Antenna Configuration Research Articles

Multi-band frequency reconfigurable antenna using EBG and parasitic patches

ABSTRACT This article demonstrated a compact reconfigurable microstrip antenna with a multi-band configuration. It resonates for three different frequency configurations, including the single and dual bands. The primary rectangular patch antenna resonates for WLAN (5.2 GHz center frequency) band. The reconfigurable electromagnetic bandgap (EBG) and parasitic patches near the feed line produce 4 and 6.33 GHz resonance. The defected ground structure is integrated with a PIN diode to make reconfigurable EBG, and it resonated at C band (4 GHz). The PIN diode switching configuration embedded with EBG and one square patch creates dual-band characteristics in wireless local-area network (WLAN) and International Telecommunication Union (ITU) bands. Other PIN diodes switching configurations with primary antenna and two other patches work for C and WLAN bands. The proposed antenna resonated at 4, 5.2, and 6.33 GHz frequencies with different switching configurations of the PIN diode. The simulated results of this novel antenna configuration verified with measured consequences for antenna parameters like reflection coefficient and radiation characteristics are also presented.

Improving the VSSNLMS adaptive beamformer for adaptive antenna systems

A new configuration for the adaptive beamforming technology has been presented in this research work. We modified the structure of the uniform linear array (ULA) in such a way that a correct beam can be formed uniformly for all azimuth angles. For ULA composed of M antennas, we place two extra elements on the top and the bottom of the configuration of the ULA (at the array axis). Then, we develop the mathematical model or the same. To investigate the efficacy of the proposed antenna configuration, we deploy the VSSLMS beamformer. The new beamformer is compared with the well-known LMS and the MLMS adaptive beamformer. Computer simulations are provided in the result section of this paper to validate that the new beamformer has enhanced convergence rate and high data transmission compared to the LMS and the NLMS methods. Also, the new method has the same performance for middle angles, near boresight and array end fires which is not possible for the LMS and the NLMS method using a ULA.

A wideband monopole antenna with diplexer and rectifier for simultaneous energy harvesting and data communication

A wideband coplanar waveguide fed monopole antenna with diplexer and rectifier for microwave wireless power transmission and communication is proposed. The antenna is comprised of an asymmetric ground plane with an open stub, a rectangular monopole, and a square loop with a gap at the bottom. A microstrip line diplexer is implemented by using stepped impedance resonator slots to split the signal without extra matching circuits. A microwave rectifier based on the voltage doubler topology is designed for wireless power transmission. The prototypes are fabricated, measured, and compared with the simulated results. Measured results demonstrate that the −10 dB impedance bandwidth (1.42 GHz) of the antenna reaches 69.6% (1.33–2.75 GHz), the diplexer minimum insertion losses ( S 21 $$ \left|{S}_{21}\right| $$ , S 31 $$ \left|{S}_{31}\right| $$ ) are 2.13 dB, 3.27 dB at pass band frequencies, the output isolation ( S 23 $$ \left|{S}_{23}\right| $$ ) better than 20 dB from 1 to 3 GHz, and the peak RF to DC conversion efficiency of a rectifier is 56%. The integration of the proposed antenna, diplexer, and rectifier novel configuration is suitable for simultaneous wireless power transmission and communication applications.

Miniaturization and performance enhancement of super wide band four element MIMO antenna using DNG metamaterial for THz applications

A compact semi-hexagonal-shaped MIMO antenna loaded with a planar SRR (split-ring resonator) structure is presented for Terahertz applications. The single radiating element consists of a semi-hexagonal shape metallic patch loaded with SRR-CC (Split ring Resonator-Connected C shape) metamaterial unit cell to enhance the impedance bandwidth as well as gain of the proposed antenna. The proposed antenna element can be easily extended into two-port and four-port MIMO antenna configurations. Four radiating elements of the proposed antenna are printed on 122.4*122.4 μm2 quartz substrate having a thickness of 10 μm. The radiating elements are placed orthogonally to achieve high isolation and miniaturization in the MIMO system. The proposed antenna exhibits super-wide impedance bandwidth (S11 ≤ − 10 dB) in the range of 0.9–10.1 THz (with fractional bandwidth of 168% at f0 = 5.5 THz) while isolation of antenna is more than 20 dB in the whole operating band. The peak gain of the antenna is 7.51 dBi with more than 95% radiation efficiency in the entire band. The stable radiation pattern, high gain, high radiation efficiency, and good diversity performance of the proposed antenna make it suitable for many THz applications such as breast cancer detection, sugar measurement, drug detection.

