Showing papers on "Patch antenna published in 2018"

Study on isolation improvement between closely-packed patch antenna arrays based on fractal metamaterial electromagnetic bandgap structures

Abstract: A decoupling metamaterial (MTM) configuration based on fractal electromagnetic-bandgap (EMBG) structure is shown to significantly enhance isolation between transmitting and receiving antenna elements in a closely-packed patch antenna array. The MTM-EMBG structure is cross-shaped assembly with fractal-shaped slots etched in each arm of the cross. The fractals are composed of four interconnected-`Y-shaped' slots that are separated with an inverted-`T-shaped' slot. The MTM-EMBG structure is placed between the individual patch antennas in a 2 × 2 antenna array. Measured results show the average inter-element isolation improvement in the frequency band of interest is 17, 37 and 17 dB between radiation elements #1 & #2, #1 & #3, and #1 & #4, respectively. With the proposed method there is no need for using metallic-via-holes. The proposed array covers the frequency range of 8-9.25 GHz for X-band applications, which corresponds to a fractional-bandwidth of 14.5%. With the proposed method the edge-to-edge gap between adjacent antenna elements can be reduced to 0.5λ 0 with no degradation in the antenna array's radiation gain pattern. Across the array's operating band, the measured gain varies between 4 and 7 dBi, and the radiation efficiency varies from 74.22 and 88.71%. The proposed method is applicable in the implementation of closely-packed patch antenna arrays used in SAR and MIMO systems.

A Flat Dual-Polarized Transformation-Optics Beamscanning Luneburg Lens Antenna Using PCB-Stacked Gradient Index Metamaterials

Abstract: Based on a transformation optics method, a flat compact dual-polarized Luneburg lens antenna is proposed and implemented using the printed-circuit-board-stacked gradient-index metamaterials for beamscanning and multibeam applications at X-bands. The transformed material properties of the planar Luneburg lens are designed with 17-layered permittivity distribution of polynomials. Each layer is discretized into $41 \times 41$ pixels made of broadband and less polarization-dependent unit cells responsible for desired index distributions. The effects of transformation, approximation, and discretization on the lens performance are analyzed comprehensively. Also, to validate the implementation method, a flat Luneburg lens with a thickness of 14.1 mm, a focal length of 28 mm, and an aperture size of $98.9 \times 98.9$ mm2 is designed and tested. A stacked aperture-coupled patch antenna operating at 10 GHz is applied as a feeder. The measured results show that the proposed antenna can operate over a bandwidth of ~20% with an antenna efficiency of 32%, a cross-polarization level of <−17.1 dB, as well as the maximum gain of 15.9/16.35 dBi and a scanning angle of ±32°/±35° for two orthogonal polarizations, respectively. The presented flat Luneburg lens antenna featuring broad bandwidth, high gain, wide scanning angle, and easy fabrication has a high potential in 5G wireless communication, imaging, and remote sensing applications.

High Quality Factor, Ultralow Sintering Temperature Li6B4O9 Microwave Dielectric Ceramics with Ultralow Density for Antenna Substrates

Abstract: Dense Li6B4O9 microwave dielectric ceramics were synthesized at low temperature via solid-state reaction using Li2CO3 and LiBO2. Optimum permittivity ∼ 5.95, quality factor ∼ 41 800 GHz and temperature coefficient of resonant frequency ∼ – 72 ppm/°C were obtained in ceramics sintered at 640 °C with a ultrasmall bulk density ∼2.003 g/cm3 (∼95% relative density, the smallest among all the reported microwave dielectric ceramics). Li6B4O9 ceramics were shown to be chemically compatible with silver electrodes but reacted with aluminum forming Li3AlB2O6 and Li2AlBO4 secondary phases. A prototype patch antenna was fabricated by tape casting and screen printing. The antenna resonated at 4.255 GHz with a bandwidth ∼279 MHz at −10 dB transmission loss (S11) in agreement with simulated results. The Li6B4O9 microwave dielectric ceramic possesses similar microwave dielectric properties to the commercial materials but much lower density and could be a good candidate for both antenna substrate and low-temperature cofire...

