Broadside Radiation Pattern Research Articles

A Single-Layer Miniaturized Patch Antenna Based on Coupled Microstrips

A new method to miniaturize patch antennas is presented by using coupled microstrip patches. A design example is given at 8.45 GHz. The resultant patch antenna has an electrical size of 0.146 × 0.146 × 0.04 λ 03, which is about 60% area reduction with respect to a conventional patch antenna. The miniaturized patch antenna shows similar broadside radiation patterns and a lower cross-polarization level as compared with the conventional one. It exhibits a realized gain of 5.4 dBi with the half-power beamwidths of 107° in the E-plane and 87° in the H-plane, respectively. Both simulated and measured results demonstrate that the miniaturized patch antenna exhibits excellent impedance and radiation characteristics and is a promising candidate for highly integrated wireless systems.

Modified Designs of U-slot Cut Microstrip Antennas for Wider Bandwidth

Wideband design of coaxially fed U-slot cut patch is a widely reported configuration. It yields a bandwidth of 20–25% on a substrate thickness of 0.06–0.07 λg. In all the reported designs, narrower U-slot has been used as it yields required impedance matching to achieve the wideband response. In this paper, initially a detailed study is presented to explain the effects of employing wider U-slot in the rectangular patch to achieve the wider bandwidth. A further modified design of U-slot cut rectangular microstrip antenna is presented, to achieve the impedance matching using a wider U-slot. The modifications in the U-slot cut patch yield optimum possible impedance around the patch TM10 resonant mode that optimizes the loop position inside VSWR = 2 circle, to achieve the maximum bandwidth. Variations using different values of the vertical U-slot lengths have been investigated. In all those variations, impedance bandwidth in the range of 26–30% is achieved in the 950 MHz frequency band, which is 5% higher when compared with narrow U-slot designs. Furthermore, a pair of rectangular slot-cut design of modified U-slot cut antenna is presented, which yields further 5% increment in the bandwidth. Similar designs with circular patch are also proposed which yield more than 5% increase in the bandwidth. In addition to the bandwidth increment, the proposed designs yield nearly 20% reduction in the patch copper area. Proposed antennas yield a broadside radiation pattern with a peak gain of 9 dBi.

Millimeter-wave multi-mode circular antenna array for uni-cast multi-cast and OAM communication

This paper investigates uni-/multi-cast and orbital angular momentum (OAM) mode data transmission in orthogonal directions by the utilization of a new circular antenna array, operating at 28 GHz. In the horizontal plane the proposed antenna array operates as multimode transmitter (i.e., it provides broad-, uni- and/or multi-cast communication), while in the vertical direction OAM transmission occurs (i.e., it is capable of generating up to 15 spatially orthogonal OAM modes). Antenna array is designed using twelve, low-complexity, electromagnetically coupled microstrip patch antennas with high radiation efficiency. Each of these can transmit power of equivalent order of magnitude in both horizontal (i.e., broadside radiation pattern) and vertical direction (i.e., endfire radiation pattern) over electromagnetic waves of orthogonal electric components. This property leads to the formation of uni-/multi-cast and OAM modes in the horizontal plane and vertical direction, respectively. Antenna was tested through full-wave electromagnetic analysis and measurements in terms of impedance matching, mutual coupling and radiation pattern: good agreement between simulated and measurement results was observed. Specifically, it presents up to 8.65 dBi and 6.48 dBi realized gain under the uni-cast (in the horizontal plane) and OAM mode (in the vertical plane), respectively. The proposed antenna array is perfect candidate for high spectral efficiency data transmission for 5G and beyond wireless applications, where orthogonality in communication links and OAM multiplexing is a requirement.

