Antenna Efficiency Research Articles

Design and Fabrication of Broad-Beam Microstrip Antenna Using Parasitic Patches and Cavity-Backed Slot Coupling

The adjusting parasitic patch size technique for the broad-beam microstrip antenna array using the cavity-backed slot coupling is presented. The phase of each element of the microstrip array has been designed to emulate the reflection of waves on the surface of parabolic backscattering. In order to increase the efficiency of this array antenna, the back-slot cavity with an exciting probe will be employed for coupling the electromagnetic waves to the back of this array. The proper sizes and locations of patches and the optimized position of the cavity have been investigated by the Computer Science Technology (CST) Microwave Studio. The gain, the radiation pattern, the bandwidth, and the return loss are extensively analyzed. The fabricated antenna has the return loss of −22.39 dB, the bandwidth of 47 MHz (4.975–5.022 GHz), and the maximum directive gain of 5.6 dB at 5 GHz, and it can produce a wide beam width (half-power beam width around 130°). The antenna could be applied for wide applications in the wireless communications system. In particular, this realizing antenna covers the low earth orbit (LEO) satellite beam.

Förster Resonance Energy Transfer Rate and Efficiency in Plasmonic Nanopatch Antennas

AbstractSuccessful control of Förster resonance energy transfer (FRET) through the engineering of the local density of optical states (LDOS) will allow us to develop novel strategies to fully exploit this phenomenon in key enabling technologies. Here we present an experimental and theoretical study on the effect of the LDOS on the FRET rate and efficiency in plasmonic nanopatch antennas formed between a gold nanoparticle and an extended silver film. Our results reveal that plasmonic nanopatch antennas of similar levels of LDOS exhibit comparable levels of FRET rate and FRET efficiency, demonstrating that LDOS plays an important part in controlling both FRET rate and efficiency. Our findings contribute to the ongoing debate about the relation between the FRET process and the LDOS, as well as directly impacting the development of novel FRET based light harvesting and sensing devices.

Standalone stretchable RF systems based on asymmetric 3D microstrip antennas with on-body wireless communication and energy harvesting

As an indispensable component, the stretchable antenna with the potential use in wireless communication and radio frequency (RF) energy harvesting can provide future wearable electronics with a low profile and integrated functions. However, mechanical deformations applied to stretchable antennas often lead to a shift of their resonant frequency (i.e., the detuning effect), which limits their applications to strain sensing. In addition, the on-body radiation efficiency of stretchable antennas severely degrades due to lossy human tissues. In this work, we introduce stretchable microstrip antennas with varying 3D configurations for excellent on-body radiation performance. Compared to their 2D counterpart, the stretchable 3D microstrip antennas showcase a strain-insensitive resonance, improved stretchability, and enhanced peak gain. In particular, the optimized peak gain from the stretchable asymmetric 3D microstrip antenna allows it to wirelessly transmit the energy and data at an almost doubled distance, as well as a doubled charging rate from the harvested RF energy. More importantly, the integration of stretchable antenna and rectenna with stretchable sensing and energy storage units can yield a standalone stretchable RF system for future health monitoring of humans and structures. The results from this work can also pave the way for the development of self-powered units with wireless transmission capabilities for stretchable body area networks and smart internet-of-things.

Nano-antenna array for high efficiency sunlight harvesting.

Solar rectennas are promising devices for energy harvesting. Capability of rectennas to convert incident light into useful energy depends on the antenna efficiency, that is the ratio between the power transferred to the load vs the incoming power. In this work, we first emphasize that for the efficiency to be calculated accurately, antennas need to be treated as receiving devices, not as transmitting ones. Then, we propose an arrangement of antennas that differs from those published so far in three respects: (1) the proposed arrangement is formed by an array of nano-antennas with sub-wavelength inter-element spacing, (2) it comprises a reflecting mirror, and (3) it allows for dual polarization operation. Through numerical simulations, we show that the small lattice pitch we use is responsible for frequency flattening of the lattice impedance over the whole solar spectrum, eventually allowing for excellent matching with the antennas' loads. Also, the small pitch allows for a smooth dependence of the receiving efficiency on the angle of incidence of sunlight. Finally, we show numerically that the reflecting mirror also allows for an almost complete cancellation of light scattered by the receiving antennas. The final result is a polarization insensitive receiving theoretical efficiency larger than 70% over the whole 300-3000nm spectral range, with a less than 10% energy wasting due to back-scattering of sunlight.