Downlink Precoding for DP-UPA FDD Massive MIMO via Multi-Dimensional Active Channel Sparsification

In this paper, we consider user selection and downlink precoding for an over-loaded single-cell massive multiple-input multiple-output (MIMO) system in frequency division duplexing (FDD) mode, where the base station is equipped with a dual-polarized uniform planar array (DP-UPA) and serves a large number of single-antenna users. Due to the absence of uplink-downlink channel reciprocity and the high-dimensionality of channel matrices, it is extremely challenging to design downlink precoders using closed-loop channel probing and feedback with limited spectrum resource. To address these issues, a novel methodology – active channel sparsification (ACS) – has been proposed recently in the literature for uniform linear array (ULA) to design sparsifying precoders, which substantially reduces channel feedback overhead. Pushing forward this line of research, we aim to facilitate the potential deployment of ACS in practical FDD massive MIMO systems, by extending it from ULA to DP-UPA with explicit user selection and making the current ACS implementation simplified. To this end, by leveraging Toeplitz matrix theory, we start with the spectral properties of channel covariance matrices from the lens of their matrix-valued spectral density function. Inspired by these properties, we extend the original ACS using scalar-weight bipartite graph representation to the matrix-weight counterpart. Building upon such matrix-weight bipartite graph representation, we propose a multi-dimensional ACS (MD-ACS) method, which is a generalization of original ACS formulation and is more suitable for DP-UPA antenna configurations. The nonlinear integer program formulation of MD-ACS can be classified as a generalized multi-assignment problem (GMAP), for which we propose a simple yet efficient greedy algorithm to solve it. Simulation results demonstrate the performance improvement of the proposed MD-ACS with greedy algorithm over the state-of-the-art methods based on the QuaDRiGa channel models.

Spectrum Shaping for Multiple Link Discovery in 6G THz Systems

This paper presents a novel antenna configuration to measure directions of multiple signal sources at the receiver in a THz mobile network via a single channel measurement. Directional communication is an intrinsic attribute of THz wireless networks and the knowledge of direction should be harvested continuously to maintain link quality. Direction discovery can potentially impose an immense burden on the network that limits its communication capacity exceedingly. To utterly mitigate direction discovery overhead, we propose a novel technique called spectrum shaping capable of measuring direction, power, and relative distance of propagation paths via a single measurement. We demonstrate that the proposed technique is also able to measure the transmitter antenna orientation. We evaluate the performance of the proposed design in several scenarios and show that the introduced technique performs similar to a large array of antennas while attaining a much simpler hardware architecture. Results show that the spectrum shaping with only two antennas placed 0.5 mm, 5 mm, and 1 cm apart performs direction of arrival estimation similar to a much more complex uniform linear array equipped with 7, 60, and 120 antennas, respectively.

A Deionized Water-Infilled Dual-Layer Insulator-Applied Brain-Implanted UWB Antenna for Wireless Biotelemetry Applications

We propose a novel double-layered insulator configuration for a human-brain-implanted impulse radio ultra-wideband (IR-UWB) antenna. The dimension of the antenna is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10.0\times 11.0\times0.954$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , including the dual-layer insulator. The insulator provides a dielectric loading effect of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon _{r}~\approx ~50$ </tex-math></inline-formula> (lossless) for obtaining an improved radiating power and the broadband-impedance-matching characteristic in brain tissues. The outer layer is made of biocompatible 3-D printing material, and the inner insulator is filled with deionized water with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon _{r}~\approx ~80$ </tex-math></inline-formula> and loss tangent (tan <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\delta$ </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">$\approx ~0.25$ </tex-math></inline-formula> at 4 GHz. A slotted UWB antenna with the proposed insulator is located between the emulated dura and CSF tissues inside the skull for brain signal detection. The design uses a multilayer phantom, mimicking the seven tissue layers of the brain. The impedance and radiation performance of the proposed antenna configuration are also discussed using the commercial high-precision human phantom model. The designed IR-UWB antenna shows a boresight radiation characteristic toward the top of the head with a proper high gain in the target frequency of 3–5 GHz. The computed expectations are verified experimentally. Furthermore, it is demonstrated that the UWB spectrum generated from a UWB radio-frequency (RF) transmitter can be transmitted stably using the proposed antenna as a transmitting antenna. In addition, the link budget of the system setup is analyzed. The improved gain characteristic of the antenna from the proposed dual-layer insulator can be utilized to retain the link margins while satisfying the UWB communication regulation and average specific absorption rate (SAR) limitation.