Broadband coplanar waveguide‐fed stub loaded pot shape E‐textile antenna equipped with perfect electric conductor

In this paper, a coplanar waveguide (CPW) fed pot-shaped electronic textile (E-textile) antenna aided by rectangular ring ground plane has been proposed. The textile patch in pot form is designed by cutting triangular slots on the non-radiating edges of the rectangular patch, which yields a broadband of 6.45 GHz. The measured antenna impedance bandwidth is from 2.15 to 8.6 GHz with a peak gain of 10.7 dB on fabricated human tissue muscle equivalent phantom model. The proposed antenna exhibits a broadside radiation pattern from 2.15 GHz to less than 6 GHz and conical radiation pattern from 6 GHz to 8.6 GHz covering wide impedance matching bandwidth (S11 ≤ −10 dB) of 120% for dual-mode off and on-body communication. In CPW fed technique, the back radiation from the antenna to on body is reduced by using a perfect electric conductor. For wearable applications, considering human safety concern the specific absorption rate levels are maintained, that is less than 1.6 W/kg limit over the operating bandwidth according to IEEE C95.1-1999 standard averaged over 1 g of tissue model.

Polarization conversion metasurface design based on characteristic mode rotation and its application into wideband and miniature antennas with a low radar cross section.

In this paper, a characteristic mode rotation (CMR) method has been proposed to design a compact metasurface antenna with a low radar cross section (RCS) in a wideband. In the proposed CMR method, the incident wave dependent complex characteristic currents corresponding to the dominant characteristic modes solved by the characteristic mode method (CMM) are calculated. With the direction of the superposition of the complex characteristic currents orthogonal to that of the incident electric field in the CMR method, the metasurface subarray with wideband polarization conversion characteristic is designed. By arranging the metasurface subarray in a rotation way, a metasurface array with a compact size of 1.28λ0×1.28λ0 is designed for wideband RCS reduction. A miniature circle patch antenna is integrated with the metasurface array to achieve not only good radiation performance but also low observability for the in-band and the out-of-band of the antenna. Simulated and measured results demonstrate that the proposed miniature metasurface antenna designed by the CMR method has a good broadside radiation pattern, a maximal gain of 10.75 dB, and a -10 dB RCS reduction characteristic in the wide band of 6∼20.7 GHz with a fractional band of 110%.

Quad-Polarization-Reconfigurable Antenna With a Compact and Switchable Feed

A reconfigurable antenna with a compact size and quad-polarization reconfigurability is presented. By employing a switchable feed scheme, the antenna can operate at single-fed and dual-fed modes. At single-fed mode, the feed structure allows output ports switching to produce the excitations for either slant +45° or -45° linear polarization (LP). At dual-fed mode, it serves as a switchable phase-shifting power splitter for generating left-hand circular polarization (LHCP) or right-hand circular polarization (RHCP). To realize a simple and space-saving configuration, the antenna makes efficient use of the proposed feed structure, which is highly shared among the four polarization states. Measured results show that the antenna exhibits operating bandwidths of 230 and 260 MHz at circular polarization CP and LP states, respectively. Moreover, stable broadside radiation patterns as well as moderate gains could also be obtained.

A Multiplexing Filtering Antenna

In this communication, a compact, highly integrated multiplexing filtering antenna operating at 4.7/5.2/6.0/6.6 GHz is proposed for the first time. Different from traditional antennas, the proposed antenna has one shared radiator but four ports working in different frequency bands, and thus, it can simultaneously support four different transmission channels. The proposed multiplexing antenna is composed of a patch with a U-shaped slot, two substrate integrated waveguide (SIW) cavities, and four resonator-based frequency-selective paths. The resonator-based paths can not only enhance the interchannel isolations but also improve the impedance bandwidth. The design principles and the methods of controlling the four operating bands are studied. Measurement results agree reasonably well with the simulations, showing four channels from 4.5 to 4.8 GHz, 5.1 to 5.3 GHz, 5.85 to 6.3 GHz, and 6.4 to 6.6 GHz, respectively. The antenna also exhibits high isolation of over 25 dB between the channels. In addition, the proposed antenna has a consistent broadside radiation pattern and polarization in the four bands, and manifesting the proposed multiplexing filtering antenna can be a promising candidate for multiservice wireless communication systems.

