA low‐profile eight‐element printed dipole antenna (PDA) array backed by broadband rhomboid artificial magnetic conductor (AMC) is introduced for wireless communication systems. By loading a 4 × 27 AMC reflector into the eight‐element array of PDA, a low‐profile wideband structure with enhanced radiation properties is achieved. The measured S parameters show the broad bandwidth from 4.75 to 7.05 GHz in C‐band with enhanced gains of eight elements (more than 8 dBi) and the suitable isolation between the array elements of more than 23 dB for multi‐input multi‐output (MIMO) systems. The suggested PDA with a pair of the microstrip meandered folded poles excited by an E‐shaped microstrip feedline expands the bandwidth in the range of 5.85–6.95 GHz (S11 ≤ −10 dB). The novel AMC unit cell is realized based on the recognized method as rhomboid coupled parasitic patches. The rhomboid AMC design operates at 6.26 GHz with an AMC bandwidth of 5.20–7.24 GHz (32.8%). Then, the suggested rhomboid AMC surface as a reflector of the antenna is inserted into the PDA to exhibit −10 dB measured impedance bandwidth from 4.94 to 6.93 GHz (more than 33%) for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 34%, enhanced gain up to 8 dBi, and excellent impedance matching (at least −20 dB) with directional radiation patterns.

Radiation Properties Improvement of 1 × 4 Array of Wideband Printed Antenna Supported by AMC Surface for Vehicular MIMO Systems

AbstractA 1 × 4 array of printed dipole antenna (PDA) with a broadband rhomboid artificial magnetic conductor (AMC) is introduced. A suggested PDA using a pair of microstrip dipoles with unequal arms excited by a T‐shaped microstrip feedline expands the bandwidth in the measured range of 5.27–6.74 GHz. Then, the suggested 3 × 3 AMC reflector is inserted into the PDA to exhibit −10 dB measured impedance bandwidth from 4.20 to 7.11 GHz for WLAN and WiMAX applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 46.72%, enhanced gain up to 8.4 dBi, and excellent impedance matching with unidirectional radiation patterns. The novel AMC unit cell operates at 6.20 GHz with an AMC bandwidth of 5.09–7.21 GHz. Also, by loading a 3 × 8 AMC periodic array on a FR4 substrate with 3 mm thickness underneath the four‐element array of PDA with a gap distance of 3 mm, a low‐profile wideband structure with enhanced radiation properties is achieved. The measured S‐parameters show the broad bandwidth from 4.26 to 7.28 GHz with enhanced gains and efficiencies of all elements. Besides, the suitable isolation between the array elements of more than 30 dB for multiple‐input multiple‐output (MIMO) systems is achieved by applying various polarized directions of PDAs and loading the 3 × 8 periodic AMC reflector. Finally, the proposed MIMO design introduces remarkable advantages of good size reduction and bandwidth enhancement, low‐profile antenna with high stable gain, high efficiency and large isolation, and unidirectional radiation patterns with reduced backside direction.

Design of a wideband patch antenna and performance enhancement using an AMC reflector surface for on-body communication at 2.45 GHz

ABSTRACT Wireless biotelemetry enables the formation of communication link from living body to an external monitoring device. Isolation of near field electromagnetic (EM) waves from body tissue, and wide bandwidth to avoid frequency detuning in different biological environments are the important parameters of on-body antennas. In this paper, a conformal defected ground patch antenna with artificial magnetic conductor (AMC) is introduced for on-body communication. Initially, a quarter wave wide band antenna with a shorting pin is designed to operate at 2.45 GHz. It resonates effectively on body tissue but most of the near field EM radiations are absorbed by tissue. Poor radiation efficiency of 10% and high specific absorption rate (SAR) value of 7.73 W/Kg were obtained. Thus, to reduce the effect of tissue loading on antenna performance an AMC-based structure is added. Better impedance matching, high efficiency (65%) and directivity (7.3 dBi) is achieved with AMC structure. Furthermore, unidirectional radiation pattern with SAR value of 1.43W/Kg is attained. Wide bandwidth of 600 MHz on phantom enables the antenna to withstand frequency detuning effect due to body postures and movements. Antenna robustness is analysed by bending the structure at different radii along X-axis and Y-axis.

A low‐profile dual‐band dual‐polarized tightly spaced antenna array with artificial magnetic conductor surface for 5G micro base station application

A novel low-profile dual-band dual-polarized tightly spaced antenna array with artificial magnetic conductor (AMC) surface for 5G micro base station application is proposed in this paper. The main radiating element is a pair of crossed annular dipoles, excited with two different resonant modes in orthogonal arms. The radiator is backed by an additional dual-band AMC reflector located 0.03 λ0 below. Four such elements are then tightly spaced to form an antenna array. By replacing the four interior AMC patches with an S-shaped patch, the strong coupling at the lower band is successfully mitigated. The final results show that the dual-band array has an impedance bandwidth of 13.8% (2.44–2.80 GHz) and 6% (4.75–5.03 GHz), covering the sub-6GHz band of China Mobile. The antenna's peak realized gain is 10 dBi at the lower band and 13.7 dBi at the upper band, making it a good candidate for 5G micro base stations.

Compact Shared-Aperture Dual-Band Dual-Polarized Array Using Filtering Slot Antenna and Dual-Function Metasurface

This article presents a shared-aperture dual-band dual-polarized antenna array for fifth-generation (5G) mobile communication. Within one radiating aperture, four higher band (HB) patch antenna elements are placed over the lower band (LB) full-wavelength slot antenna. The proposed array is miniaturized by bending the ground plane of the slot antenna. Suppression of cross-band mutual coupling and scattering is achieved by using the filtering performance of the slot antenna and a dual-function metasurface. The filtering performance of the slot antenna is realized using coupled microstrip lines inside the radiating slot and open-ended stubs on the feeding lines. The dual-function metasurface operates as an artificial magnetic conductor reflector in the LB and bandpass frequency-selective surface in the HB. By placing the dual-function metasurface behind the slot antenna, the radiation of the slot antenna is enhanced in the LB but not HB, and the negative effect of its HB scattering on the HB antennas is reduced. The working mechanism is explained in detail. The measured and simulated results demonstrate that the proposed array has stable radiation patterns in the bands of 0.69–0.96 and 3.4–3.7 GHz with a high cross-band isolation of over 32 dB and is more compact than the previous works.