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Showing papers on "Dipole antenna published in 2013"


Journal ArticleDOI
TL;DR: In this paper, a planar-monopole (PM) antenna with microstrip-fed printed on one side of the substrate and placed perpendicularly to each other to achieve good isolation is proposed.
Abstract: A compact multiple-input-multiple-output (MIMO) antenna with a small size of 26×40 mm2 is proposed for portable ultrawideband (UWB) applications. The antenna consists of two planar-monopole (PM) antenna elements with microstrip-fed printed on one side of the substrate and placed perpendicularly to each other to achieve good isolation. To enhance isolation and increase impedance bandwidth, two long protruding ground stubs are added to the ground plane on the other side and a short ground strip is used to connect the ground planes of the two PMs together to form a common ground. Simulation and measurement are used to study the antenna performance in terms of reflection coefficients at the two input ports, coupling between the two input ports, radiation pattern, realized peak gain, efficiency and envelope correlation coefficient for pattern diversity. Results show that the MIMO antenna has an impedance bandwidth of larger than 3.1-10.6 GHz, low mutual coupling of less than -15 dB, and a low envelope correlation coefficient of less than 0.2 across the frequency band, making it a good candidate for portable UWB applications.

427 citations


Journal ArticleDOI
TL;DR: Experimental and numerical results show that the radiation characteristics, impedance matching, and SAR values of the proposed design are significantly improved compared to conventional monopole and dipole antennas, which makes it a good candidate for the wearable telemedicine application.
Abstract: We present a flexible, compact antenna system intended for telemedicine applications. The design is based on an M-shaped printed monopole antenna operating in the Industrial, Scientific, and Medical (ISM) 2.45 GHz band integrated with a miniaturized slotted Jerusalem Cross (JC) Artificial Magnetic Conductor (AMC) ground plane. The AMC ground plane is utilized to isolate the user's body from undesired electromagnetic radiation in addition to minimizing the antenna's impedance mismatch caused by the proximity to human tissues. Specific Absorption Rate (SAR) is analyzed using a numerical human body model (HUGO) to assess the feasibility of the proposed design. The antenna expresses 18% impedance bandwidth; moreover, the inclusion of the AMC ground plane increases the front to back ratio by 8 dB, provides 3.7 dB increase in gain, in addition to 64% reduction in SAR. Experimental and numerical results show that the radiation characteristics, impedance matching, and SAR values of the proposed design are significantly improved compared to conventional monopole and dipole antennas. Furthermore, it offers a compact and flexible solution which makes it a good candidate for the wearable telemedicine application.

349 citations


Journal ArticleDOI
TL;DR: In this article, a tightly coupled dipole array with an integrated balun (TCDA-IB) is developed which achieves 7.35:1 bandwidth (0.68 - 5.0 GHz) while scanning to ±45° in all directions, subject to.
Abstract: A key challenge in the design of wideband dipole phased arrays is the design of equally wideband baluns which are sufficiently compact to fit within the unit cell (typically in the linear dimension at low frequencies). In this paper, we exploit the reactance of a compact Marchand balun as an impedance matching network for each array element. The elimination of bulky external baluns results in a significant reduction of size, weight and cost, while the bandwidth is simultaneously improved by over 30%, compared to standard feeding techniques. In this manner, a tightly coupled dipole array with an integrated balun (TCDA-IB) is developed which achieves 7.35:1 bandwidth (0.68 - 5.0 GHz) while scanning to ±45° in all directions, subject to . In a dual-polarization configuration, the TCDA-IB has low cross polarization of over the majority of the band. Measured results are presented for a prototype 8 × 8 element TCDA-IB, showing good agreement with simulation.

304 citations


Journal ArticleDOI
TL;DR: In this paper, a new microstrip monopolar patch antenna is proposed and analyzed using a cavity model, which is constructed on a circular patch antenna that is shorted concentrically with a set of conductive vias.
Abstract: A new microstrip monopolar patch antenna is proposed and analyzed. The antenna has a wide bandwidth and a monopole like radiation pattern. Such antenna is constructed on a circular patch antenna that is shorted concentrically with a set of conductive vias. The antenna is analyzed using a cavity model. The cavity model analysis not only distinguishes each resonating mode and gives a physical insight into each mode of the antenna, but also provides a guideline to design a broadband monopolar patch antenna that utilizes two modes (TM01 and TM02 modes). Both modes provide a monopole like radiation pattern. The proposed antenna has a simple structure with a low profile of 0.024 wavelengths, and yields a wide impedance bandwidth of 18% and a maximum gain of 6 dBi.