A Wideband Pattern Diversity Antenna With a Low Profile Based on Metasurface

In this letter, a low-profile wideband pattern diversity antenna based on metasurface (MTS) is proposed. Initially, based on the theory of characteristic mode (TCM), the two adjacent intrinsic modes, which correspond to the broadside and conical radiation pattern, respectively, are exploited to realize a wideband pattern diversity characteristic under a low profile. Then, by analyzing the modal current distribution on the MTS, the optimal locations, orientations and relative phases of the four L-shaped feeding probes are determined to excite the above two modes. However, the in-band high-order modes (HOMs) introduced by the feeding structure will deteriorate the radiation pattern. Therefore, chamfering corners on the MTS is used to suppress the HOMs for radiation pattern improvement. Finally, by combining TCM and MTS, the modes are manipulated to achieve a pattern diversity antenna with an extremely low profile of 0.06 λ0 (the free-space wavelength at the center frequency) and an isolation of better than 38 dB, which also maintains an operating bandwidth of 20.24%. Based on these excellent performances, the proposed antenna is an attractive solution for pattern diversity applications requiring low profile, especially in unmanned aerial vehicle communications.

A Fully Transparent Wideband Water Patch Antenna With L-Shaped Feed

A wideband and fully optically-transparent water patch antenna is proposed. Both the patch and the ground plane are made of distilled water. Different from the previous water patch antennas, this proposed design features the utilization of an L-shaped distilled water probe as the feed structure. Thus, substantial improvement in the transparency is achieved. To excite the water patch antenna, a short inner probe of a coaxial cable is inserted into the water probe. The electromagnetic (EM) waves excited by the inner probe can propagate along the L-shaped water probe and also resonant in the middle substrate (air) under the water patch, causing radiation into the free space. The L-shaped water probe can significantly improve the impedance bandwidth, which has the same function as the reported L-shaped metallic probe. The results show that the proposed water patch antenna has a wide impedance bandwidth of 42.6% (from 1.48 to 2.28 GHz with $|{\mathrm{ S}}_{11}| dB), a gain up to 7.5 dBi, a radiation efficiency up to 67% and broadside radiation pattern across the bandwidth. In addition, some parametric studies on the distilled water probe have been carried out for the design purpose. The proposed water patch antenna has confirmed the possibility of designing a patch antenna fully made of liquid or solid dielectric materials with high dielectric constant such as water, instead of using metal.

Wideband via-Loaded Cylindrical Open-Ended SIW Cavity Antenna

A composite cavity-based antenna is proposed and presented in this work. Three kinds of modes of the composite structure are involved to obtain a wide bandwidth: the ${\mathrm {TE}}_{11 {\scriptstyle {}^{\scriptstyle 1}}\hspace {-0.224em}/\hspace {-0.112em}{\scriptstyle 2} }$ cavity mode of a cylindrical open-ended substrate integrated waveguide cavity, the odd TEM mode generated by loading two rectangular via holes inside the cavity, and the higher-order loop modes (L3 and L5) of a circular ring detached from the cavity by a circumferential slot located at the cavity’s side wall. In the implementation of the antenna, slot coupling feeding methodology is applied, which also introduces a resonance for the bandwidth enhancement. A simulated fractional impedance bandwidth of 57.3% with $|{\mathrm{ S}}_{11}| dB from 24.9 GHz to 44.9 GHz is achieved ( $|{\mathrm{ S}}_{11}|= -9.7$ dB at $f=27.7$ GHz is ignored). The antenna has a broadside radiation pattern within the operating frequency band and a maximum simulated broadside gain of 10.6 dBi at ${f}=27$ GHz. Multi-layer technique and metallized via holes processing, which become commercial nowadays, are two critical techniques of the presented antenna. The simple structure is benefit of the fabrication and the integration with other planar front-end circuits. The antenna is fabricated and experimentally verified. A small difference is observed between the measurement and the simulation. A measured fractional bandwidth of 52% from 27 GHz to 46 GHz ( $|{\mathrm{ S}}_{11}|= -9$ dB at ${f}=29$ GHz is ignored) and a measured maximum broadside gain of 9.5 dBi are achieved.