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.

Compact circularly polarized cross dipole antenna for RFID handheld readers/IoT applications

The radio frequency identification (RFID) and global positioning system (GPS) are employed for indoor and outdoor tracking scenarios. This paper presents an amalgamated identification mechanism for sensing and tracking in an Internet of things (IoT) network. A low-profile, compact, multi-functional antenna configuration is proposed for the amalgamation application. The antenna operates in the 915 MHz (UHF), 2.45 GHz, and 5.8 GHz RFID bands, along with the 1.575 GHz GPS L1 band. The presented antenna is a cross dipole configuration consisting of three pairs of dipole elements printed on both sides of the dielectric substrate. The first and third dipole pairs are larger and smaller metal strips with half-arrow shaped ends that excite the 915 MHz and 5.8 GHz bands, respectively. The second dipole pair is an asymmetric triangular-shaped radiator that excites the 1.575 GHz and 2.45 GHz bands. Using quarter wavelength ring delay lines, circular polarization is obtained in each band. The GPS band, in combination with the RFID bands, improves the efficiency and accuracy of the reader tracking device. The proposed multiband antenna prototype is fabricated on the 45° rotated substrate material, resulting in a compact size of 0.21λ0 × 0.21λ0 × 0.004λ0. The antenna simulation and measurement results are in close agreement.

Reconfigurable circular patch MIMO antenna for 5G (sub‐6 GHz) and WLAN applications

SummaryIn this article, a circular patch microstrip feed line monopole radiator with a dimension of 15 × 20 × 1.6 mm3 is proposed. An inverted L‐shaped stub is employed in the partial ground plane to achieve optimum bandwidth, radiation pattern and radiation efficiency. To further cover the sub‐6 GHz spectrum (3.4–3.8 GHz) for future 5G communications, a two‐element MIMO antenna configuration is designed by utilising the single element antenna. The edge‐to‐edge distance between the two elements is 0.15λ0 (15 mm). The propose antenna achieved dual‐operating bands of 3.35–4.60 and 4.93–5.19 GHz in the diode (D) = ON state. The minimum isolation between 3.35–3.94 and 4.99–5.16 GHz frequency range is −14.5 and −12.5 dB, respectively, by incorporating a rectangular stub between two inverted L‐shaped stubs. The MIMO antenna has a peak gain of 2.68 dBi at 5.1 GHz frequency. The average total efficiency at port‐1 between 3.35–3.94 and 4.93–5.19 GHz frequency range is 65%, whereas at port‐2 is 75%. In terms of the envelop correlation coefficient (ECC), mean effective gain (MEG) and total active reflection coefficient (TARC), the proposed antenna's diversity performance characteristics are investigated and the obtained values are 0.09, ±3 and −3 dB, respectively. The suggested MIMO antenna is designed on a FR4 substrate with a dielectric constant of 4.4 and an electrical dimension of 0.34λ0 × 0.20λ0 × 0.015λ0 mm3 (where λ0 represents the free space wavelength at lower cut‐off frequency [2.95 GHz]). Therefore, the proposed antenna can find applications for rain or fog as well as for identification and tracking (weather radar) on S‐band at 3 GHz frequency, 5G (sub‐6 GHz) and WLAN applications.

A Novel Design and Development of a Strip-Fed Circularly Polarized Rectangular Dielectric Resonator Antenna for 5G NR Sub-6 GHz Band Applications.