Design of a Wideband Omnidirectional Antenna With Characteristic Mode Analysis

Abstract: A low-profile horizontally polarized (HP) omnidirectional metasurface-inspired antenna is presented. To realize HP omnidirectional radiation pattern, the theory of characteristic mode is utilized to facilitate the analysis of three antenna structures. Then, by properly exciting the desired characteristic mode, the antenna with a wide bandwidth and good omnidirectionality, which is based on the modification of the standard patch antenna, is obtained. The simulated results show that the proposed antenna not only can obtain a low profile of 0.06 λ 0 (where λ 0 is the free-space wavelength at 5.2 GHz), but also has a wide operating bandwidth of 16.6%. Finally, the metasurface-inspired antenna is manufactured and the error analysis between the simulated and measured results is also provided. The antenna can be applied to 5G wireless local area network systems.

A Method to Realize Robust Flexible Electronically Tunable Antennas Using Polymer-Embedded Conductive Fabric

Abstract: A new approach to realize robust, flexible, and electronically tunable wearable antennas is presented. Conductive fabric is used to form the conducting parts of the antenna on a polydimethylsiloxane (PDMS) substrate. Then the antenna and the lumped (active and passive) elements, required for electronic tuning and RF choking, are fully encapsulated with additional layers of PDMS. As a concept demonstration, a new frequency-reconfigurable antenna has been designed and fabricated. The details of the prototype manufacturing process are described. Two UWB human muscle equivalent phantoms were also fabricated for testing purposes. Furthermore, the antenna was subjected to several investigations on its RF performance (both in free space and on a flat phantom) and mechanical stability. The latter includes bending tests on several locations on a human-body shaped phantom and washing in a household washing machine. Good agreement between predicted and experimental results (both in free space and on the phantom) is observed, validating the proposed concept. The tests demonstrated that lumped components and other antenna parts remained intact and in working order even under extreme bending (to a bending radius of 28 mm) and after washing, thus maintaining the overall antenna performance including good frequency reconfigurability from 2.3 to 2.68 GHz. To the best of our knowledge, all these features have never been demonstrated in previously published electronically tunable antennas.

Transparent Patch Antenna Using Metal Mesh

Abstract: This communication presents the design, fabrication, and measurement of transparent antennas with metal mesh (MM) for wireless transparent applications such as smart windows, transparent mobile devices, and transparent Internet of Things. The MM was proposed as a transparent electrode with high conductivity in electrical performance, with proper transparency in optical performance, and low fabrication cost compared to a traditional transparent thin film electrode. To analyze the performance of a transparent antenna fabricated by MM, the antennas were designed to operate in the 2.4–2.5 GHz WLAN band (802.11b). The conductive metal of transparent MM patch antennas was designed using a square lattice structure and was fabricated using wired MM with copper wire (0.2–0.5 mm). In addition, micro-MM film consisting of thin copper wire ( $20~\mu \text{m}$ ) was used to fabricate transparent patch antennas. The realized gain, efficiency, front-to-back ratio, and radiation patterns of the transparent MM patch antennas are discussed for various combinations of radiator and ground planes. Overall, the transparent MM patch antennas offer optical transparency, maintain sufficient performance, and could possibly be used in wireless transparent applications.

Microstrip Patch Antennas With Multiple Parasitic Patches and Shorting Vias for Bandwidth Enhancement

Abstract: Two novel microstrip patch antennas with multiple parasitic patches and shorting vias have been presented for the bandwidth enhancement. Based on the conventional triangular patch antenna, two more resonances can be obtained with the introduction of multiple parasitic patches, and consequently, the antenna bandwidth can be broadened. Parametric analysis of the patches has been studied for the verification of bandwidth enhancement. An example of the proposed antenna with multiple parasitic patches is designed, fabricated, and tested. The measured bandwidth with $\vert S_{11}\vert dB ranges from 5.46 to 6.27 GHz (13.8%), and good far-field radiation patterns can be obtained within the frequency band. In addition, two shorting vias are inserted into the above proposed antenna to decrease the input impedance, resulting in further bandwidth enhancement of the antenna. This antenna is fabricated and tested as well, which achieves a measured 10-dB impedance bandwidth of 17.4% from 5.5 to 6.55 GHz.

