High Gain Radiation Research Articles

Design of Low Profile ATFSS and Antenna With In-Band and Out-of-Band RCS Reduction

Stealth is a very important property for antennas, not only in-band stealth, but out-of-band stealth will also greatly affect the overall stealth of antennas. Thus, a novel low-profile absorbing/transmitting integrated frequency selective surface (ATFSS) is proposed in this article, and then an antenna with in-band and out-of-band radar cross section (RCS) reduction is designed by combining it with an array antenna with integrated radiation and scattering. The profile height of the novel ATFSS is only 3.6 mm, and the gain of the in-band and out-of-band RCS reduced antenna is greater than 17.5 dBi and its insert loss is less than 1 dB in 8.5–10 GHz. Meanwhile, the antenna can achieve significant RCS reduction in the out-of-band of 4.8–8.5, 11.2–15.1 GHz, and in the in-band of 8.5–10.5 GHz. Excellent agreement is obtained between simulation and measurement for the in-band and out-of-band RCS reduced antenna. Such a method not only can significantly reduce the profile height of the traditional ATFSS, broaden the low detectable bandwidth and enhance the invisibility of the antenna, but also maintain the high gain radiation characteristics of the antenna, which has important practical application value.

Highly efficient 4‐port self‐decoupled multiple‐input multiple‐output antenna pairs operating in n46 band for 5G smartphone applications

A highly efficient self-isolated multiple-input multiple-output (MIMO) antenna system functioning in the n46 5G NR band (5.15–5.925 GHz) for smartphone implementation is discussed in this paper. The system is made up of two blocks of vertically printed antenna pairs, placed at the exact center of the side frames of the smartphone. Each block comprises of a self-isolated antenna pair with two inverted L-shaped radiators facing each other, a T-shaped isolating element, and a U-shaped structure placed at the back of the radiators, and is attached to the ground plane. A simple coaxial feeding structure is deployed to excite the L-shaped radiators. The T-shaped structure placed between the two radiators has a crucial role in minimizing the mutual coupling between the two radiators, and its arm serves as a radiator. The self-isolated antenna pair functions from 5.10 to 5.98 GHz, covering the entire n46 band (5.15–5.925 GHz) with over −16.8 dB isolation in the complete operating bandwidth. The parametric investigation of some ideal parameters and the antenna pair evolution stages to obtain the final structure is examined for a superior understanding of the functioning of the proposed MIMO smartphone system. The proposed self-decoupled antenna pair MIMO system operates with a very high radiation efficiency and gain in the complete operating bandwidth, with radiating efficiency, total efficiency, and peak gain greater than 92%, 85%, and 6 dB respectively. The lowest obtained envelope correlation coefficient (ECC) value is 0.025 between the two elements in the antenna pair, which is very low when compared with the ideal value of 0.5. Various other parameters like channel capacity loss (CCL), mean effective gain (MEG), total active reflection coefficient (TARC), and diversity gain (DG) of the proposed system are also calculated and examined with the experimental results to study the diversity performance of the proposed MIMO smartphone system. A prototype of the proposed 4-port MIMO smartphone system is fabricated and various parameters are examined. The coherence between the measured and the experimental outcomes stipulates that the proposed system is a capable contender for application in the upcoming 5G handheld devices.

A High Gain Embedded Helix and Dielectric Rod Antenna with Low Side Lobe Levels for IoT Applications.

In this paper, a novel embedded helix dielectric rod antenna is presented for high gain radiation with circular polarization (CP) and low side lobe levels for IoT Applications. Different from the conventional dielectric rod antennas, this proposed antenna is an integrated structure that combines the advantages of the helix and dielectric rod antennas. The presented antenna mainly consists of three parts: a tapered helix as primary feeding for CP, a dielectric rod with printed loops embedded for higher directivity, and a dielectric rod end for improving the gain further. After studying and analyzing the working principles of each part, an optimum design operating at 8–9.7 GHz is carried out as an example. A prototype is also fabricated and tested. The measured results show that the prototype can provide 18.41 dB maximum gain within the length of 7.7 λ. The side lobe level is below −20 dB, and the axial ratio is better than 1.14 dB in the whole frequency band. Compared with the traditional helix antenna and dielectric rod antenna with the same electric length, the presented antenna has a higher gain with a lower side lobe level and with good polarization purity.