In this article, a rectangular dielectric resonator antenna (RDRA) with circularly polarized (CP) response is presented for 5G NR (New Radio) Sub-6 GHz band applications. A uniquely shaped conformal metal feeding strip is proposed to excite the RDRA in higher-order mode for high gain utilization. By using the proposed feeding mechanism, the degenerate mode pair of the first higher-order, i.e., at 4.13 GHz and at 4.52 GHz is excited to achieve a circularly polarized response. A circular polarization over a bandwidth of ~10%, in conjunction with a wide impedance matching over a bandwidth of ~17%, were attained by the antenna. The CP antenna proposed offers a useful gain of ~6.2 dBic. The achieved CP bandwidth of the RDRA is good enough to cover the targeted 5G NR bands around 4.4–4.8 GHz, such as n79. The proposed antenna configuration is modelled and optimized using computer simulation technology (CST). A prototype was built to confirm (validate) the performance estimated through simulation. A good agreement was observed between simulated and measured results.

Geolocation-based sector selection for Vehicle-to-Infrastructure 802.11ad communication

To improve range, IEEE 802.11ad uses directional communication, the first step of which is to choose the best antenna configuration, known as sector. We studied the sector selection behavior of Commercial Off-The-Shelf (COTS) 802.11ad equipment in an experimental Vehicle-to-Infrastructure (V2I) communication scenario. First, we created a framework for mm-Wave data collection in mobile scenarios, highlighting the challenges, justifying our solutions, and making them available, thus flattening the path for future experimentation by others. We then proceeded to use said framework to collect data in a realistic V2I communication scenario. We performed two independent measurement campaigns in the same area. Analysis of the collected data revealed the following inefficiencies in the devices’ sector selection algorithm: (i) a large number of sector selection attempts that do not result in a sector change; and (ii) a “ping-pong” effect in which a node oscillates between two sectors. With this in mind we propose an alternative antenna sector selection scheme that uses spatially-indexed historical performance data to pick the statistically-best sector for any given geolocation. A trace-based analysis showed that a position-based strategy can improve throughput by more than 10% for 30% of locations, and that gains can be as high as 60%, in some instances.

A compact quad element MIMO antenna for LTE/5G (sub-6 GHz) applications

Abstract In this paper, a compact I shaped monopole radiator with a dimension of 24 × 22 × 1.6 mm3 is proposed. The monopole radiator achieved an impedance bandwidth of 1.46 GHz (4.06–5.52 GHz) using partial ground plane. Further to cover the sub-6 GHz spectrum (3.4–3.6 GHz) for future 5G communications, a four-element multi-input multi-output (MIMO) antenna configuration is designed by utilizing the single element antenna. The operation bandwidth of 2.27 GHz (3.37–5.64 GHz) is enhanced by using a tapered microstrip feed line. Isolation is increased upto 40 dB over the operating band (3.37–5.64 GHz) by using a modified rectangular stub in the partial ground plane. This stub also provides a decoupling path and consequently limited amount of current couples to the neighbouring element due to surface waves. The modified stub suppress the surface waves and the near fields reducing the coupling between the antennas keeping it below −10 dB for the whole desired frequency range. Therefore, the proposed MIMO antenna achieved wide bandwidth of (3.37–5.64 GHz) and minimum isolation between antenna elements 1 &amp; 4 is −10 dB in 3.4–3.6 GHz frequency band, whereas −15 dB between 3.8 and 5.64 GHz frequency band. The suggested MIMO antenna is designed on a FR4 substrate with a dielectric constant of 4.4 and a loss tangent of 0.02 and a 0.45λ 0 × 0.45λ 0 dimension. In terms of the envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), total active reflection coefficient (TARC), isolation between the ports, and channel capacity loss (CCL), the proposed antenna’s diversity performance characteristics are investigated and the obtained values are 0.04, 9.98, ±3, −11, −15 dB, 0.10 bits/s/Hz respectively. The antenna prototypes have been fabricated, and the measurements and simulations have been found to be in close agreement. Therefore, the proposed MIMO antenna covers n77/n78/n79 for 5G (sub-6 GHz) and LTE bands of 42/43/46.