Ultra-Wideband Patch Antenna Array With an Inclined Proximity Coupled Feed for Small Unmanned Aircraft RADAR Applications

This paper presents the design of a lightweight and compact patch antenna array with an inclined proximity coupled feed. The antenna array is designed for operation on a small unmanned aircraft system (sUAS) with an ultra-wideband (UWB) radar for remote sensing of soil moisture and snow. To achieve UWB impedance matching, the design utilizes an inclined wide feed and inter-element coupling. A 3-D printed base (polylactic acid) is used to support the feed structure. The antenna array operates over a 2.5 GHz -4.5 GHz frequency (57.2% bandwidth) range, and its weight is 112 grams. A prototype 2 × 4 element array is fabricated and tested. The antenna array has an 88.2% average radiation efficiency and a 13.2 dBi average realized gain over the desired frequency band with broadside and stable radiation pattern.

A Novel Dual-Polarized Wideband and Miniaturized Low Profile Magneto-Electric Dipole Antenna Array for mmWave 5G Applications

A Ka-band dual-polarized low profile magneto-electric (ME) dipole antenna with wide operational bandwidth is proposed in this paper. A thin substrate with two-stage meandered vias is utilized for realization of the proposed antenna. The meandered vias aid in compensation of phase difference caused due to utilization of thin substrate. The thickness of proposed antenna is reduced from 0.25 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> to 0.11 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> by using these two-stage meandered vias. The low profile antenna topology results in bandwidth reduction which is neutralized by introducing asymmetric slots in the ground plane. Shorting pins are inserted for elimination of higher order TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> mode of Ka-band that results in a uniform broadside radiation pattern due to excitation of fundamental TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode. The proposed antenna covers whole Ka-band with operating frequencies from 26 - 42 GHz. A 1 × 4 antenna array is also designed and fabricated with a reasonable gain of 12.06 dBi and stable radiation patterns. Simulated and measurement results are presented with detailed justification.

A Low-Profile Dielectric Resonator Antenna With Compact-Size and Wide Bandwidth by Using Metasurface

A dielectric resonator antenna (DRA) with the loading of metasurface (MS) is proposed for low-profile, wide-bandwidth and compact-size. Firstly, an MS structure consisting of $6\times6$ periodic metallic patch cells is loaded above the DRA. It aims to excite an additional TM surface wave above the fundamental TE111 mode of the rectangular DRA. Then, the shorting walls are printed on two sides of the dielectric, thus moving down the operating frequency with respect to its TM surface wave mode. As such, the bandwidth of the antenna is significantly widened with compact-size under the operation of TE111 and TM surface wave modes. Finally, the proposed DRA with enhanced performance is fabricated and tested. The results show that an impedance bandwidth of the antenna is dramatically increased to about 17.2%, covering the frequency range from 1.75 to 2.08 GHz, which is about 9.6 times wider than the traditional DRA at the same thickness (1.8%). Besides, it still maintains the broadside radiation pattern with stable gain of around 6.6 dBi and fairly low cross polarizations of below −26 dB. Particularly, the overall size of the radiator still maintains as small as about $0.32\lambda _{0} \times 0.32\lambda _{0} \times 0.044\lambda _{0}$ . It should be noted that the analysis of the antenna is carried out by using Ansys HFSS software version 14.0 and ADS 2011.