Low-Profile Scanloss-Reduced Integrated Metal-Lens Antenna

Integrated lens antennas are widely used in high gain and beam steering applications at millimeter-wave frequencies. The ILA has often large height and suffers from significant scan loss. In this article, we demonstrate a low-profile, efficient, and scanloss-reduced integrated metal-lens antenna (IMLA). An IMLA is a combination of a dielectric lens and metal–plate lens. A 16- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> diameter IMLA is designed using the HDPE and 58 stainless steel plates to achieve the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f/d$ </tex-math></inline-formula> of 0.69. The simulated aperture and radiation efficiency of the IMLA are 73% and 92%, respectively. At 76 GHz, the simulated and measured realized gains of the fabricated IMLA are 31.24 and 31 dBi, respectively. The IMLA is designed to steer the main beam to ±30°. The scan loss is reduced by tilting the radiation pattern of the feeds at offset positions along the focal plane. The radiation pattern of the square waveguide feed is tilted using asymmetrical dielectric pins. The asymmetrical dielectric pins reduce the simulated gain scan loss of the IMLA by more than 1.5 dB at 30° steering angle. The simulation results show that the inclination of the feed radiation pattern helps limit the scan loss of the IMLA to 4.1 and 4.3 dB in the H- and E-planes for 30° steering angle, respectively. The measured scan loss of the manufactured IMLA is 3.8 and 6.2 dB in the H- and E-plane, respectively.

Highly Efficient Broadband Pyramidal Horn Antenna With Integrated H-Plane Power Division

The concept and development of a highly efficient pyramidal horn is described. The radiating element comprises a rectangular radiating aperture fed by two smaller flared square waveguide sections via a bifurcated H-plane surface discontinuity. For the simultaneous feeding of the two-port radiating element, the total antenna includes a compact H-plane power divider. Properly weighted TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{n0}$ </tex-math></inline-formula> modes ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n\in N^{\ast }$ </tex-math></inline-formula> ) are excited at the output of the two flared waveguide sections. The bifurcation is responsible for the recombination of the incoming fields. The low-dispersive modal coupling coefficients (or transmission coefficients of the bifurcation’s generalized scattering matrix) between the excitation and the aperture modes enable the broadband realization of the targeted aperture modal content. The common waveguide section is responsible for the phase alignment of the aperture modes. The design method targets a preoptimized model, which approximates the amplitude of the aperture modes TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{m0}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$m = 1, 3, 5, \ldots $ </tex-math></inline-formula> ) in the order of 1/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$m$ </tex-math></inline-formula> and minimizes their relative phase difference. Finally, maximum aperture efficiency can be achieved by fine tuning and with low computational complexity. Design principles are given and illustrated by means of an example involving an antenna with aperture size of about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.8\lambda _{0} \times 1.4\lambda _{0}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at the central frequency of operation). The antenna exhibits aperture efficiency levels above 95% over the entire Ku-Tx-band (10.7–12.75 GHz), as well as a compact profile ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.1\lambda _{0}$ </tex-math></inline-formula> ). The measured results of a prototype manufactured through milling verify experimentally the numerically predicted performance.

Toward an optimum design of fractal sausage Minkowski antenna for GPS applications

Fractal is one of the important tools to produce efficient and well-suited antennas for navigation systems. A novel design of broadband fractal sausage Minkowski antenna is described in this research article. Sausage Minkowski is designed and simulated for global positioning system (GPS) application that relies on fractal geometry using computer simulation studio microwave (CST MW) software. The substrate sheet is Roger TMM4 has of 4.5 dielectric constant and 1.6 mm altitude. A small metallic patch over a large metallic ground layer is made of perfect electric conductor (PEC) material. The suggested fractal antenna can be used efficiently in the military applications which demand a narrow spectrum and a tiny antenna profile. By introducing four various levels of fractal iteration models and compared each one to the other. The main aim of this work is to increase antenna gain and reduce the antenna size, in addition to improving the semi-flat voltage standing wave ratio (VSWR) with respect to decreasing the resonance frequency is. For 10% decrease in the frequency for the 3rd iteration value led to a clear improvement in the antenna characteristics such as directivity, gain, and VSWR. The reflection coefficient and bandwidth remain in range.