Energized IOT Sensor through RF Harvesting Energy

Wireless Power Collecting (WPC) present the future in powering and energizing intelligent Internet of Things (IoT) electronics devices. This chapter studies and utilizes a circuit to powering wirelessly IoT devices. The WPC offer a best technique to help researchers and engineers of modern societies to build cell blocks. The concept is to energy any IoT devices and sensors wirelessly from Radio Frequency (RF) power strength in the same areas that may be hard to achieve or potentially hazardous. We implemented the RF harvesting technology with IoT devices to increase the efficiency of sensors. The idea of this system is to power up and self-energize any IoT sensors wirelessly. This work studies two different topologies of a rectangular patch antenna and different RF harvesting circuit voltage multiplier configurations using a microwave power station as the input RF source. This work aims to utilize the wireless power transmission technique in the smart house solution. The proposed prototype gets all technical parameters to generate enough electricity to power up the bulbs 5 W wirelessly at a gap distance around a five meters. Finally, we test the RF rectifier circuit coupled with a twin patch antenna that can self-energize the bulb, eventually devices work without batteries.

MTM-Inspired Graphene-Based THz MIMO Antenna Configurations Using Characteristic Mode Analysis for 6G/IoT Applications

6G wireless communications will be immersed in the future with different applications. It is expected to support all IoT services and satellite communications, and it is expected to support artificial intelligence (AI) and machine learning (ML). The THz frequency band has a vital role in 6G communication. In this study, a new graphene plasmonic two-port Terahertz (THz) MIMO antenna is analyzed by the characteristic mode theory (CMA), which gives a better insight into the physical behavior of the MIMO configurations. The proposed MIMO antenna is compact and designed on a Teflon substrate of 130 × 85 µm2. The antenna provides a wide impedance bandwidth of 0.6 THz (3.2–3.8 THz). The CMA is applied to clarify the position at which the mutual coupling gives a maximum concentrated current distribution. It is mainly used to reveal the preferable MIMO antenna configuration by the usage of the model significant and model current distribution property. To reduce the mutual coupling between the radiating elements, a complementary dumbbell-structure Metamaterial (MTM) unit cell is etched in the ground plane to block the coupling mode without any affection on the dominant mode. The preferred MIMO configuration gives high isolation of −55 dB between the radiating patches. The fundamental characteristics have been discussed in detail. The proposed MIMO design offers several attractive features such as large bandwidth of 0.6 THz, low envelope correlation coefficient (ECC) of 0.000168, compact size, stable radiation, high gain of 7.23 dB, and low channel capacity loss (CCL) of 0.006. The proposed MIMO design is suitable for different applications in the THz band according to the high-performance parameters such as biomedical applications, security scanning, sensing, IoT, and 6G high-speed wireless communication systems.

Impact of Antenna Pattern on TOA Based 3D UAV Localization Using a Terrestrial Sensor Network

In this article, we explore the fundamental limits of the 3-dimensional (3D) localization of unmanned aerial vehicles (UAVs) in conjunction with the effects of 3D antenna radiation patterns. Although localization of UAVs has been studied to some extent in the literature, effects of antenna characteristics on 3D localization remains mostly unexplored. To study such effects, we consider a scenario where a fixed number of radio-frequency (RF) sensors equipped with single or multiple dipole antennas are placed at some known locations on the ground, and they derive the time-difference-of-arrival (TDOA) measurements from the time-of-arrival (TOA) data collected for the UAV that is also equipped with a dipole antenna. We then use these measurements to estimate the 3D location of the UAV, and to derive the Cramer-Rao lower bounds (CRLBs) on the localization error for various orientations of the dipole antennas at the transmitter and the receiver. Namely, we consider vertical-vertical (VV), horizontal-horizontal (HH), and vertical-horizontal (VH) radiation patterns in a purely line-of-sight (LoS) environment and a mixed LoS/Non-line-of-sight (NLoS) environment. We show that the localization accuracy changes in a non-monotonic pattern with respect to the UAV altitude and identify the respective critical altitudes for each of the VV, VH and HH orientations. Subsequently, we propose a multi-antenna signal acquisition technique that mitigates the accuracy degradation due to the antenna pattern mismatches, and we derive the localization CRLB for the multi-antenna scenario. Our numerical results characterize achievable localization accuracy for various antenna configurations, UAV heights, and propagation conditions for representative UAV scenarios.

Electronic Beam-Scanning Antenna Based on a Reconfigurable Phase-Modulated Metasurface.