Vertically Polarized Quasi-Yagi MIMO Antenna for 5G N78 Band Application

In this study, a three-port vertically polarized Quasi-Yagi Multiple-Input-Multiple-Output (MIMO) antenna system with pattern diversity is proposed for 5G N78 band application. All the three ports, which are sequentially rotated by 120°, are integrated together on a circle patch. Each antenna element is fed by a probe and an annular slot etched on the patch which works as a capacitor to counteract the inductance effect introduced by the feeding probe and the nearby shorting posts. A patch-like broadside radiation pattern is generated for each element. By introducing a novel Γ-shaped metal plate for each element, the radiation beam could be tilted and deviate from the z axis by around +30° to suit the diversity application demand. Good isolation is achieved by introducing a metal post between every two ports, which well suppresses the mutual coupling induced by the current between the ports. The working principle of the proposed MIMO antenna is theoretically illustrated in detail and experimentally verified. The Proposed antenna occupies a cylindrical volume of π × 0.33 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> × 0.14 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , where λ0 represents the free space wavelength at the center frequency of the operating band. The measured overlapping bandwidth covers the N78 band (3.3-3.8 GHz) with |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB for the three antenna elements. The proposed antenna offers attractive features including a shared radiation aperture, pattern diversity, good isolation (≤ 20 dB) good gain (≥ 8.2 dBi), low field envelope correlation coefficient value (≤ 0.001), and high radiation efficiency (≥ 74%).

Designing Efficient Phase-Gradient Metasurfaces for Near-Field Meta-Steering Systems

We investigate the aptness of various 4 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> order (90°) rotationally symmetric phase-transforming cells for the upper phase-gradient metasurface, which always receives an oblique incidence wave from the lower metasurface in a Near-Field Meta-Steering system. A comprehensive study on the behavior of various phase-transforming cells and corresponding supercells when a rotating oblique plane wave impinges on them is presented. First, we select the supercell with high transmission in the desired output Floquet modes, for both TE and TM input modes, when an oblique incidence wave is rotated. The selected supercell is then optimized using Floquet analysis in conjunction with particle swarm optimization (PSO). All the undesired modes are successfully suppressed below -32 dB in the optimized supercell, and the predicted broadside radiation pattern is free of spurious grating lobes. A Near-Field Meta-Steering system with an aperture diameter of 7.3λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (110mm @ 20 GHz) is presented. It has a pair of optimized phase-gradient metasurfaces and a dipole antenna array. A maximum peak directivity of 24.2 dB is achieved when the beam is in the broadside direction. The proposed steering system is capable of scanning a conical range with an apex angle of 126° when a 6 dB reduction in peak directivity is allowed. For a 3 dB variation in the peak directivity, the corresponding apex angle is 103°.

Design of Wideband Linearly Polarized 3-Bit Transmit-Array Antenna With Polarization Rotation Unit Cell

The millimeter-wave (mm-wave) band is expected to be the optimal solution for future wireless communication systems as it provides a wide bandwidth, which enhancing data transmission rate. Therefore, high-directive antennas, principal elements for mm-wave wireless communications, are used at the mm-wave band as they can overcome the negative effect of high path losses. A transmit-array antenna (TA) operates at the mm-wave band (around 28 GHz) with high aperture efficiency, high gain, wide bandwidth, and low-profile TA surface has been designed. Basically, the aperture efficiency of the TA depends on the unit cell (UC) characteristics, and feed antenna radiation pattern. Therefore, the UC elements designed based on capacitive differential feeding and true time delay techniques, as a result the designed UC has a wide bandwidth with a stable broadside radiation pattern, high cross-polarization discrimination and a full phase range (0-360°) and a maximum element loss of 0.5 dB. Moreover, the designed UC rotates the polarization of linearly polarized electromagnetic (EM) wave to its orthogonal direction with high efficiency, a polarization conversion ratio higher than 0.9 is achieved within the operating frequency band. The used techniques to design the proposed UC have a significant effect on TA antenna performance, in terms of gain and bandwidth. The TA antenna surface and the feeding antenna have been designed and fabricated. The maximum gain is 31.15 dBi. The 1 dB gain bandwidth is 12.7% while the 3 dB gain bandwidth is 21% around 28 GHz. The aperture efficiency is better than 50% and the cross-polarization level is less than -37 dB, on the frequency range from 25 to 31.5 GHz.