Wearable Circular Polarized Antennas for Health Care, 5G, Energy Harvesting, and IoT Systems

Novel circular polarized sensors and antennas for biomedical systems, energy harvesting, Internet of Things (IoT), and 5G devices are presented in this article. The major challenge in development of healthcare, IoT, 5G and communication systems is the evaluation of circular polarized active and passive wearable antennas. Moreover, a low-cost wearable sensor may be evaluated by printing the microstrip antenna with the sensor feed network and the active devices on the same substrate. Design considerations, comparison between simulation and measured results of compact circular polarized efficient sensors for wireless, 5G, energy harvesting, IoT, and medical systems are highlighted in this article. The electrical performance of the novel sensors and antennas on and near the user body were evaluated by employing electromagnetic software. Efficient passive and active metamaterial circular polarized antennas and sensors were developed to improve the system electrical performance. The wearable compact circular polarized passive and active sensors are efficient, flexible, and low-cost. The frequency range of the resonators, without Circular Split-Ring Resonators CSRRs, is higher by 4% to 10% than the resonators with CSRRs. The gain of the circular polarized antennas without CSRRs is lower by 2 dB to 3 dB than the resonators with CSRRs. The gain of the new passive antennas with CSRRs is around 7 dBi to 8.4 dBi. The bandwidth of the new circular polarized antennas with CSRRs is around 10% to 20%. The sensors VSWR is better than 3:1. The passive and active efficient metamaterials antennas improve the system performance.

Computational Analysis of a 200 GHz Phased Array Using Lens-Coupled Annular-Slot Antennas

We report the design, simulation, and analysis of a THz phased array, using lens-coupled annular-slot antennas (ASAs) for potential beyond 5G or 6G wireless communications. For a prototype demonstration, the ASA employed was designed on a high resistivity Si substrate with a radius of 106 μm, and a gap width of 6 um for operation at 200 GHz. In order to achieve higher antenna gain and efficiency, an extended hemispherical silicon lens was also used. To investigate the effect of the silicon lens on the ASA phased array, a 1 × 3 array and 1 × 5 array (the element distance is 0.55λ) were implemented with a silicon lens using different extension lengths. The simulation shows that for a 1 × 3 array, a ±17° scanning angle with an about −10 dB sidelobe level and 11.82 dB gain improvement (compared to the array without lens) can be achieved using a lens radius of 5000 μm and an extension length of 1000 μm. A larger scanning angle of ±31° can also be realized by a 1 × 5 array (using a shorter extension length of 250 μm). The approach of designing a 200 GHz lens-coupled phased array reported here is informative and valuable for the future development of wireless communication technologies.

Fabrication of Efficient Single-Emitter Plasmonic Patch Antennas by Deterministic In Situ Optical Lithography using Spatially Modulated Light.

Single-emitter plasmonic patch antennas are room-temperature deterministic single-photon sources, which exhibit highly accelerated and directed single-photon emission. However, for efficient operation these structures require 3D nanoscale deterministic control of emitter positioning within the device, which is a demanding task, especially when emitter damage during fabrication is a major concern. To overcome this limitation, the deterministic room-temperature in situ optical lithography protocol uses spatially modulated light to position a plasmonic structure nondestructively on any selected single-emitter with 3D nanoscale control. Herein, the emission statistics of such plasmonic antennas that embed a deterministically positioned single colloidal CdSe/CdS quantum dot, which highlight acceleration and brightness of emission, are analyzed. It is demonstrated that the presented antenna induces a 1000-fold effective increase in the absorption cross-section, and, under high pumping, these antennas show nonlinearly enhanced emission.