A High-Gain Circularly Polarized Fabry–Perot Antenna With Wideband Low-RCS Property

Abstract: In this letter, a low radar cross section (RCS) and the high-gain circularly polarized (CP) antenna using a novel linear-to-circular polarization converter is presented. A simple linearly polarized patch antenna rotated 45° relative to x -axis is used as the primary source. The polarization converter is an asymmetrical metastructure composed of different metal patterns printed on the two sides of a dielectric substrate, which can transmit a CP wave. The top-side metallic pattern is an absorbing surface to realize the RCS reduction, while the bottom-side one is a partially reflective surface (PRS). A CP Fabry–Perot resonance cavity is constituted by the PRS and the anisotropic high-impedance surface (HIS) plane to obtain the gain enhancement. The simulation and measured results demonstrate that the proposed antenna exhibits good circular polarization performance in the operating frequency. In addition, the gain of the proposed antenna can be improved by about 3.2 dB at 10.7 GHz, and the RCS can be reduced significantly over a wideband ranging from 4 to 13 GHz for both polarizations, compared with the conventional patch antenna.

Characteristic Mode Design of Wide Band Circularly Polarized Patch Antenna Consisting of H-Shaped Unit Cells

Abstract: This paper proposes a general characteristic mode-based design procedure of simple three steps for wideband circularly polarized (CP) antenna design. First of all, the characteristic mode analysis is carried out to understand the different modes of a proposed antenna geometry without feeding network. Second, modal currents and their corresponding modal fields (radiation patterns) are studied for choosing modes to shape the required radiation pattern. Finally, a suitable feeding structure is chosen to excite the desired modes at the same time owns a good impedance matching. As an example, a CP patch antenna fed with cross-shaped aperture is proposed and designed following the design procedure. Patch consisting of H-shaped unit cells is used as the radiator. Characteristic mode method is applied to analyze the modes of the proposed antenna and explains the property of wide band circular polarization. It is revealed that higher order modes of the patch can be used to achieve circular polarization over a wideband of frequency. The antenna is fabricated using printed circuit techniques. The return loss and radiation properties are measured and compared with simulation results. With the highly coupled units, a wide impedance bandwidth of 38.8% is obtained. Besides, a wide 3-dB axial ratio bandwidth of 14.3% is achieved.

Double-Differential-Fed, Dual-Polarized Patch Antenna With 90 dB Interport RF Isolation for a 2.4 GHz In-Band Full-Duplex Transceiver

Abstract: This letter presents a 2.4 GHz, dual-polarized microstrip patch antenna with extremely high interport isolation for a shared antenna architecture-based in-band full-duplex transceiver. The presented antenna configuration is based on four-ports linearly polarized single radiating element with differential feeding for both transmit $(T_{x})$ and receive $(R_{x})$ operation. The double-differential feeding using two identical 3 dB/180° ring hybrid couplers with nice amplitude and phase balance effectively suppresses the interport RF leakage to achieve very high isolation. The prototype of the proposed antenna architecture is implemented using a 1.6 mm thick general-purpose FR-4 substrate. The implemented antenna provides more than 90 and 80 dB interport RF isolation for 20 and 40 MHz bandwidths, respectively, in addition to more than 98 dB port-to-port peak isolation when measured inside an anechoic chamber. To the best of our knowledge, this is the highest amount of RF isolation reported for a single dual-polarized patch antenna.

Energy Harvesting Using a Low-Cost Rectenna for Internet of Things (IoT) Applications