Multifunctional Coding-Feeding Metasurface Based on Phase Manipulation.

Multiple functionalities on a shared aperture are crucial for metasurfaces (MSs) in many applications. In this paper, we propose a coding-feeding metasurface (CFMS) with the multiple functions of high-gain radiation, orbital angular momentum (OAM) generation, and radar cross-section (RCS) reduction based on phase manipulation. The unit cell of the CFMS is composed of a rectangular emission patch and two quasi-Minkowski patches for reflective phase manipulation, which are on a shared aperture. The high-gain radiation and multiple modes of ±1, ±2, and ±3 OAM generation were realized by rationally setting the elements and the phase of their excitation. The CFMS presents a broadband RCS reduction of 8 dB from 3.18 GHz to 7.56 GHz for y-polarization and dual-band RCS reduction for x-polarization based on phase interference. To validate the concept of the CFMS, a prototype was fabricated and measured. The results of the measurement agree well with the simulation. A CFMS with the advantages of light weight and low profile has potential application in detection and wireless communication systems for stealth aircraft.

Millimeter-Wave High-Efficiency Double-Layer Transmitarray Antenna Using Miniaturized Dual-Polarized Elements

A high-efficiency wideband double-layer transmitarray antenna (TA) using miniaturized array elements is proposed in the study for millimeter-wave (mm-Wave) applications. The transmitarray consists of 484 dual-polarized elements. Each element is composed of only two layers of identical modified Jerusalem crosses printed on a dielectric substrate. Additional stubs are used for size reduction, leading to a compact size with a periodicity of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.44 \lambda _{0}$ </tex-math></inline-formula> . It contributes to a high aperture efficiency for the proposed TA. TA is designed, fabricated, and measured. It achieves a peak gain of 28.67 dBi at 31 GHz and a high aperture efficiency of 44%–61.3% within the 1 dB gain bandwidth, which is 10.3% (29.5–32.7 GHz) in the measurement. The proposed dual-polarized double-layer TA demonstrates simplified design complexity, reduced thickness and mass, and lower cost compared with the conventional TAs. It also exhibits high radiation gain and high aperture efficiency.

Dual-Frequency Microstrip Leaky-Wave Antenna for High-Gain Broadside Radiation

This article presents a resonator-fed dual-frequency dual-mode bidirectional leaky-wave antenna to provide attractive high-gain broadside radiation at dual desired frequencies. First, by analyzing the dispersion diagrams of the first (EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ) and third (EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) higher order modes of a microstrip line, it is theoretically verified that these two modes can both be suitably employed for bidirectional leaky-wave antenna design. In addition, it is also determined that the ratio between these two operation frequencies can be handily controlled by appropriately loading periodical shorting pins along the nodal lines of the EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> modal field. As such, the dual-frequency operation principle is thoroughly investigated and determined. Afterward, to effectively excite the desired modes and suppress any unwanted modes of the microstrip line, a dual-frequency resonant-fed strategy is adopted. More specifically, the introduced feeding resonator is first fed by a pair of differential probes, and then, the microstrip EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> modes are excited through the coupling gap. In this way, the desired pure EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> modes are successfully excited. As an example, a dual-frequency bidirectional microstrip leaky-wave antenna is designed to work at 3.6 and 4.9 GHz, and its prototype is simulated, fabricated, and tested. The obtained far-field radiation patterns from simulations and measurements show a reasonable agreement, and the concerned high-gain radiation at the broadside is well achieved at both frequencies.

A Wideband High-Gain Microstrip Array Antenna Integrated with Frequency-Selective Surface for Sub-6 GHz 5G Applications.

