Improved Radiation Efficiency Research Articles

Efficient High Gain Elliptically Polarized Phased MIMO Antenna

A phased MIMO antenna with a coaxial feed is designed to operate in the electromagnetic spectrum with the frequency range of 8 GHz to 12 GHz, which resonates at 9 GHz, is used in military and satellite communication. The ability of phased MIMO antennas to change the form and orientation of the radiation pattern without constantly moving the antenna is unique. The proposed approach can also improve radiation efficiency by maximizing array unit size. To validate the proposed method, an elliptical polarization phased antenna has been constructed as a planar array. A 2 to 2 planar dual polarized MIMO antenna is intended to improve the efficiency. The obtained return loss for 2x2 planar MIMO is -19.34 dB. The proposed 2x2 MIMO antenna is projected on a teflon material with dielectric constant of 2.25 and the thickness of the substrate is 7mm. The efficiency for two port MIMO antenna is 97.7%.

Improved microstrip ring resonator for dielectric response tests and moisture evaluation of oil-impregnated pressboard.

Moisture ingress is one of the major causes of aging in oil-paper insulated transformers; the measurement of the moisture content of the insulating material is thus necessary during transformer disassembly for maintenance. One critical engineering consideration is the need for rapid and nondestructive moisture content measurement of the oil-paper insulation to minimize the power-outage time. Herein, a rapid characterization method for the moisture content of oil-paper insulation based on the dielectric response obtained using a microstrip petal-like ring resonator (MPRR) is proposed. The geometric parameters of the resonator and dielectric response model were established based on simulations and theoretical analysis. The geometry of the resonant ring was optimized by modifying the originally circular ring structure of the microstrip ring resonator (MRR) into a petal-like ring structure; this increases the number of resonant peaks from five to seven in the frequency range of 0.5-6.0GHz for the same electrode area. The effects of the coupling mode, coupling gap, and microstrip ring size on the resonance characteristics of the MPRR were simulated and analyzed. Compared with the MRR, the MPRR has the advantages of a reduced fundamental resonant frequency and a smaller resonant-ring area that improves radiation efficiency. The impact of moisture content on the dielectric response of the pressboard obtained using the MPRR was studied. A moisture-calculation equation based on the measured dielectric response for a selected type of pressboard was established by the Lasso regression. The results of verification experiments show that the error of the proposed method is sufficient for practical applications.

Miniaturized Time-Domain Antenna With Improved Low-Frequency Radiation Performance

A miniaturized end-fire antenna with improved low-frequency radiation performance (RP) is proposed for time- domain applications. Through a novel resistive loading (RL) method, the proposed time-domain antenna (TDA) has a compact size of 0.176 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> ) × 0.156 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W</i> ), and improved low-frequency RP. Note that, this improvement does not mean the improvement of radiation efficiency, but means the enhancement of the radiation in forward and the reduction of the radiation in backward. Furthermore, the size of the proposed TDA is reduced by 78% as compared with the traditional antipodal Vivaldi antenna (AVA). In order to provide a certain reference for the design of end-fire TDAs, the mechanism of the novel RL technique is explored according to the design. Measured results show that the bandwidth of the proposed TDA is 0.168 ∼ 3 GHz (179%). Due to the compact size and good time-domain performance, the proposed TDA can be a good candidate for time-domain applications such as ground penetrating radar (GPR), Through-Wall Radar (TWR) and high-power pulsed source (HPS). Meanwhile, the novel RL technique can be a prior solution for the miniaturization and low-frequency RP improvement for end-fire TDAs.

Structural and optical analyses for InGaN-based red micro-LED

This study presents a comprehensive analysis of the structural and optical properties of an InGaN-based red micro-LED with a high density of V-shaped pits, offering insights for enhancing emission efficiency. The presence of V-shaped pits is considered advantageous in reducing non-radiative recombination. Furthermore, to systematically investigate the properties of localized states, we conducted temperature-dependent photoluminescence (PL). The results of PL measurements indicate that deep localization in the red double quantum wells can limit carrier escape and improve radiation efficiency. Through a detailed analysis of these results, we extensively investigated the direct impact of epitaxial growth on the efficiency of InGaN red micro-LEDs, thereby laying the foundation for improving efficiency in InGaN-based red micro-LEDs.