Abstract: Traditionally employed human-to-human and human-to-machine communication has recently been replaced by a new trend known as the Internet of things (IoT). IoT enables device-to-device communication without any human intervention, hence, offers many challenges. In this paradigm, machine’s self-sustainability due to limited energy capabilities presents a great challenge. Therefore, this paper proposed a low-cost energy harvesting device using rectenna to mitigate the problem in the areas where battery constraint issues arise. So, an energy harvester is designed, optimized, fabricated, and characterized for energy harvesting and IoT applications which simply recycles radio-frequency (RF) energy at 2.4 GHz, from nearby Wi-Fi/WLAN devices and converts them to useful dc power. The physical model comprises of antenna, filters, rectifier, and so on. A rectangular patch antenna is designed and optimized to resonate at 2.4 GHz using the well-known transmission-line model while the band-pass and low-pass filters are designed using lumped components. Schottky diode (HSMS-2820) is used for rectification. The circuit is designed and fabricated using the low-cost FR4 substrate ( ${h}$ = 16 mm and $\varepsilon _{r} = 4.6$ ) having the fabricated dimensions of 285 mm $\times \,\,90$ mm. Universal software radio peripheral and GNU Radio are employed to measure the received RF power, while similar measurements are carried out using R&S spectrum analyzer for validation. The received measured power is −64.4 dBm at the output port of the rectenna circuit. Hence, our design enables a pervasive deployment of self-operable next-generation IoT devices.

A Wideband Differentially Fed Dual-Polarized Stacked Patch Antenna With Tuned Slot Excitations

Abstract: In this communication, a novel wideband differentially fed dual-polarized stacked patch antenna with tuned slot excitations for base station application is proposed. The antenna is composed of a driven patch excited by tuned slot excitations, a parasitic patch to enhance the impedance bandwidth, and a ground plane to obtain unidirectional radiation. Two pairs of the slot excitations etched on the opposite edges of the driven patch are used to obtain dual polarizations. Each tuned slot excitation has an open-ended slot and a $\Gamma $ -shaped feeding line. To connect to the differential circuit easily, a rotated feeding mechanism is adopted. A prototype of the proposed antenna is fabricated and tested. Measured results show that the antenna has a wide differential impedance bandwidth of 49.4% (1.66 to 2.75 GHz) for $\vert \text{S}_{\mathrm{ dd11}}\vert ~f-15 $ dB. In addition, a high differential port isolation of more than 37 dB, a stable radiation pattern with a 3 dB beamwidth of 61°±5°, and a stable gain around 8.7 dBi are obtained within the operational band. The proposed antenna features wideband, high port isolation, and stable gains, and it is a promising candidate for base station systems using differential signals.

A 5G Wideband Patch Antenna With Antisymmetric L-shaped Probe Feeds

Abstract: A dual-polarized patch antenna element fed by a pair of antisymmetric L-shaped probes is proposed. The designed twin L-shaped probe feeding structure is able to introduce feed capacitance to the antenna for broadband operation. The lengths of the two L-shaped probe feeds are identical, but the feeds are antisymmetric. This feeding design can minimize the unwanted radiation from the probe effectively. The dual-polarized antenna can be operated in the frequency band 1580–2750 MHz, which covers the current mobile communication systems, 3G and 4G and higher band frequencies. A prototype with dual slanted ±45° polarization has been fabricated for validation. Both the simulation and measured results show that the proposed antenna has wide bandwidth of 54% (SWR < 2) with desirable directional radiation patterns in the vertical and horizontal planes, as well as high isolation better than −30 dB between the two input ports.

A Reconfigurable Antenna With Beam Steering and Beamwidth Variability for Wireless Communications

Abstract: A reconfigurable antenna (RA) capable of steering its beam into the hemisphere corresponding to $\theta \in $ {−40°, 0°, 40°}, $\phi \in $ {0°, 45°, 90°, −45°}, and of changing 3 dB beamwidth, where $\theta _{3\,\text {dB}} \in $ (40°, 100°), $\phi \in $ {45°, 90°, −45°} for broadside direction is presented. The RA operating in 5 GHz band consists of a driven patch antenna with a parasitic layer placed above it. The upper surface of the parasitic layer has two pixelated metallic strips, where each strip has four pixels. The pixels connected via p-i-n diode switches enable to change the current distribution on the antenna providing the desired modes of operation. A prototype RA was characterized indicating an average gain of 8 dB. Measured and simulated impedance and radiation patterns agreed well. The proposed RA offers an efficient solution by using less number of switches compared to other RAs. The system level simulations for a 5G orthogonal frequency division multiple access system show that the RA improves capacity/coverage tradeoff significantly, where the RA modes and users are jointly determined to create proper beamwidth and directivity at the access point antennas. For a hotspot scenario, the presented RA provided 29% coverage and 16% capacity gain concurrently.