282 citations


Journal ArticleDOI
TL;DR: This paper exploits the potential of large antenna arrays at millimeter-wave (mm-Wave) frequencies to develop a low-complexity directional modulation technique, Antenna Subset Modulation (ASM), for point-to-point secure wireless communication.
Abstract: The small carrier wavelength at millimeter-wave (mm-Wave) frequencies enables featuring a large number of co-located antennas. This paper exploits the potential of large antenna arrays to develop a low-complexity directional modulation technique, Antenna Subset Modulation (ASM), for point-to-point secure wireless communication. The main idea in ASM is to modulate the radiation pattern at the symbol rate by driving only a subset of antennas in the array. This results in a directional radiation pattern that projects a sharply defined constellation in the desired direction and expanded further randomized constellation in other directions. Two techniques for implementing ASM are proposed. The first technique selects an antenna subset randomly for every symbol. While randomly switching antenna subsets does not affect the symbol modulation for a desired receiver along the main direction, it effectively randomizes the amplitude and phase of the received symbol for an eavesdropper along a sidelobe. Using a simplified statistical model, an expression for the average uncoded symbol error rate (SER) is derived as a function of the observation angle. To overcome the problem of large sidelobes in random antenna subset switching, the second technique uses an optimized antenna subset selection procedure based on simulated annealing to achieve superior performance compared with random selection. Numerical comparisons of the SER performance and secrecy capacity of the proposed techniques against those of conventional array transmission are presented to highlight the potential of ASM.

245 citations


Journal ArticleDOI
TL;DR: In this paper, a dual band-notched ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with high isolation was designed on a FR4 substrate.
Abstract: A compact dual band-notched ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with high isolation is designed on a FR4 substrate (27 × 30 × 0.8 mm3). To improve the input impedance matching and increase the isolation for the frequencies ≥ 4.0 GHz, the two antenna elements with compact size of 5.5 × 11 mm2 are connected to the two protruded ground parts, respectively. A 1/3 λ rectangular metal strip producing a 1.0 λ loop path with the corresponding antenna element is used to obtain the notched frequency from 5.15 to 5.85 GHz. For the rejected band of 3.30-3.70 GHz, a 1/4 λ open slot is etched into the radiator. Moreover, the two protruded ground parts are connected by a compact metal strip to reduce the mutual coupling for the band of 3.0-4.0 GHz. The simulated and measured results show a bandwidth with |S11| ≤ -10 dB, |S21| ≤ -20 dB and frequency ranged from 3.0 to 11.0 GHz excluding the two rejected bands, is achieved, and all the measured and calculated results show the proposed UWB MIMO antenna is a good candidate for UWB MIMO systems.

237 citations


Journal ArticleDOI
TL;DR: In this paper, a differentially-driven dual-polarized magneto-electric dipole antenna was proposed to achieve wide impedance and gain bandwidth with high differential port-to-port isolation.
Abstract: A novel differentially-driven dual-polarized antenna is proposed in this communication. It is a magneto-electric dipole antenna whose gain and beamwidth keep constant along frequency within the operation bandwidth. If the antenna is ideally symmetrical, its differential port-to-port isolation is theoretically infinite. Due to the differentially-driven scheme, its cross-polarization level can be very low. Measurement shows that the proposed antenna achieves a wide impedance bandwidth of 68% (0.95 to 1.92 GHz) for differential reflection coefficients less than -10 dB and high differential port-to-port isolation of better than 36 dB within the bandwidth. The 3-dB-gain bandwidth of the proposed antenna is 62% (1.09 to 2.08 GHz), and the radiation pattern across it is stable and unidirectional. The broadside gain within the 3-dB-gain bandwidth ranges from 6.6 to 9.6 dBi. The cross-polarization level is lower than -23 dB across the 3-dB-gain bandwidth. The proposed antenna is the first differentially-driven dual-polarized magneto-electric dipole antenna. A feeding structure is specially designed to fit the differentially-driven scheme, and also to achieve wide impedance and gain bandwidths.