This paper presents a wideband and high-gain rectangular microstrip array antenna with a new frequency-selective surface (FSS) designed as a reflector for the sub-6 5G applications. The proposed antenna is designed to meet the US Federal Communications Commission (FCC) standard for 5G in the mid-band (3.5–5 GHz) applications. The designed antenna configuration consists of 1 × 4 rectangular microstrip array antenna with an FSS reflector to produce a semi-stable high radiation gain. The modeled FSS delivered a wide stopband transmission coefficient from 3.3 to 5.6 GHz and promised a linearly declining phase over the mid-band frequencies. An equivalent circuit (EC) model is additionally performed to verify the transmission coefficient of the proposed FSS structure for wideband signal propagation. A low-cost FR-4 substrate material was used to fabricate the antenna prototype. The proposed wideband array antenna with an FSS reflector attained a bandwidth of 2.3 GHz within the operating frequency range of 3.5–5.8 GHz, with a fractional bandwidth of 51.12%. A high gain of 12.4 dBi was obtained at 4.1 GHz with an improvement of 4.4 dBi compared to the antenna alone. The gain variation was only 1.0 dBi during the entire mid-band. The total dimension of the fabricated antenna prototype is 10.32 λo × 4.25 λo ×1.295 λo at a resonance frequency of 4.5 GHz. These results make the presented antenna appropriate for 5G sub-6 GHz applications.

Flexible compact system for wearable health monitoring applications

In this modern world, the need for compact, lightweight, and flexible devices to modernize and monitor the health in busy day-to-day life is increasing drastically. In connection to this, a flexible and compact antenna using a flexible PDMS substrate is proposed in this research with high radiation efficiency and gain. These antennas can be integrated with wearable sensors to continuously keep track the health and send data remotely. The flexible antenna comprises a rectangular patch embedded in a flexible PDMS substrate. The flexible PDMS substrate has high thermal stability, high tensile strength, and low permeability to oxygen and water vapor which will increase the lifetime and stability of the antenna. The flexible antenna for Industrial, Scientific, and Medical (ISM) band of 2.45 GHz is designed and analyzed by performing a comprehensive parametric study. The performance of the flexible antenna was evaluated in terms of return loss, radiation pattern polar plots, gain, and VSWR. The fabricated antenna has a return loss of -23.34 dB at a center frequency of 2.45 GHz. The fabricated antenna is omnidirectional, which covers a broad range in both E-plane and H-plane. The advantages such as lightweight, low cost, high stability and flexible nature of this antenna will have potential applications in biomedical, military, and defense applications.

Tunable terahertz filter/antenna-sensor using graphene-based metamaterials

In this paper, a novel tunable graphene-based bandstop filter/antenna-sensor is presented. This structure is an integrated module that can be used to combine filtering and high-gain radiation performance. The initial design of the unit cell consists of four U-shaped stubs loaded, resembling the arms of a ring and a sensing layer in the substrate. The reflection and transmission spectra are obtained for various graphene’s chemical potentials and refractive index of sensing layer (Ns) of structure in the range of 1.3–1.6 THz. The proposed structure exhibits the attributes of both dual-band filter and single-band antenna-sensor. The conductivity of graphene and its structural parameters are studied to optimize the component performance. In filtering mode, the first bandstop is from 1.23 to 1.6 THz equal to 26% of fractional bandwidth (FBW) at 1.415 THz. The second stopband is centered at 3.12 THz with FBW of 14% for Ns = 1.6 and 0.6 eV chemical potential. In the antenna mode, a single band of the antenna-sensor is centered at 1.95 THz for the same Ns and same chemical potential. It is shown that a sensitivity of 0.145 THz/RIU is achieved at Ns = 1.5 and chemical potential of 0.6 eV. Additionally, the performance of the proposed filter/antenna-sensor module is investigated for different wave polarizations and oblique angles.

Dual-Band Antenna Hybridizing Folded Transmitarray and Folded Reflectarray

This communication proposes a dual-band antenna hybridizing a folded reflectarray antenna (FRA) and a folded transmitarray antenna (FTA). First, a polarization-rotation transmitarray is designed based on a new Fabry–Perot (FP)-liked phasing element. Unlike its counterparts, this new FP-liked phasing element twists the polarization of electromagnetic (EM) waves and provides sufficient phase tuning range only in the operating band of FTA. In the meantime, in the band of FRA, the transmitarray acts as the polarizing grid, which reflects one polarization while allowing the orthogonally polarized one to pass without affecting its polarization and phase. Second, a polarization-rotation-ground-integrated (PRGI) reflectarray is designed. The reflectarray collimates the EM wave in the band of FRA and twists its polarization by 90°, forming the folded reflectarray. Meanwhile, it also twists the polarization of the EM wave in the band of FTA. By hybridizing the FTA and FRA sharing the same aperture, the proposed design achieves dual-band high-gain radiation. To the best of our knowledge, this is the first time that the FRA and FTA are combined to form a shared aperture antenna, which inherits the advantages of both FRA and FTA, such as high gain, low profile, and reduced blockage effect of the feed. An antenna prototype is fabricated and measured to verify the idea.