Metamaterial-Based Highly Isolated MIMO Antenna for Portable Wireless Applications

Abstract: In this paper, a metamaterial structure is presented to lower the mutual coupling between the closely spaced microstrip patch antenna elements. Two elements Multiple Input Multiple Output (MIMO) antenna is closely placed with each other at edge to edge separation of 0.135 λ 0 (7 mm). Isolation improvement of 9 dB is achieved by keeping the metamaterial structure in between the MIMO elements. With the proposed structure, the isolation is achieved around −24.5 dB. Due to low ECC, high gain, low channel capacity loss and very low mutual coupling between elements, the proposed antenna is a good candidate for the MIMO applications. The proposed antenna is fabricated and tested. A reasonable agreement between simulated and measured results is observed.

Filtering Antenna With High Selectivity Using Multiple Coupling Paths From Source/Load to Resonators

Abstract: This communication presents a filtering antenna with high selectivity using multiple coupling path from source/load to resonators. The high selectivity of the filtering antenna’s boresight gain response is achieved by a novel coupling scheme, which induces additional coupling between source/load and nonadjacent resonators to construct cross coupling paths. Thanks to the extra cross-coupling paths, the filtering antenna can generate a maximum of N radiation nulls with N resonators. Besides, a resonator using a combination of open-ended stub and short-ended stub is adopted to construct this novel coupling scheme more easily. For demonstration, a three-order filtering stacked patch antenna with a center frequency of 2.3 GHz and a fractional bandwidth of 15.2% is fabricated. Two independently controllable radiation nulls are located at 1.97 and 2.61 GHz. Unidirectional radiation patterns have been achieved with cross polarization lower than −20 dB and back lobes lower than −18 dB.

Stacked Microstrip Linear Array for Millimeter-Wave 5G Baseband Communication

Abstract: A 42-element microstrip parasitic patch antenna is developed in the millimeter-wave band for fifth-generation mobile communication base stations. A metalized elliptical stripline-to-embedded-microstrip transition with adaptive via-hole arrangement as well as a 20 dB Chebyshev tapered six-way power divider is proposed to have an insertion loss of 0.045 dB. To confirm the feasibility of the antenna, it has been measured to provide a 6.3% fractional bandwidth from 26.83 to 28.56 GHz at VSWR of less than 1.96. The array antenna gains of more than 21.4 dBi have been realized with sidelobe levels of better than –19.1 dB, operating within 27.5–28.5 GHz in both the azimuth and elevation directions.

A Systematic Investigation of Rectangular Patch Antenna Bending Effects for Wearable Applications

Abstract: The emerging applications for wearable electronics have experienced enormous growth over the last decade. Antennas, being one of the critical components in modern wireless devices, thus need to be specifically designed to function while being worn and bent. In this paper, we present a systematic investigation of the effects of bending applied on wearable patch antennas over cylindrical surfaces. The resonant frequency variations and radiation pattern variations have been studied by simulating and measuring patch antennas that are bent by different angles. A frequency shift plot with respect to bending radius has been generated to target antennas for various wearable applications. An analytical approach has been presented to study the effect of resonant frequency shifting for both E- and H-planes bending. A lumped element circuit model is used to interpret the E-plane bending from different perspectives. One of the main objectives of this paper is to develop useful design-oriented charts and provide a better understanding of the effects of antenna bending to assist wearable antenna designers.

Millimeter wave microstrip patch antenna for 5G mobile communication

Abstract: This paper presents a micro strip patch antenna for future 5G-communication technology at centered frequency 38GHz and 54GHz having bandwidth 1.94GHz and 2GHz respectively with low cost substrate and small size patch best suited for miniaturized devices. It consists of Rogers RT5880 (lossy) substrate with dielectric constant 2.2 with loss tangent of 0.0013 and standard thickness 0.508mm, PEC patch and PEC ground. Substrate of dimensions 6mm×6.25mm and patch with dimensions 2mm×2mm is used. Microstrip-line feeding technique is used. Array having 4 elements with 4mm spacing has been proposed to achieve 12 dB gain for mobile data Applications on millimeter wave frequencies at 38.6GHz, 47.7GHz and 54.3GHz having bandwidth 3.5GHz, 2.5GHz and 1.3GHz respectively with Tapered line feeding. Overall size of antenna is 6mm×6.25mm×0.578mm. The proposed Antenna design is simulated on CST Microwave Studio.