219 citations


Journal ArticleDOI
TL;DR: In this article, a coplanar waveguide-fed compact ultrawideband (UWB) microstrip antenna is proposed for UWB applications, where the ground was vertically extended toward two sides of the single radiator.
Abstract: A novel coplanar waveguide (CPW)-fed compact ultrawideband (UWB) microstrip antenna is proposed for ultrawideband applications. The proposed antenna posseses a method to minimize the monopole antenna by loading of inverted L-strip over the conventional monopole patch antenna to lower the height of the antenna. The ground was vertically extended toward two sides of the single radiator. Therefore, the large space around the radiator that is usually wasted can be effectively saved. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with overall size of $25 \times 25 \times 1.6\ {\hbox{mm}}^3$ achieves good impedance matching, constant gain, stable radiation patterns, and constant group delay over an operating bandwidth of 2.6-13.04 GHz (10.44 GHz).

216 citations


Journal ArticleDOI
TL;DR: In this article, a dual-band rectenna operating at 915 MHz and 2.45 GHz was proposed, which is optimized for low input power densities using harmonic balance (HB) simulation.
Abstract: A compact dual-band rectenna operating at 915 MHz and 2.45 GHz is presented. The rectenna consists of a slot-loaded dual-band folded dipole antenna and a dual-band rectifier. The length of the proposed antenna is only 36.6% of the half-wavelength $(\lambda_{0}/2)$ dipole antenna at 915 MHz while keeping dual-band property at 915 MHz and 2.45 GHz. The rectifier circuit is optimized for low input power densities using harmonic balance (HB) simulation. The efficiencies of the rectifier are evaluated with both single- and dual-frequency input signals. The measured results show an efficiency of 37% and 30% at 915 MHz and at 2.45 GHz when illuminated by a microwave signal of available power of $-$ 9 dBm for a load resistor of 2.2 k $\Omega$ .

207 citations


Patent
Gabriel Isaac Mayo1
02 Dec 2013
TL;DR: In this article, a first antenna array of antenna coils is configured to generate a first wireless field and a second antenna array generates a second wireless field, at least partially overlaps the first and second antenna arrays.
Abstract: Systems and methods for wireless power transmission are described herein In one aspect, an apparatus for wireless power transmission comprises a first antenna array of antenna coils configured to generate a first wireless field A second antenna array of antenna coils generates a second wireless field The first antenna array at least partially overlaps the second antenna array A driver circuit generates first and second drive signals for generation of the first and second wireless fields via the first and second antenna arrays, respectively The first wireless field is orthogonal with respect to the second wireless field The first antenna array and the driver circuit power the antenna coils of the first antenna array with alternating polarities The second antenna array and the driver circuit power the antenna coils of the second antenna array with alternating polarities

206 citations


Patent
21 Oct 2013
TL;DR: In this article, a surface scattering antenna with an electromagnetic waveguide structure and a plurality of electromagnetic wave scattering elements is described, and a gain definition circuit defines a radiation pattern configured to acquire a possible interfering signal.
Abstract: Described embodiments include an antenna system and method. The antenna system includes a surface scattering antenna that has an electromagnetic waveguide structure and a plurality of electromagnetic wave scattering elements. The plurality of electromagnetic wave scattering elements are distributed along the waveguide structure, have a respective activatable electromagnetic response to a guided propagating electromagnetic wave, and produce a controllable radiation pattern. A gain definition circuit defines a radiation pattern configured to acquire a possible interfering signal. The defined antenna radiation pattern has a field of view covering at least a portion of an undesired field of view of an associated antenna. An antenna controller establishes the defined radiation pattern in the surface scattering antenna by activating the respective electromagnetic response of selected electromagnetic wave scattering elements. A correction circuit reduces an influence of the received possible interfering signal in a contemporaneously received signal by the associated antenna.

Patent
18 Dec 2013
TL;DR: In this paper, a three-dimensional transmitting antenna for wireless power charging, which wirelessly transmits power to charge a device, includes a first antenna coil section for producing a magnetic field in a first direction, and a second antenna coils section for generating a magnetic fields in a second direction.
Abstract: The present invention has been made in an effort to overcome the disadvantage that a user has to consciously adjust the positions of a wireless power transmitter and a wireless power receiver. The transmitting antenna for wireless power charging, which wirelessly transmits power to charge a device, includes a first antenna coil section for producing a magnetic field in a first direction, and a second antenna coil section for producing a magnetic field in a second direction. Accordingly, the three-dimensional transmitting antenna can minimize decreases in efficiency caused by the position and direction of the receiver and maximize reception efficiency at a particular point or within a particular range.