A Time-Modulated Antenna Array With Continuous Sideband Spectrum Distribution

Traditional time-modulated antenna arrays (TMAs) usually introduce sideband radiations at a multiple of discrete harmonic frequencies. To improve radiation efficiency of TMAs, various evolutionary algorithms become very popular in sideband suppressions. Apparently, the sideband radiation levels highly depend on the performance of these evolutionary algorithms. To achieve robust sideband suppression through physical designs, a novel pseudorandom hybrid phase–amplitude modulation technique is proposed to distribute the sideband radiation power over a continuous spectrum, rather than only at discrete harmonic frequencies. Following the law of energy conservation, sideband levels (SBLs) in this case naturally become extremely low, which eliminates the difficulty arising in TMAs’ sideband suppressions. Moreover, the novel modulation technique allows the synthesis of scanning beams with ultralow sidelobe levels, and the corresponding time modulation sequences could be directly calculated from analytical formulations. Therefore, evolutionary optimization algorithms are not necessary in the proposed TMA design procedure, which facilitates the real-time on-board calculation with an field-programmable gate array (FPGA) board. As compared with traditional TMAs, the proposed TMA achieves ultralow SBLs ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt; -35.0$ </tex-math></inline-formula> dB) with much fewer time modulation statuses. Numerical and experimental results are presented to demonstrate the effectiveness of the proposed TMA.

Broadband Printed Tapered Slot Antenna Fed by CPW Fulfilled with Planar Artificial Magnetic Conductor for X-Band Operation

A low-profile printed slot antenna (PSA) backed by broadband planar artificial magnetic conductor (AMC) is introduced in this study. Firstly, a suggested PSA with the radiating tapered slots excited by coplanar-waveguide (CPW) is used to expand the bandwidth in the measured range of 9-11 GHz (S11≤ -10 dB). Then, the suggested planar AMC surface as the ground plane of the antenna is inserted into the PSA to gain improved radiation efficiency. The realized result from the PSA with the 9×9 planar AMC array exhibits -10 dB measured impedance bandwidth from 6.63 to 13.73 GHz (70%). The suggested PSA with AMC compared to the PSA without AMC exhibits a size reduction of 60%, enhanced bandwidth of 50%, and excellent impedance matching with a minimum value of almost -40 dB. The novel AMC unit cell is realized to operate at 10.14 GHz with an AMC bandwidth of 8-12.35 GHz (43.1%) for X-band operation. Besides, by loading a periodic AMC unit cells into PSA, a high gain of more than 11 dBi with uni-directional radiation patterns is achieved.

A Cancelling-Blocking structure for decoupling of microstrip antenna array

In this work, a cancelling-blocking structure (CBS) for decoupling of microstrip antennas was proposed, which can reduce the coupling between arbitrary elements of a one-dimensional E-plane antenna. Results demonstrate the optimized active VSWR and improved radiation efficiency. The cancelling-type decoupling structure consists of a plurality of electrically small metal sheet arrays printed on the dielectric above the antenna. The blocking-type decoupling structure means that each element uses independent dielectric and ground plane to cut off the coupling current propagation path. Firstly, the decoupling principle of the cancelling-type decoupling structure was deduced, and the decoupling conditions were obtained. Then, the mechanism of the surface wave in the antenna array was qualitatively analyzed, and the applicable conditions of the blocking-type decoupling structure were deduced. To verify the proposed structure, a 1×8 E-plane antenna with the designed CBS was modeled. Simulation results manifested that a mutual coupling reduction of more than 10 dB in 1.2-1.3 GHz was achieved, and the active VSWR was below 2.0 over the range of ±60° scan angle.

Dual-Mode Substrate Wave Cancellation in a 120 GHz 2 × 2 On-Chip Dipole Array

In this article we present the design of a 120 GHz 2 <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> 2 dipole array in a 130 nm SiGe technology, which employs dual mode substrate wave cancellation to improve radiation efficiency and to avoid uncontrolled radiation from the chip edges. We show a systematic analysis of the involved dielectric slab modes TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and their effects on the radiation pattern and efficiency. Based on this, the position and orientation of the array elements are derived for optimal cancellation of substrate waves and different feeding techniques are compared. The dipole array shows a measured realized gain of 1 dBi [including ground signal ground (GSG)-pad, Balun, and matching-capacitor, all on-chip], an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{11}$ </tex-math></inline-formula> -bandwidth of 18 GHz, and a realized gain bandwidth of 16 GHz. Very good correlation between simulations and measurements is achieved through careful modeling of the probe effects. The presented results provide useful insight on the design of on-chip dipole arrays for future millimeter-wave applications in standard SiGe or CMOS technologies.