A Wideband Reconfigurable Antenna With 360° Beam Steering for 802.11ac WLAN Applications

Abstract: A novel 360° beam steering patch antenna with parasitic elements is presented in this paper. The designed antenna consists of a radiating patch and six parasitic elements, each of which is connected through a group of shorting vias controlled by p-i-n diode switches. By switching on the desired groups of the shorting vias, the electric field distribution inside substrate cavity appears at the desired beam direction. Rotationally switching on the groups of the shorting vias, the performance of 360° beam scanning is realized. To further understand operating mechanism, the antenna is modeled with equivalent circuit in terms of the on and off status of a sector of the antenna, which can be used as a design guide for shorting-vias-controlled reconfigurable microstrip patch antennas. The fabricated antenna achieves a bandwidth of 14.5%, a peak gain of 10 dBi, and the efficiency of 80.5%. The achieved beamwidths are 42° and 97° in azimuth and elevation planes, respectively. With an ability of being steered around zenith axis at six directions, the scanned beam range covers the entire 360°. The physical dimension is only $2.5\lambda _{g}$ for the size and $0.5\lambda _{g}$ for the profile. This antenna operates from 5.1 to 5.9 GHz and has significant meaning in the IEEE 802.11ac wireless local area network applications due to its capabilities of generating 360° steered beams.

High Gain and Wideband High Dense Dielectric Patch Antenna Using FSS Superstrate for Millimeter-Wave Applications

Abstract: Gain and bandwidth enhancement of low profile, linearly polarized square dense dielectric patch antennas using a frequency selective surface (FSS) superstrate layer is proposed. A high dense dielectric patch antenna is utilized as a radiating element instead of a metallic patch in order to gain several significant advantages, including low profile, wide bandwidth, and high radiation efficiency. The implemented antenna is excited by an aperture-coupled feeding technique. The antenna gain is enhanced by using a highly reflective FSS superstrate layer, realizing an antenna gain enhancement of 11 dBi. The implemented antenna acquired a measured gain of about 17.78 dBi at 28 GHz with a 9% bandwidth and radiation efficiency of 90%. The bandwidth of the proposed antenna is improved by using a unit cell printed on two sides, as it provides a positive phase gradient over the desired frequency range. The antenna impedance bandwidth is broadened and the measured impedance matching $S{11}$ exhibited a 15.54% instead of 9% bandwidth while maintaining a high-gain characteristic of about 15.4 dBi. The implemented antenna presents a solid radiation performance with good agreement between the measured and simulation results. For some attractive advantages such as low profile, low cost, lightweight, small size, and ease of implementation, the proposed antenna is a very good candidate for millimeter-wave wireless communications.

Sidelobe-Reduced and Gain-Enhanced Square Patch Antennas With Adjustable Beamwidth Under TM 03 Mode Operation

Abstract: A square patch antenna operating under TM03 mode is proposed in this paper to realize gain enhancement, sidelobe reduction, and adjustable beamwidth by reshaping the surface current distribution on the patch resonator. On the one hand, by introducing transverse slots along the central line of patch, the medial part of out-of-phase longitudinal current is interrupted to circulate with little radiation. In this way, the patch serves as a full-wave dipole rather than a $3\lambda $ /2 one, and thus, the sidelobe level (SLL) in the E-plane is substantially reduced. On the other hand, the slots are installed in proximity to the nonradiative edges and at the patch center, respectively, to arouse distinctive effect on the current densities across the width of patch. Consequently, the beamwidth in the H-plane can be freely adjusted by different configurations of these slots. At last, a square patch antenna with three cascaded slots loaded along the central line is designed, fabricated, and tested. The simulated and measured results show that the directivity of a single proposed patch antenna can achieve as high as 13.3 dB with the SLL reduced to about −20 dB.