Metasurfaces (MSs) have enabled the emergence of new ideas and solutions in the design of antennas and for the control of electromagnetic waves. In this work, we propose to design a directional high-gain reconfigurable planar antenna based on a phase-modulated metasurface. Reconfigurability is achieved by integrating varactor diodes into the elementary meta-atoms composing the metasurface. As a proof of concept, a metasurface prototype that operates around 5 GHz is designed and fabricated to be tested in an antenna configuration. The metasurface is flexibly controlled by different bias voltages applied to the varactor diodes, thus allowing the user to control its phase characteristics. By assigning judiciously calculated phase profiles to the metasurface illuminated by a feeding primary source, different scenarios of far-field patterns can be considered. Different phase profiles are tested, allowing us to, firstly, achieve a highly directive boresight radiation and, secondly, to steer the main radiated beam towards an off-normal direction. The whole design process is verified by numerical simulations and is validated experimentally by far-field antenna measurements. The proposed metasurface enables the design of directive flat antennas with beam-scanning characteristics without complex feeding systems and power-consuming phase shifters, and thus provides potential interests for next generation antenna hardware.

A New Multi-Band Multi-Array Antenna Configuration With Scattering Suppression for Radiation Pattern Distortion Mitigation of Base Station

This communication presents a new multiband multiarray (MBMA) scattering suppression antenna configuration for a dual-band and dual-polarized antenna array with reduced radiation distortion. The proposed antenna array configuration consists of a low-band (LB) antenna element working in the 690–960 MHz band and four high-band (HB) antenna elements working in the 1.7–2.7 GHz band. The LB antenna introduces U-shape structures to the radiation element to neutralize HB scattering currents. On the other hand, the HB antenna involves an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonant structure between its radiation arm and feeding balun to suppress LB scattering currents. An antenna array using the proposed LB and HB elements is designed to achieve MBMA functions. Experimental results show that the radiation distortions in both LB and HB bands are improved significantly. The VSWR of less than 1.5, the isolation of more than 25 dB, and the symmetrical radiation pattern are obtained in both bands.

On the Performance of Mobile Cellular-Connected Drones Under Practical Antenna Configurations

Providing seamless connectivity to unmanned aerial vehicle user equipment (UAV-UE) is very challenging due to the encountered line-of-sight interference and reduced gains of down-tilted base station (BS) antennas. For instance, as the altitude of UAV-UEs increases, their cell association and handover procedure become driven by the side-lobes of the BS antennas. In this paper, the performance of cellular-connected UAV-UEs is studied under 3D practical antenna configurations. Two scenarios are studied: scenarios with static, hovering UAV-UEs and scenarios with mobile UAV-UEs. For both scenarios, the UAV-UE coverage probability is characterized as a function of the system parameters. The effects of the number of antenna elements on the UAV-UE coverage probability and handover rate are then investigated. Moreover, a lower bound on the handover probability is derived as a function of the number of antenna elements and the UAV-UE mobility speed. Results reveal that the UAV-UE coverage probability under a practical antenna pattern is lower than that under a simple antenna model. Moreover, vertically-mobile UAV-UEs are susceptible to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">altitude handover</i> due to consecutive crossings of the nulls and peaks of the antenna side-lobes. The effect of altitude handover is also shown to be effectively mitigated by serving UAV-UEs cooperatively from multiple ground BSs.

DESIGN OF MIMO ANTENNA FOR WIRELESS COMMUNICATION APPLICATIONS

The development of a new compact Ultra Wideband (UWB) antenna. The main advantages of the proposed array configuration are that it requires no isolation/decoupling circuit between the elements of the MIMO array. The suggested antenna has an impedance bandwidth of (3.1_10.6) GHz. The antenna dimension (25×58×1.6) mm3. It is based on a simple patch antenna configuration with a simple hexagonal radiator and partial ground. The partial ground is used to improve the reflection coefficient and isolation. A 16.54mm x 9mm ground plane is used. Each element was fed through a 50Ω microstrip transmission line (MTL). The suggested antenna is polarized linearly. It performs admirably at 10.46 GHz, with a gain of 1.77dB, a reflection coefficient of 28.42dB, VSWR approx 1, an envelope correlation coefficient very close to 0 dB, a diversity gain of 10dB, and isolation of 50.44dB, respectively, and suggested antenna's diversity characteristics, such as ECC and diversity gain, are also modeled.