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

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

Improvement of Radiation Efficiency for Platform-Mounted Small Antenna by Evaluation of Characteristic Mode with Metal Casing Using Infinitesimal Dipole

Improvement of Radiation Efficiency for Platform-Mounted Small Antenna by Evaluation of Characteristic Mode with Metal Casing Using Infinitesimal Dipole

A portable non-invasive microwave based head imaging system using compact metamaterial loaded 3D unidirectional antenna for stroke detection

A metamaterial (MTM) loaded compact three-dimensional antenna is presented for the portable, low-cost, non-invasive microwave head imaging system. The antenna has two slotted dipole elements with finite arrays of MTM unit cell and a folded parasitic patch that attains directional radiation patterns with 80% of fractional bandwidth. The operating frequency of the antenna is 1.95–4.5 GHz. The optimization of MTM unit cell is performed to increase the operational bandwidth, realized gain, and efficiency of the antenna within the frequency regime. It is also explored to improve radiation efficiency and gain when placed to head proximity. One-dimensional mathematical modelling is analyzed to precisely estimate the power distribution that validates the performance of the proposed antenna. To verify the imaging capability of the proposed system, an array of 9 antennas and a realistic three-dimensional tissue-emulating experimental semi-solid head phantom are fabricated and measured. The backscattered signal is collected from different antenna positions and processed by the updated Iterative Correction of Coherence Factor Delay-Multiply-and-Sum beamforming algorithm to reconstruct the hemorrhage images. The reconstructed images in simulation and experimental environment demonstrate the feasibility of the proposed system as a portable platform to successfully detect and locate the hemorrhages inside the brain.

Silicon Wearable Body Area Antenna for Speech-Enhanced IoT and Nanomedical Applications

We propose in this paper a reduction in the size of wearable antennas on silicon (Si) for medicinal frameworks and Internet of things (IoT) in various nanoapplications. This research also introduces one more type of dynamic patch antenna designed in favor of speech-enhanced healthcare applications. The most significant impediment to the adoption of smart correspondence and medical services frameworks is voice-enabled IoT. The primary objective of a body area network (BAN) is to give ceaselessly clinical information to the doctors. Actually, wireless body area network is flexible, dense, trivial, and less expensive. On the other hand, the main disadvantage is low efficiency for small printed antenna. Microstrip silicon antenna recurrence is changed because of ecological conditions, distinctive reception apparatus areas, and diverse framework activity modes. By using tunable antenna, the efficiency of bandwidth usage can be increased. Amplifiers are associated with the feed line of antenna in order to build its dynamic range. In this study, a dynamic polarized antenna is constructed, analysed, and attempted for fabrication. The gain of the antenna is 13 ± 2 dB for the frequency range of 390 to 610 MHz. The output of the polarized antenna is roughly 19 dBm. At different environmental conditions, the performance and ability to control the antenna could vary. To achieve stable performance, we have used varactor diode and voltage-controlled diode. This silicon wearable antenna can be fabricated and tested for many medical applications like health monitoring system and pacemakers. Furthermore, micromachining techniques can be used to lower the practical dielectric constant of silicon and hence improve radiation efficiency.

CPW-fed printed tapered slot antenna loaded by a wideband stacked artificial magnetic conductor with a progressed performance

AbstractA low profile printed slot antenna (PSA) backed by broadband stacked artificial magnetic conductor (AMC) is introduced in this study. First, a suggested PSA with the radiating tapered slots excited by coplanar-waveguide (CPW) is used to expand the bandwidth in the measured range of 9.05–10.95 GHz (S11 ≤ −10 dB). Then, the suggested stacked AMC surface as the ground plane of the antenna is inserted into the PSA to gain improved radiation efficiency. The realized result from the PSA with the 11 × 17 stacked AMC array exhibits −10 dB measured impedance bandwidth from 6.97 to 13.34 GHz (62.73%). The suggested PSA with AMC compared to the PSA without AMC exhibits a size reduction of 52%, enhanced bandwidth of almost 44%, and excellent impedance matching with uni-directional radiation patterns. The novel AMC unit cell is realized based on the recognized method of stacked elements. The stacked AMC design operates at 10.63 GHz with an AMC bandwidth of 8–12.84 GHz (45.8%) for X-band operation. Besides, by introducing a specific method based on the reflection results of the equivalent waveguide feed, the number of AMC unit cells is investigated to obtain an optimal AMC array. In this approach, an equivalent waveguide feed corresponding to the center operating frequency is considered to choose the number of AMC array reflector.