Metasurface-based electromagnetic structure for electromagnetic absorption and radiation application

AbstractIn this paper, a metasurface (MS)-based multi-functional electromagnetic (EM) structure is proposed to realize its two different applications, namely absorption and radiation. The proposed structure is based on periodic arrays of disk-shaped metallic patches and split rings with four embedded lumped resistors. The metallic vias are inserted from top to bottom to connect the disk-shaped patches with a feeding network designed on the bottom layer where two p-i-n switches are embedded in the feeding network to alter the different functions of the proposed structure. For free space incident plan wave, the designed structure works as an absorber when the p-i-n switches are switched OFF. The absorber operates over a frequency band from 6.2 GHz to 8.2 GHz and unchanged over an incident angle from 0° to 30° for both TE and TM polarized incident waves. The same structure also works as a low scattering and high gain radiator when the p-i-n switches are turned ON and radiate within absorbing frequency band, i.e. from 7.5 to 8.0 GHz. The designed structure is fabricated and experimentally verified for EM absorption and radiation applications.

Radiation-Scattering–Integrated Design of Multi-Functional Metasurfaces Based on Antenna-Embedded Substrates

The integration of the metasurface and antenna has brought new vitality to function integration and performance improvement for metasurfaces. In this study, we propose a radiation-scattering–integrated (RSI) design method of functional metasurfaces by incorporating antenna radiators into the substrates. The antenna radiators can also be considered as a band-stop frequency selective surface (FSS) embedded within the dielectric substrate, which adds up to the degree of freedom (DOF) in tailoring electromagnetic (EM) properties of the substrate. In this way, not only radiation function is added to the metasurfaces but also the original scattering-manipulation function is augmented. As an example, we apply this method to the design of a metasurface that can achieve a high radiation gain in-band and low-RCS out-of-band simultaneously. An antenna array was first designed, which uses circular patches as the radiators. Then, the antenna array was used as the substrate of a typical polarization conversion (PC) metasurface. The circular patch lies between the ground plane and the PC meta-atom, providing optimal electrical substrate thickness for PC at two separate bands. By adjusting structural parameters, the operating band of the antenna array can be made to lie in between the two PC bands. In this way, the metasurface can simultaneously possess high-gain radiation function in-band and high-efficiency PC function for RCS reduction out-of-band. A prototype was fabricated and measured. Both the simulated and measured results show that the metasurface can achieve satisfactory radiation gain in-band and significant RCS reduction out of band. This work provides an alternative method of designing multi-functional metasurfaces, which may find applications in smart skins and others.

Length-Irrelevant Dual-Polarized Antenna Based on Antiphase Epsilon-Near-Zero Mode

In this communication, a novel dual-polarized (DP) epsilon-near-zero (ENZ) antenna is proposed with its operating frequencies independent of lengths for both polarizations. To obtain a DP implementation of ENZ antenna, an antiphase ENZ (AP-ENZ) mode is used based on a slot-fed substrate-integrated waveguide (SIW) antenna at its cutoff frequency, in which the electric field presents a sign-function-like distribution, presenting a fixed operating frequency independent on length. The proposed DP length-irrelevant antenna design is composed of a cross-shaped SIW operating on two orthogonal AP-ENZ modes, which are excited by a cavity-backed cross-shaped slot with good port isolation. The SIW lengths for both polarizations can be tuned independently without disturbing the operation frequency with controllable radiation patterns. To be specific, we study two cases of different lengths where sidelobe elimination and high gain radiation are realized, respectively. To verify this design, two antenna prototypes Ant. 1 and Ant. 2 are fabricated and tested, exhibiting agreements between simulation and experiment. The proposed Ant. 1 presents no sidelobes at 2.42 GHz while Ant. 2 shows a high gain of 10.56 dBi from 2.45 to 2.55 GHz. The proposed design method enables antennas with a variety of radiation patterns to be designed at a fixed frequency and both symmetric and asymmetric patterns for DP antennas. It also inspires the design of a flexible antenna with unchanged operating frequency when folded in both dimensions.