Polarization-Insensitive Unit Cells for a Cost-Effective Design of a 3-D-Printed Fresnel-Lens Antenna

A 3-D printed Fresnel-lens antenna formed by dielectric unit cells insensitive to polarization is presented in this article. The proposed unit cell can be implemented in any azimuth orientation, simplifying the design and the implementation of the Fresnel subzones, which is an advantage over the previous 3-D-printed Fresnel-lens designs. The unit cell exhibits a T-shaped geometry capable of providing no change in relative permittivity under TE polarizations orthogonal to each other. The novel design of the unit cell also provides robustness under oblique incidence and frequency. These features allow the radial arrangement of the unit cells to configure the subzones of the Fresnel lens, ensuring the desired relative permittivity. Additionally, the geometry of the printed unit cells enables self-supported subzones with the minimum number of unit cells per subzone. A 3-D-printed prototype of the proposed Fresnel lens was manufactured by stereolithography (SLA). The measurement results showed a good agreement with the simulated ones. The measured gain was 26.5 ± 0.5 dBi from 55 GHz to 65 GHz with a mean antenna efficiency of 79%.

An energy efficient resource allocation and transmit antenna selection scheme in mm‐wave using massive multiple‐input multiple‐output technology

SummaryThe massive multiple‐input multiple‐output (MIMO) improves the reliability of transmission and capacity of the channel. Resource allocation (RA) and transmit antenna selection (TAS) can minimize the complexity in implementation and hardware costs. In this research, both the RA and the TAS of wireless communication in millimeter‐wave (mm‐wave) with massive MIMO technology are considered. Two different solutions are developed for this research such as the deep learning method for efficient resource allocation process and optimization algorithm for TAS process. Here, the RA process is done with the help of attention‐based capsule auto‐encoder (ACAE) architecture which allocates the radio resources like power, space, time and frequency to all the available users in the system. Further, battle royale optimization (BRO) algorithm is utilized to select an efficient antenna from multiple antennas at BS. This optimization algorithm optimally selects an efficient antenna so that, user equipment (UEs) can create high quality links and achieves a reduced power consumption rate of the whole architecture. The overall system performance depends on the selection of optimal antenna which in terms enhances spectral efficiency (SE), energy efficiency (EE), reliability, and diversity gain of MIMO technology. In this way, both RA and optimal antenna selection schemes are performed to maximize the overall performance of wireless communication with massive MIMO technology for 5G wireless communication applications. The implementation of the proposed methodology is evaluated on MATLAB. Finally, the efficiency of the developed method is improved with respect to the capacity, EE, and SE.

Performance Improvement of Aperture Coupled MSA through Si Micromachining

In recent times rectangular patch antenna design has become the most innovative and popular subject due to its advantages, such as being lightweight, conformal, ease to fabricate, low cost and small size. In this paper design of aperture coupled microstrip patch antenna (MSA) on high index semiconductor material coupled with micromachining technique for performance enhancement is discussed. The performance in terms of return loss bandwidth, gain, cross-polarization and antenna efficiency is compared with standard aperture coupled antenna. Micromachining underneath of the patch helps in to reduce the effective dielectric constant, which is desirable for the radiation characteristics of the patch antenna. Improvement 36 percent and 18 percent in return loss bandwidth and gain respectively achieved using micromachined aperture coupled feed patch, which is due to the reduction in losses, suppression of surface waves and substrate modes. In this article along with design, fabrication aspects on Si substrate using MEMS process also discussed. Presented antenna design is proposed antenna can be useful in smart antenna arrays suitable in satellite, radar communication applications. Two topologies at X-band are fabricated and comparison between aperture coupled and micromachined aperture coupled are presented. Index Terms—Microstrip Patch Antenna, Aperture Coupled, Micromachining, High Resistivity Silicon

Average Rician K-Factor-Based Uncertainty Model of Measured Antenna Efficiency Using the Reference Antenna Method in Reverberation Chambers