A Radiating Near-Field Patch Rectenna for Wireless Power Transfer to Medical Implants at 2.4 GHz

Abstract: A radiating near-field method of recharging and activating medical implants using a 2.4-GHz rectifying patch antenna (rectenna) is designed and tested. Traditional near-field charging uses magnetically coupled coils, but these are highly sensitive to misalignments between the transmitter and receiver. In contrast, the proposed design employs the principles of wireless power transfer using radiating antennas. These antennas provide a misalignment-insensitive power delivery method, even when the receive antenna footprint is small (27.5 mm × 19.75 mm). A misalignment analysis is performed up to 15 cm, showing a maximum loss of 7.5 dB. As a proof-of-concept demonstration, a rectenna receiver was fabricated consisting of a patch antenna attached to a radio frequency (RF) rectifier. This integrated rectifier is a voltage quadrupling circuit that provides RF–DC rectification with efficiency of 40% at 0 dBm. For validation, a real-time actuation of a medical drug pump is demonstrated using only wirelessly transmitted power with no additional power storage elements.

Dual Circular-Polarized SIW-Fed High-Gain Scalable Antenna Array for 60 GHz Applications

Abstract: In this paper, a dual circularly polarized high-gain scalable antenna array is proposed for the 60 GHz applications. The array consists of cross-slot-coupled cavity-backed square patch antenna elements fed by a novel substrate-integrated waveguide network. In our design, the two polarizations share the common radiating element and feed network so that they exhibit similar performance in terms of bandwidth, gain, and radiation patterns for both polarizations. An $8 \times 8$ element array is designed to demonstrate its function, and the simulated data exhibit an overlapped bandwidth (SWR < 2, 3 dB down gain bandwidth and AR < 3 dB) of approximately 23%, a gain up to 25.8 dBic for both ports, and a port-to-Port isolation larger than 14 dB. Good unidirectional and symmetrical radiation patterns are observed. A prototype is fabricated, and the measured results agree with the simulated ones with acceptable disparities. The reported structure is built by the conventional printed circuit board technology which is cost effective. With these advantages, the proposed scalable antenna design is a good candidate for millimeter-wave wireless communications.

Dual-Beam Filtering Patch Antennas for Wireless Communication Application

Abstract: A dual-beam filtering patch antenna consisting of a slotted patch, a metal strip underneath the patch, two pins, and a ground plane is proposed for wireless communication application. A wide operation band with stable symmetrical dual-beam far-field radiation pattern is obtained, and two radiation nulls at the lower and the upper band edges, respectively, are controlled to ensure a sharp rolloff rate at the band edges for both reflection coefficient and realize gain. Undesired higher modes can be suppressed over the stopband by changing the spacing between the patch and ground pane With entire height of $0.058~\lambda _{0}$ , the proposed antenna is implemented to show a −10 dB bandwidth of 3.0–3.8 GHz, a consistent realized gain of about 6.8 dBi within the passband for both two radiation beams directed at ±30°, out-of-band radiation suppression level of higher than 17 dBi, and good band-edge selectivity.

Circularly Polarized Antenna With Reconfigurable Broadside and Conical Beams Facilitated by a Mode Switchable Feed Network

Abstract: A pattern-reconfigurable slot-augmented patch antenna is reported that radiates circularly polarized (CP) fields and is switchable between a broadside and a conical radiating mode. Two novel design strategies were adopted to realize these advantageous performance characteristics. First, a mode switchable feed network which includes a set of eight L-probes was developed that facilitates the proper excitation of either the patch’s TM11 or TM21 mode and yields symmetric radiation patterns. Second, their operating bands were made to overlap by augmenting this patch with an annular slot. Consequently, the radiation pattern is easily switched between the broadside and the conical modes within the overlapping operational bandwidths. A prototype was fabricated and tested. The measured results are in good agreement with their simulated values, verifying the design concepts. The measured operating bandwidth, 7.8% from 2.45 to 2.65 GHz, was determined from the overlap of the impedance and axial ratio bandwidths for both modes. The measured realized gain values are stable for both radiating states within this operational bandwidth, the broadside (conical) peak value being 8.5 dBic (5.8 dBic). The CP pattern reconfigurability of this antenna with its favorable performance characteristics makes it an ideal candidate for many RFID and satellite communication applications.