High gain, high isolation, and low‐profile two‐element MIMO array loaded by the Giuseppe Peano AMC reflector for wireless communication systems

A low-profile printed dipole antenna (PDA) backed by a broadband Giuseppe Peano fractal artificial magnetic conductor (AMC) is introduced for wireless communications. A suggested PDA with a pair of microstrip dipoles excited by an E-shaped microstrip feedline is used to expand the bandwidth range of 5.5–6.96 GHz (S11 ≤ −10 dB). Then, the suggested Giuseppe Peano fractal AMC surface as a reflector of the antenna is inserted into the PDA to improve radiation efficiency. The PDA with the 4 × 4 Giuseppe Peano AMC array exhibits −10 dB measured impedance bandwidth from 4.25 to 7.10 GHz (50.2%) for the wireless local area network and worldwide interoperability for microwave access (WiMAX) applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 50.5%, enhanced gain up to 8.2 dBi, and excellent impedance matching (at least −19 dB) with uni-directional radiation patterns. The novel AMC unit cell is realized based on the Giuseppe Peano fractal patch to operate at 6.10 GHz with an AMC bandwidth of 5.15–7.10 GHz (32%). Besides, by loading a 4 × 8 AMC reflector into the two-element array with diverse polarisations, a low profile wideband printed structure with enhanced radiation properties is achieved. The measured results show the broad bandwidths from 4.3 to 7.05 GHz for two elements with enhanced gains and good isolations between the elements (more than 28.5 dB) for multiple-input multiple-output (MIMO) systems.

Gain and Bandwidth Improvement of a Cylindrical Dielectric Resonator Antenna (CDRA) by Using of Metamaterial Structures

Using metamaterials on the top of the antenna’s accordance to magneto-dielectric superstrate and near zero refraction index theories causes improvement of radiation efficiency and gain of antennas. In this article, two novel metamaterial unit cells are proposed for gain and bandwidth improvement of Cylindrical Dielectric Resonator Antenna (CDRA). The first metamaterial unit cell is a negative magnetic structure including two rings implemented on both sides of RT/doroid 5880 substrate with dielectric constant of 2.2. Besides, the second metamaterial unit cell is a Double Negative Structure (DNG) realized consisting of two rings printed in one side and a thin wire in other side of RT/doroid 5880 substrate. Two 7 7 arrays of proposed unit cells are considered and used as superstrate layers on the top of a CDRA. Also, the CDRA is made of RT/doroid 6010 material with dielectric constant of 10.2 working at the frequency of 10 GHz. Using proposed metamaterial structures as superstrate layers on the top of the CDRA causes gain and bandwidth improvement up to 3.3 dB and 4.8%, respectively. CDRA in the presence of proposed metamaterial superstrates are analyzed using a 3D full-wave simulator.

Thermal-Assisted UV-Photon Irradiation to Improve Crystallization and Luminescence Efficiency of ZnO

Defect manipulation plays an important role in regulating luminescence efficiency and electric performance of wide bandgap semiconductor devices. ZnO possesses complex defects, resulting in a bottleneck for p-type doping due to self-compensation. In this article, we propose a strategy to manipulate the defects in ZnO microwires (MWs) via thermal-assisted UV-photon irradiation. With this strategy, the photoluminescence (PL) and electroluminescence (EL) of the near band edge emission are enhanced. The improvement in radiation efficiency is attributed to the recrystallization of the ZnO MWs, by which the oxygen vacancy and zinc interstitial defects are suppressed. The combination of UV photo-chemical and thermal quenching for defect regulation is confirmed, for the first time, by PL and EL spectra. The work provides insights into defect engineering for luminescence efficiency improvement in wide bandgap semiconductor devices.

A Whole Closed Space Intrinsically Safe GPR System for Detection of Geological Hazard Sources in Coal Mines

Detailed detection of geological hazard sources is an important and yet challenging problem that remains unsolved. In this letter, we propose a whole closed space intrinsically safe Ground Penetrating Radar (GPR) system for geological hazard detection in coal mine roadway. Compared with many existing GPRs for half-space, this GPR system is characterized by achieving a stable radiation pattern and improved gain throughout the bandwidth. The improved performance for the system is achieved by the newly microwave front end design, adding round corners on the antenna radiation surface to improve radiation efficiency, designing resistive loading for better impedance matching, and optimizing shielding cavity dimensions to eliminate environmental interference. For design validation, a field experiment in mine roadway conditions is conducted, and the results show that the developed system has a good performance in mining roadway with depth detection accuracy at 0.5 m and direction detection accuracy at 1.5 m.