Journal ArticleDOI
TL;DR: In this article, a new microstrip Yagi array antenna with end-fire radiation and vertical polarization is proposed, which has a low profile, a wide bandwidth and a high gain.
Abstract: A new microstrip Yagi array antenna with endfire radiation and vertical polarization is proposed. The Yagi antenna has a low profile, a wide bandwidth and a high gain. Each element of the Yagi array is based on a new microstrip antenna that has one edge opened and the other three edges shorted, working as a “magnetic dipole antenna”. As opposed to previous microstrip Yagi array antennas, the proposed Yagi antenna could produce a beam radiating at exactly endfire for infinite ground plane, with vertical polarization in the horizontal plane. A coupling microstrip line is introduced between the driven element and the first director element to strengthen the coupling between them, and therefore the front-to-back ratio and bandwidth of the array can be improved. The endfire gain can be enhanced as the number of the director elements increases, in either case where the array has an infinite or a finite ground plane.

Journal ArticleDOI
TL;DR: Convex optimization is used to determine current distributions that provide upper bounds on the antenna performance and formulations for maximal gain Q-Factor quotient, minimal Q-factor for superdirectivity, and minimum Q for given far-fields are presented.
Abstract: The high Q-factor (low bandwidth) and low efficiency make the design of small antennas challenging. Here, convex optimization is used to determine current distributions that provide upper bounds on the antenna performance. Optimization formulations for maximal gain Q-factor quotient, minimal Q-factor for superdirectivity, and minimum Q for given far-fields are presented. The effects of antennas embedded in structures are also discussed. The results are illustrated for planar geometries.

Patent
28 Mar 2013
TL;DR: In this paper, the antenna switching circuitry is adapted to selectively couple one or more of a plurality of transmit and receive ports to the first antenna port and the second antenna port, respectively.
Abstract: Radio frequency front end circuitry comprises a first antenna port, a second antenna port, antenna switching circuitry, a first diplexer, and a second diplexer. The antenna switching circuitry is coupled to each of the first antenna port and the second antenna port through the first diplexer and the second diplexer, respectively. The antenna switching circuitry is adapted to selectively couple one or more of a plurality of transmit and receive ports to the first antenna port and the second antenna port.

Patent
06 Mar 2013
TL;DR: An antenna element having a vertically stacked structure and a phased array antenna that includes a plurality of antenna elements sharing a common conductive ground plane are described in this article. But the authors do not specify a beam steering system that can be configured for steering an energy beam produced by the antenna elements.
Abstract: An antenna element having a vertically stacked structure and a phased array antenna that includes a plurality of antenna elements sharing a common conductive ground plane are described. The phased array antenna also includes a common conductive shell electrically coupled to the common conductive ground plane and extending away there from to encompass the antenna elements. The common conductive shell and the common conductive ground plane together define a common cavity having a common aperture. The phased array antenna also includes a common dielectric superstrate layer disposed over the common cavity at a predetermined distance from the antenna elements and a beam steering system coupled to the antenna elements and configured for steering an energy beam produced by the phased array antenna.

Patent
21 Oct 2013
TL;DR: In this article, the antenna system includes at least two surface scattering antenna segments, each segment includes a respective electromagnetic waveguide structure, and a respective plurality of electromagnetic wave scattering elements.
Abstract: Described embodiments include an antenna system and method. The antenna system includes at least two surface scattering antenna segments. Each segment includes a respective electromagnetic waveguide structure, and a respective plurality of electromagnetic wave scattering elements. The wave scattering elements are distributed along the waveguide structure, have an inter-element spacing substantially less than a free-space wavelength of a highest operating frequency of the antenna segment, have a respective activatable electromagnetic response to a propagating guided wave, and are operable in combination to produce a controllable radiation pattern. A gain definition circuit defines a series of at least two radiation patterns selected to facilitate a convergence on an antenna radiation pattern that maximizes a radiation performance metric. An antenna controller sequentially establishes each radiation pattern. A receiver receives the desired field of view signal and the undesired field of view signal.