Along several decades of development, many methods based on reverberation chambers (RCs) have been proposed for accurate and efficient measurement of antenna efficiency. The standard reference antenna method (RAM) is applicable for almost all frequency bands of interest and all types of antennas, and thus, it may well be the most widely applied method in the industry. In this article, an average Rician <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> -factor-based uncertainty model for the standard RAM is proposed. It takes both the number of independent samples and the nonideality of the RC into consideration. Extensive measurements are performed for different RC configurations. It is shown that the newly proposed uncertainty model provides good and stable estimations of the measurement uncertainties for both unloaded and loaded RCs. Moreover, it is experimentally verified that the differences in the radiation characteristics between the reference antenna and the antenna under test (AUT) have little effect on measurement uncertainty regardless of the loading conditions of the RC. The findings of this work allow more flexible and efficient antenna efficiency measurements, including estimation of the associated uncertainty.

A Wideband and High-Gain All-Metallic Perpendicular-Corporate-Fed Multi-Layered Parallel-Plate Slot Array Antenna

An all-metallic multi-layered parallel-plate slot array antenna operated in the 60-GHz band with wide impedance bandwidth and high-gain characteristics is proposed. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16\,{\times }\,16$ </tex-math></inline-formula> -slot antenna is composed of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\,{\times }\,2$ </tex-math></inline-formula> -slot subarrays perpendicularly-fed by a hollow waveguide corporate feeding network. The subarray is partitioned into three functional layers including a bottom one for feeding, a mediate one for radiating and a parasitic one atop for bandwidth enhancement. An undesired resonance of a high-order mode introduced with the parasitic layer is eliminated by loading metal grids between the slotted plates. The contribution of the parasitic layer on bandwidth improvement is verified by a measured 19.2% bandwidth of the antenna with reflection below −10 dB. The removal of the dielectric plate loaded in the conventional double-layered counterpart also contributes to the better performance of the array. The all-metallic feature exempts the design from dielectric loss and beneficial for realizing a higher gain. A high aperture efficiency over 90% is realized over a 19.3% bandwidth and an antenna efficiency over 70% is obtained over a 18.5% bandwidth for the fabricated prototype antennas. The measured realized gain is up to 33.2 dB and the antenna efficiency is 87.2% at 62.0 GHz.

Novel Design of UWB Jeans Based Textile Antenna for Body-Centric Communications

This research presents an ultra-wideband (UWB) textile antenna design for body-centric applications. The antenna is printed on a 1 mm thick denim substrate with a 1.7 relative permittivity. The jeans substrate is sandwiched between a partial ground plane and a radiating patch with a Q-shaped slot. The slotted radiating patch is placed above the substrate and measures 27.8 mm × 23.8 mm. In free space, the antenna covers the ultra-wideband spectrum designated by the Federal Communication Commission (FCC). Various parameters of the antenna design were changed for further performance evaluation. Depending on the operating frequency, the antenna's realized gain varied from 2.7 to 5 dB. The antenna achieved high radiation efficiency with an omnidirectional radiation pattern. A parametric study was performed in research on varying antenna substrates and other components of the antenna. The three outermost layers of the human body are used to model a human phantom for on-body simulation. After that, the antenna was placed at five different distances from the phantom. The findings demonstrate that at close distances to the phantom, the antenna's gain and efficiency at lower frequencies are reduced. The antenna's radiation efficiency and gain were much higher at higher frequencies for distances greater than 6 mm. Compared to free space, the antenna's radiation pattern was more omnidirectional, especially at higher frequencies. This antenna is novel, compact and has an ultra wide bandwidth, a maximum of 94.60% radiation efficiency and a 5 dBi gain that will make it a good candidate for body-centric communications.