Compact Patch Antenna Array With Fan-Beam Characteristics for Radar Application

In this paper, a compact 1×4 patch array antenna with a fan-beam radiation pattern is introduced for use in 3.5 GHz band applications. The proposed antenna consists of a planar two-layer printed structure so that the radiation elements and feeding network are located in the upper and lower layers respectively. In this way, the antenna has very compact dimensions while achieving a high radiation gain. Using a reflector plane under the antenna has improved the radiation pattern and decreased the antenna back radiation. The fabricated array antenna has an impedance bandwidth of 3.35-3.75 GHz (11.27%), a maximum realized gain of 10.91 dBi, and half power beamwidths (HPBWs) of 23.86° and 85.44° on the H- and E-panels, respectively. The overall dimensions of the antenna are 209×32.3×3.708 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> with a 250×50 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> conductive reflector at a distance of λ/4 from the antenna, and the theoretical and practical results show a good agreement with each other. The presented antenna is suitable for 5G systems and radar applications in the 3.5 GHz frequency band.

FSS-embedded substrates: a facile method of augmenting functions of metasurfaces

Metasurfaces, usually composed of 2D arrays of sub-wavelength metallic patterns (also called meta-atoms), have provided unprecedented freedoms for manipulating electromagnetic (EM) waves. In practice, meta-atoms are usually patterned on a certain substrate, so the EM properties of substrates directly affect the performances of metasurfaces. Therefore, it is desirable that the substrates can also be engineered with a high degree of freedom (DOF) so as to augment the functions of the metasurfaces. With this in mind, in this paper, we propose a method of designing functional metasurfaces by engineering the EM properties of substrates. By embedding frequency selective surface (FSS) within dielectric substrates, the electrical thickness of the substrates can be tailored according to the specific operating frequencies. In this way, functions of the metasurfaces can be augmented, either by better performances or by additional functions. As an example, we designed a multi-functional metasurface and applied it to a low-RCS reflector antenna. A circular patch was inserted into the dielectric substrate beneath the meta-atom. Due to the band-stop property of the metallic patch, two polarization conversion (PC) bands, together with a polarization-keeping band in between them, were created. Using this meta-atom, the metasurface is further designed, which can simultaneously achieve in-band focusing and out-of-band PC. A prototype was fabricated and measured. Both the simulated and measured results verified the good performance. Empowered by the metasurface, the reflector antenna achieved high radiation gain in band and significant RCS reduction out of band. This work provides a facile method of designing multi-functional metasurfaces and can be readily extended to terahertz, optical and other frequency regimes.

Dual-Band Dual-Mode Patch Antenna With High-Gain and Wide-Beam Radiations in Two Respective Bands

In this article, a novel dual-band dual-mode (DBDM) patch antenna is proposed with flexible radiation coverage and a simple structure. Distinct radiation properties with high-gain in the lower band and wide-beam in the upper band could be attained under a small frequency ratio and a single element. The working principle of the wide-beam radiation is, for the first time, proposed and theoretically analyzed based on the electric current calculation, providing a good insightful understanding of the radiation of the inverse currents. The high-gain radiation in the lower band is realized by introducing the shunt inductive effect while maintaining a negligible influence on the upper band. In terms of realization, a pair of stubs and shorting pins are properly loaded on a square patch to achieve the conditions required in the theoretical analysis. It indicates that the proposed method could be easily achieved with the simple structure of a single layer and a single element. Additionally, further discussion on the size reduction of the patch is provided with good cross-polarization. Two prototypes are finally designed, fabricated, and tested. The simulated and measured results exhibit good agreement with each other, certifying the validity of the proposed method. All these attractive merits, such as flexible coverage with high-gain and wide-beam radiations, simple structure with a single element, small achievable frequency ratio, and low profile, demonstrate that the proposed antenna could be a good potential candidate in the modern wireless systems.