Journal ArticleDOI
TL;DR: In this article, a L-probe patch antenna array using multilayer low temperature co-fired ceramic (LTCC) technology is presented for 60 GHz band applications. The proposed antenna array is designed with a high gain in the impedance bandwidth by introducing a novel soft-surface structure.
Abstract: A 4 $\,\times\,$ 4 L-probe patch antenna array using multilayer low temperature co-fired ceramic (LTCC) technology is presented for 60-GHz band applications. The proposed antenna array is designed with a high gain in the impedance bandwidth by introducing a novel soft-surface structure. The soft-surface structure comprised of metal strips and via fences reduces the losses caused by severe surface waves and mutual coupling between adjacent elements to improve the radiation performance. The proposed antenna array is convenient for integrated applications. The fabricated antenna array excluding the measurement transition has dimension of 14.4 $\,\times\,$ 14.4 $\,\times\,$ 1 mm $^{3}$ . The simulated and measured impedance and radiation performance are studied and compared. Good agreement is achieved between simulation and measurement. The proposed antenna array shows a wide simulated impedance of 29% from 53 GHz to 71 GHz for $\vert {S}_{11}\vert dB, measured broadband 3-dB gain bandwidth of 18.3% from 54.5 GHz to 65.5 GHz and the gain up to 17.5 dBi at 60 GHz, respectively.

Patent
05 Nov 2013
TL;DR: In this paper, an RFID reader is provided that includes an antenna array comprising multiple antenna elements circumferentially distributed around a longitudinal axis of the antenna array, each antenna element includes multiple patch elements disposed above one or more underlying substrates.
Abstract: An RFID reader is provided that includes an antenna array comprising multiple antenna elements circumferentially distributed around a longitudinal axis of the antenna array. Each antenna element includes multiple patch elements disposed above one or more underlying substrates, wherein the patch elements of each antenna element are disposed on an outer side of the antenna element. Further, one or more of the antenna elements is an asymmetric antenna element, wherein a first end of the asymmetric antenna element is wider than a second, opposite end of the asymmetric antenna element, wherein a first patch element disposed proximate to the first end of the asymmetric antenna element is larger than a second patch element disposed proximate to the second end of the asymmetric antenna element, and wherein a resonant frequency associated with the first patch element is approximately the same as a resonant frequency associated with the second patch element.

Patent
13 May 2013
TL;DR: In this paper, a channel codebook is generated by identifying a subset of antenna configurations from a plurality of antennas configurations of an antenna associated with a transmitter by transmitting a sequence of symbols from the transmitter to a receiver using the plurality of antenna configuration, wherein each antenna configuration provides a unique transmission characteristic to the receiver.
Abstract: Generating a channel codebook by identifying a subset of antenna configurations from a plurality of antenna configurations of an antenna associated with a transmitter by: transmitting a sequence of symbols from the transmitter to a receiver using the plurality of antenna configurations, wherein each antenna configuration provides a unique transmission characteristic to the receiver; receiving feedback from the receiver that identifies the subset of antenna configurations; and, generating channel codebook entries corresponding to the subset of antenna configurations; and, transmitting data from the transmitter to the receiver using the channel codebook.

Patent
19 Feb 2013
TL;DR: In this paper, a V-shaped and Yagi antenna array for vehicular direction finding applications is presented, which is a circular disc having a plurality of microstrip antennas radially spaced around the disc at equal angles.
Abstract: The circular antenna array for vehicular direction finding applications is a circular disc having a plurality of microstrip antennas radially spaced around the disc at equal angles. In one embodiment, the circular antenna array includes V-shaped antennas, and in another embodiment, the antennas are Yagi antennas. The circular antenna array can operate under two modes, switched and phased, in the 2.45 GHz band with an operating bandwidth of at least 100 MHz. The circular antenna array is configured to be installed in vehicles. Selective transmittal of an RF signal from a key fob generates a response signal from a specific antenna element receiving the RF signal in line with the direction of origin thereof. An LED panel indicates proximity and direction to the vehicle being located.

Journal ArticleDOI
TL;DR: In this article, a 60 GHz wideband circularly polarized (CP) U-slot patch antenna array of 4 × 4 elements on low temperature co-fired ceramic (LTCC) is presented.
Abstract: This communication presents a 60-GHz wideband circularly polarized (CP) U-slot patch antenna array of 4 × 4 elements on low temperature cofired ceramic (LTCC). A CP U-slot patch antenna is used as the array element to enhance the impedance bandwidth and a stripline sequential rotation feeding scheme is applied to achieve wide axial ratio (AR) bandwidth. Meanwhile, a grounded coplanar waveguide (GCPW) to stripline transition is designed for probe station measurement. The fabricated antenna array has a dimension of 14 ×16 × 1.1 mm3 . The simulated and measured impedance bandwidths, AR bandwidths, and radiation patterns are investigated and compared. Measured results show that the proposed antenna array has a wide impedance bandwidth from 50.5 GHz to 67 GHz for |S11| <; -10 dB, and a wide AR bandwidth from 54 GHz to 65.5 GHz for AR <; 3 dB. In addition, it exhibits a peak gain of 16 dBi and a beam-shaped pattern with 3-dB beam width of 20°. Moreover, its AR keeps below 3 dB within the 3-dB beam width.