Suspended embroidered triangular e-textile broadband antenna loaded with shorting pins

An embroidery triangular e-textile (electronic textile) antenna with shorting pins is proposed in this paper for broadband response and to increase the on-body efficiency in 5.8 GHz industrial, scientific, and medical (ISM) band. The triangular patch is embroidered with silver coating conductive yarn using a computerised aided embroidery machine. The proper positioning of the shorting pins is selected to tune the fundamental TM10 mode at the desired frequency. The proposed antenna is embroidered on the textile substrate material and is suspended over a slotted ground plane to realize wider bandwidth. The antenna yields measured impedance bandwidth of 210 MHz (5.63–5.84 GHz) for S11 ≤ -10 dB with a peak gain of 4.1 dB in the broadside direction. Furthermore, the radiation efficiency of the antenna is above 65% over the operating bandwidth. The effect of an antenna radiation on the human body is also analysed by evaluating the specific absorption rate (SAR) levels. The broadband embroidery triangular patch antenna with broadside radiation pattern provides the attractive flaunt and best fit device for off body communication.

Patch antenna with circular and rectangular notches and slots for millimeter waves

This manuscript presents Rectangular patch antenna with slots and notches for mm wave. An antenna has dual band with two resonating bands at 24GHz and 39 GHz. First resonating band gives ultra wide band of 27.08% while second resonating band is narrow band. Antenna characteristics have been observed such as radiation pattern, radiation efficiency, impedance and reflection co-efficient. The radiation efficiency of 80% and broadside radiation pattern d has been observed at center frequency. The variation of dielectric constant on the patch has been also observed in achieving dual band. This antenna can be used in various wireless applications such as 5G allocation band of European countries, vehicular communication.

A Broadband Differential-Fed Dual-Polarized Hollow Cylindrical Dielectric Resonator Antenna for 5G Communications.

A broadband differential-fed dual-polarized hollow cylindrical dielectric resonator antenna (DRA) is proposed in this article. It makes use of the HEM111, HEM113, and HEM115 modes of the cylindrical hollow DRA. The proposed DRA is simply fed by two pairs of conducting strips and each pair of strips is provided with the out-of-phase signals. After introducing four disconnected air holes into the DRA, a broadband characteristic is achieved, with little effect on the antenna gain of its higher-order modes. To verify this idea, frosted K9-glass is applied to fabricate the hollow cylindrical DRA. The differential S-parameters, radiation patterns, and antenna gain of the DRA are studied. It is found that the proposed differential-fed dual-polarized DRA is able to provide a broad differential impedance bandwidth of ~68% and a high differential-port isolation better than ~46 dB. Moreover, symmetrical broadside radiation patterns are observed across the whole operating band. The proposed DRA covers the frequency bands including the 5G-n77 (3.4–4.2 GHz), 5G-n79 (4.4–5.0 GHz), WLAN-5.2 GHz (5.15–5.35 GHz), and WLAN-5.8 GHz (5.725–5.825 GHz), which can be used for 5G communications.

Single-Layer Dual-Mode Microstrip Antenna With No Feeding Network for Pattern Diversity Application

A single-layer microstrip patch antenna (MPA) under the operation of TM10 and TM20 modes for pattern diversity application without needing to rely on any feeding network is proposed for the first time in this letter. Initially, when a thorough analysis on mode excitation and inhibition of the MPA was deeply conducted, it demonstrated that its TM10 and TM20 modes could be independently excited by properly placing two coaxial ports underneath the radiating patch; thus, generating the desired broadside and bidirectional radiation patterns, respectively. Then, two sets of shorting pins are inserted below the core radiator, aiming to raise the resonant frequency of its TM10 mode in proximity to that of the TM20 mode. In addition, the maximum input resistances of these dual radiative modes decrease dramatically as f 10 and f 20 increase, which enables good impedance matching. Finally, the proposed MPA is designed, fabricated, and tested to validate the working principle. The results illustrate that this antenna can operate over the overlapping frequency ranges of 5.83–5.89 GHz with an envelope correlation coefficient of lower than 0.015, while keeping its low-profile thickness of 0.045λ0. Due to its unique advantages of low profile, simple structure, and good diversity, the proposed MPA could be a promising option in wireless local area network (WLAN)-related applications.