Quad-Furcated Profiled Horn: The Next Generation Highly Efficient GEO Antenna in Additive Manufacturing

A novel compact and highly efficient dual-polarized horn-like antenna is presented. It exploits a radiating aperture that is fed by four smaller waveguides via a quad-furcated junction. The antenna also comprises the full feed network for the feed waveguides including an integrated 4-way orthomode power divider. Design principles are described in detail and illustrated by means of an example involving an antenna with aperture size of 2.6λ0×2.6λ0 (λ0 the wavelength at the central frequency of operation) intended primarily for Geostationary Orbit (GEO) satellites. The antenna feed was designed to comply with the Additive Manufacturing rules and exhibits aperture efficiency levels close to the theoretical maximum ones over the entire transmit Ku band (10.7 -12.75 GHz), while at the same time its profile is highly compact (6.4λ0). The measured results of a prototype 3D-printed in Selective Laser Melting (SLM) verified experimentally the calculated high aperture efficiency (over 90%). The total antenna feed attains return loss > 19 dB and maximum cross-polarization isolation (XPI) > 24 dB over a bandwidth of 18%. In light of the favorable electrical performances and compact size, the proposed solution constitutes an appealing alternative to profiled (or spline) horns for satellite antenna systems used either as reflector feeds or direct radiating arrays.

Расчет двузеркальной антенны по методу физической оптики с учетом многократных переотражений.

Calculation of a double reflector Cassegrain antenna by physical optics method with taking into account multiple reflections between the reflector and the subreflector was performed. It was shown that the convergence of antenna characteristics (gain, antenna efficiency, side-lobe level) with the increase of accounting reflections is observed. To check the method of multiple reflections the same Cassegrain antenna was calculated by the method of electric field integral equation with the unknown surface electric currents on the reflector and the sub-reflector. The comparison showed the coincidence of the result obtained by two different methods. The calculation of gain and efficiency of a Cassegrain antenna in frequency range from 1 to 10 GHz was performed by physical optics method with multiple reflections.

A Compact Self-Isolated MIMO Antenna System for 5G Mobile Terminals

A compact self-isolated Multi Input Multi Output (MIMO) antenna array is presented for 5G mobile phone devices. The proposed antenna system is operating at the 3.5 GHz band (3400–3600 MHz) and consists of eight antenna elements placed along two side edges of a mobile device, which meets the current trend requirements of full-screen smartphone devices. Each antenna element is divided into two parts, a front part and back part. The front part consists of an I-shaped feeding line and a modified Hilbert fractal monopole antenna, whereas the back part is an L-shaped element shorted to the system ground by a 0.5 mm short stub. A desirable compactness can be obtained by utilizing the Hilbert space-filling property where the antenna element’s overall planar size printed on the side-edge frame is just (9.57 mm × 5.99 mm). The proposed MIMO antenna system has been simulated, analyzed, fabricated and tested. Based on the self-isolated property, good isolation (better than 15 dB) is attained without employing additional decoupling elements and/or isolation techniques, which increases system complexity and reduces the antenna efficiency. The scattering parameters, antenna efficiencies, antenna gains, and antenna radiation characteristics are investigated to assess the proposed antenna performance. For evaluating the proposed antenna array system performance, the Envelope Correlation Coefficients (ECCs), Mean Effective Gains (MEGs) and channel capacity are calculated. Desirable antenna and MIMO performances are evaluated to confirm the suitability of the proposed MIMO antenna system for 5G mobile terminals.

Wideband Four-Port Single-Patch Antenna Based on the Quasi-TM1/2,1/2 Mode for 5G MIMO Access-Point Application

A wideband four-port single-patch antenna for fifth-generation (5G) MIMO access-point application in 3.3-5.0 GHz (41% centered at 4.15 GHz) is presented. The antenna uses a simple square patch of size 42 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$ </tex-math></inline-formula> 42 mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.58 \boldsymbol {\lambda } \times 0.58 \boldsymbol {\lambda } $ </tex-math></inline-formula> at 4.15 GHz) mounted 10 mm above a ground plane. To generate four isolated waves in a wide band for MIMO application, the square patch is short-circuited to the ground plane using four simple L-shape metal walls to form four resonant quadrants for the quasi-TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2,1/2</sub> mode excitation. Each resonant quadrant is excited using a slot-coupled probe feed to have dual-resonance behavior with good impedance matching over a wide band. It is obtained that the single-patch antenna can generate four isolated waves in 3.3-5.0 GHz with impedance matching better than −10 dB, port isolation >15 dB, antenna efficiency >80%, and envelope correlation coefficients <0.03. Details of the proposed antenna are presented. An extended design for enhanced port isolation of the proposed antenna is also studied.