Radiation Efficiency Enhancement of Graphene Plasmonic Devices Using Matching Circuits

In the present work, the radiation properties of a graphene plasmonic patch antenna are investigated and enhanced in terms of efficiency, utilizing circuit-matching techniques. Initially, the reflection coefficient of graphene surface waves due to discontinuities is studied, while the power flow towards free-space is numerically extracted. This analysis indicates that the radiated power is increased for higher values of the chemical potential, although the surface wave is weakly confined and prone to degradation due to interference. For this reason, a graphene sheet that supports strongly confined surface waves is terminated via a matching layer, in order to enhance the radiating power. In particular, the matching layer consists of an appropriately selected larger chemical potential value, in order to minimize the reflection coefficient and boost the radiation performance. The numerical investigation of this setup validates the upgraded performance, since the radiating power is significantly increased. Then, a realistic setup that includes a graphene patch antenna is examined numerically, proving the augmentation of the radiation efficiency when the matching layer is utilized. Finally, the latter is designed with a graded increment in the chemical potential, and the computational analysis highlights the significant enhancement of the graphene plasmonic antenna gain towards the desired direction. Consequently, a more reliable framework for wireless communications between plasmonic devices at THz frequencies is established, which corresponds to the practical significance of the proposed methodology for improved radiation efficiency. All numerical results are extracted by means of an efficient modification of the Finite-Difference Time-Domain (FDTD) scheme, which models graphene accurately.

A tightly coupled dipole array used for radiation power improvement on finite radiation aperture

Radiation power of an electromagnetic wave plays a decisive role in its transmission distance. Traditionally, the radiation power can be improved by expanding the radiation aperture size of the antenna array or increasing input power of the unit cell. However, the radiation aperture size is always restricted by assembly space. The input power improvement of the unit cell is always limited by the signal source. It is difficult to improve radiation power on a finite radiation aperture. However, the radiation power on a finite radiation aperture is related closely to the number of antenna elements and the radiation efficiency of the antenna array. It is useful to arrange more elements and improve radiation efficiency of the antenna array to improve the radiation power on a finite radiation aperture. Wideband wide-angle scanning phased array is able to make full use of a finite radiation aperture. The wide-angle scanning properties make it possible for the radiated power to cover a wide area. In this paper, a compact wideband wide-angle scanning tightly coupled dipole array (TCDA) is proposed. A high permittivity substrate and compact wideband balun are used for miniaturizing the antenna array. The period of the unit cell is only 0.144&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;high&lt;/sub&gt; × 0.144&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;high&lt;/sub&gt; (&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;high&lt;/sub&gt; is the wavelength at the highest operation frequency in free space). Parameters of the balun are optimized to improve impedance matching between the balun and the antenna array. Two bilateral frequency selective surfaces (FSSs) are used to replace traditional dielectric superstrate to improve the impedance matching between the antenna array and free space. A low-loss dielectric substrate is used to reduce dielectric loss of the antenna array. In these ways, the radiation efficiency is greatly improved. The simulation results show that the proposed antenna array operates at 1.7–5.4 GHz (3.2:1) while scanning up to 65° in the E plane, 45° in the H plane and 60° in the D plane with following a rigorous impedance matching criterion (active VSWR &lt; 2). A 16 × 16 prototype array is fabricated and measured. Good agreement is achieved between the simulation results and the measurement results. Compared with the designs in the literature, the proposed antenna array has an excellent performance in radiation power on a finite radiation aperture.

Millimeter-Wave Planar Antenna Array Based on Modified Bulk Silicon Micromachining Technology

In this communication, a planar antenna array is proposed in millimeter-wave bands by using a modified bulk silicon micromachining technology. The proposed antenna array is designed and fabricated based on air-filled microstrip line structures. By periodically blocking the microstrip line, fringing electric fields along the microstrip lines are excited in phase, which contributes to achieving high gain performance with a relatively compact feeding structure. Moreover, the proposed antenna array is designed and fabricated by a modified bulk silicon micromachining technology. The process is quite suitable for designing low loss antennas in millimeter-wave bands. In the process, the silicon wafers are deeply etched and gold-plated. As a result, microstrip line structures in the proposed antenna array are filled with air medium, which mitigates dielectric loss and improves radiation efficiency. A prototype of the proposed antenna array is fabricated and tested to verify the design strategy. The dimension of the antenna array is 49.40 × 20.00 × 0.75 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The simulated -10 dB bandwidth is 58.8-59.7 GHz and the measured bandwidth is 58.8-59.5 GHz. In the operating band, the maximum simulated gain of the proposed antenna is 19.8 dBi and the minimum simulated gain is 18.3 dBi. The measurement results illustrate that the maximum gain of the proposed antenna array is 18.8 dBi and the minimum gain is 17.0 dBi.