A compact CPW-fed monopole antenna for multi-band application

Abstract A compact coplanar waveguide-fed monopole antenna is presented in this paper. The proposed antenna is composed of three monopole branches. In order to achieve the miniaturization, the longest branch was bent. The antenna is printed on an FR4 dielectric substrate, having a compact size of 0.144λ0 × 0.105λ0 × 0.003λ0 at its lowest resonant frequency of 900 MHz. The multiband antenna covers five frequency bands: 820–990 MHz, 1.87–2.08 GHz, 2.37–2.93 GHz, 3.98–4.27 GHz, and 5.47–8.9 GHz, which covers the entire radio frequency identification bands (860–960 MHz, 2.4–2.48 GHz, and 5.725–5.875 GHz), Global System for Mobile Communications (GSM) bands (890–960 MHz and 1.850–1.990 GHz), WLAN bands (2.4–2.484 GHz and 5.725–5.825 GHz), WiMAX band (2.5–2.69 GHz), X-band satellite communication systems (7.25–7.75 GHz and 7.9–8.4 GHz), and sub 6 GHz in 5G mobile communication system (3.3–4.2 GHz and 4.4–5.0 GHz). Also, the antenna has good radiation characteristics in the operating band, which is nearly omnidirectional. Both the simulated and experimental results are presented and compared and a good agreement is established. The proposed antenna operates in five frequency bands with high gain and good radiation characteristics, which make it a suitable candidate in terminal devices with multiple communication standards.

A broadband reconfigurable antenna with parasitic water radiation Array

This article introduces a wideband pattern reconfigurable antenna made of seawater. A special funnel-shaped metal structure is used for feeding to increase the bandwidth of the antenna. The antenna-design refers the electronically steerable parasitic array radiator antenna principle, and arc-shaped water columns are introduced around the seawater monopole antenna to operate as parasitic passive oscillators. These parasitic elements turn the omnidirectional antenna into a directional antenna. The proposed antenna has more than one mode. When the number of parasitic elements is 2, 3, and 4, it respectively corresponds to three different working modes: dual-beam radiation, wide-angle radiation, and directional high-gain radiation. And in all these three modes, changing the position of the parasitic elements can achieve 360° beam-sweeping in the 1.66 ~ 2.78 GHz. A prototype is fabricated and verified, and the experimental results are in good agreement with the simulated results. The antenna is filled with seawater when in use, and the weight can be reduced by draining the seawater when not in use. There is great application potential in the field of maritime communications.

Novel design of a triple band PIFA antenna by using a binary genetic algorithm

In this study, we propose a miniature triple band PIFA antenna (planar inverted-F antenna) composed of uniform semi-patches for LTE2600/WLAN/WIMAX/HIPERLAN-2 applications. The binary genetic algorithm determines the shape of the antenna’s radiating plate to achieve multiband operation with good performance. The simulated results reveal that the proposed antenna has attained three bandwidths ( $$S_{11} <-\,10\mathrm{dB}$$ ). The first bandwidth is from 2.5 to 3.07 GHz with resonant frequency at 2.80 GHz. The second bandwidth takes the range from 3.79 to 3.99 GHz with an operating frequency at 3.89 GHz. The third bandwidth is from 5.64 to 5.94 GHz with resonance at 5.78 GHz. All three resonant frequencies demonstrate good impedance matching with high radiation efficiency and gain. The PIFA antenna design is constructed of two FR4 epoxy substrates and has dimensions of $$15 \times 30 \times 3.8\,\mathrm{mm}^3$$ . The proposed multiband PIFA antenna exhibits good performance with small size, making it suitable for several wireless systems applications.

Dual-band magneto-electric dipole antenna with high-gain for base-station applications

The paper presents the results of a novel high-gain dual-band magneto-electric dipole (MED) antenna. The antenna comprises two pairs of horizontal metal plates of different heights that are excited by a Γ-shaped feedline structure. The antenna is entirely made of metal plates. Compared to traditional MED antennas, the proposed design exhibits dual-band operation with a higher radiation gain whose frequency ratio can be modified by simply adjusting the heights of the two magneto-electric dipole segments. This feature is necessary for cellular base-station applications. The operation and characteristics of the antenna are validated by the measurements. The measured results confirm the proposed antenna achieving fractional bandwidths of 13.31% (801.9–916.2 MHz) and 19.76% (1710.7–2085.7 MHz) for S11 ≤ −10 dB. It has stable unidirectional radiation patterns and optimum radiation gains of 9.2 dBi and 7.8 dBi at the first and second operating bands, respectively.