Asymmetric CPW-fed SRR patch antenna for WLAN/WiMAX applications

Abstract: In this paper, a compact asymmetric coplanar waveguide (CPW) feed with split-ring resonator (SRR) is proposed to resonate at dual-band operations for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The asymmetric CPW-fed SRR patch (ACSP) antenna consists of a meander line, square-shaped split ring, and CPW ground plane. The proposed ACSP antenna resonates at two operating frequencies, namely, 2.48 GHz (2.4–2.74 GHz) and 3.49 GHz (3.25–3.64 GHz) with reflection coefficients (S11) of −16.65 dB and −32.67 dB, respectively. The measured results agree closely with the simulation results of the proposed antenna.

A Conformal Differentially Fed Antenna for Ingestible Capsule System

Abstract: A conformal differentially fed antenna at 915 MHz industrial, scientific, and medical (902–928 MHz) band for monitoring in body core temperature is presented in this paper. In virtue of its characteristics of ultrathin and flexible substrate, the peculiarity that proposed antenna can be wrapped around the capsule inner wall demonstrates the satisfactory performance of occupying a little space. The volume of the conformal patch antenna only measures 30 mm3 by notching meandering slots to achieve miniaturization. The simulated impedance bandwidth ( $\vert S_{11}\vert dB) covers from 861 to 942 MHz. The integrated capsule system, inserted in a cubic homogeneous muscle phantom for initial parametric studies and optimization, occupies the dimensions of 22 mm (length) $\times11$ mm (diameter). Meanwhile, the performance on the sensitivity to surrounding environment and specific absorption rate distribution are studied. In the measurements, the conformal antenna is rolled around a 3-D-printed capsule inside minced pork. The pork temperature data are monitored in time and transferred wirelessly. To confirm the system reliability, hardware circuits are designed with differential concept and a data logger is also realized to record in-time temperature data. Finally, the feasibility of system function demonstrates the suitability of the conformal differentially fed antenna in biomedical applications.

Wideband Low-Profile Highly Isolated MIMO Antenna With Artificial Magnetic Conductor

Abstract: A wideband highly isolated multiple-input–multiple-output patch antenna with an artificial magnetic conductor (AMC) ground plane is proposed in this letter. The antenna, which is rotationally symmetrical, is constructed by V-shaped patches coupled by a bowtie dipole. The bowtie dipole and the V-shaped parasitic patches produce two resonant modes that are coupled together. Therefore, a wide impedance bandwidth is obtained. Thanks to the orthogonal feeding and the rotationally symmetrical geometry, the antenna exhibits high port isolation as well as symmetrical radiation patterns with a compact size of 40 × 40 × 1.524 mm3. By placing an AMC ground plane with a distance of 10.5 mm below the radiating element, the antenna can achieve a unidirectional high gain with a lower height of the profile compared to that with perfect electrical conductor ground. Measured results show the antenna has an impedance bandwidth of 31.0% (3.0–4.1 GHz) with port isolation better than 25 dB. The peak gain can reach 7.1 dBi with stable and symmetrical radiation patterns.

Trident-shape strip loaded dual band-notched UWB MIMO antenna for portable device applications

Abstract: In this paper, a novel compact dual band-notched ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna of size 22 × 26 × 0.8 mm 3 is proposed for portable devices. The antenna comprises of two stepped slot UWB antennas fed by 50 ohms microstrip line, T-shape slot and narrow slot. Dual band-notches from 5.4 to 5.86 GHz and 7.6–8.4 GHz are achieved by loading trident-shape strips on microstrip line. A T-shape slot is used on the ground plane to enhance impedance matching characteristics and to minimize mutual coupling above 4 GHz. To improve isolation further at 3–4 GHz, a narrow slot is used on ground. The proposed antenna is giving a good bandwidth ranging from 3.1 to 11.8 GHz with |S 11 | > 10 dB and mutual coupling larger than 20 dB in the entire operating band except at two rejected bands. The simulation and measurement results demonstrate that the antenna is more suitable for portable device applications.