Journal ArticleDOI
TL;DR: In this article, an electrically small multiband monopole antenna based on complementary split-ring resonators, which are used to reduce antenna size, is presented. But the antenna is fed by a three-stage microstrip line and provides 13, 17 and 16% impedance bandwidth performance covering the 3.5 GHz WiMAX and 2.4/5.2 GHz WLAN bands.
Abstract: Presented is an electrically small multiband monopole antenna based on complementary split-ring resonators, which are used to reduce antenna size. The antenna is fed by a three-stage microstrip line and provides 13, 17 and 16% impedance bandwidth performance covering the 3.5 GHz WiMAX and 2.4/5.2 GHz WLAN bands. Also, the proposed antenna exhibits almost an omnidirectional radiation pattern in the H-plane and a dipole-like radiation pattern in the E-plane. The return loss and radiation pattern measurements of the fabricated antenna are in very good agreement with simulation results.

Journal ArticleDOI
TL;DR: In this paper, a compact asymmetric-cross slotted square patch antenna is proposed for circularly polarized (CP) radiation with a small antenna volume of 0.292λo × 0.0308λo on a low cost FR4 substrate.
Abstract: Compact, asymmetric\symmetric-slotted\slit-microstrip patch antennas on reactive impedance surface (RIS) are proposed and studied for circularly polarized (CP) radiation. The antennas consist of a slotted-slit-microstrip patch on a RIS substrate. The CP radiation with compact size is achieved by asymmetric\symmetric-slot-slit cut along the orthogonal\diagonal directions of the patch radiator. The asymmetric\symmetric-slotted\slit microstrip patches on the RIS structure are used for further miniaturization of the antenna with improvement in CP radiation. The measured results of the compact asymmetric-cross slotted square patch antenna are 1.6% (2.51-2.55 GHz) for 3-dB axial ratio bandwidth, 5.2% (2.47-2.60 GHz) for 10-dB return loss bandwidth, and 3.41 dBic for gain over 3-dB axial ratio bandwidth. The overall antenna volume is 0.292λo × 0.292λo × 0.0308λo on a low cost FR4 substrate at 2.5 GHz.

Journal ArticleDOI
TL;DR: In this article, a non-symmetric tightly coupled dipole element for wideband phased arrays is proposed to control capacitance and cancel the ground plane inductance, where each arm on the dipole is different than the other, forming a ball-and-cup.
Abstract: It is traditionally known that wideband apertures lose bandwidth when placed over a ground plane. To overcome this issue, this paper introduces a new non-symmetric tightly coupled dipole element for wideband phased arrays. The proposed array antenna incorporates additional degrees of freedom to control capacitance and cancel the ground plane inductance. Specifically, each arm on the dipole is different than the other (or non-symmetric). The arms are identical near the center feed section but dissimilar towards the ends, forming a ball-and-cup. It is demonstrated that the non-symmetric qualities achieve wideband performance. Concurrently, a design example for planar installation with balun and matching network is presented to cover X-band. The balun avoids extraneous radiation, maintains the array's low-profile height and is printed on top of the ground plane connecting to the array aperture with 180° out of phase vertical twin-wire transmission lines. To demonstrate the concept, a 64-element array with integrated feed and matching network is designed, fabricated and verified experimentally. The array aperture is placed λ/7 (at 8 GHz) above the ground plane and shown to maintain a active VSWR less than 2 from 8-12.5 GHz while scanning up to 70° and 60° in E- and H-plane, respectively. The array's simulated diagonal plane cross-polarization is approximately 10 dB below the co-polarized component during 60° diagonal scan and follows the theoretical limit for an infinite current sheet.

Journal ArticleDOI
TL;DR: In this article, a passive wireless antenna sensor designed for strain and crack sensing was investigated, where a radio frequency identification (RFID) chip was adopted for antenna signal modulation, so that a wireless reader can easily distinguish the backscattered sensor signal from unwanted environmental reflections.
Abstract: This research investigates a passive wireless antenna sensor designed for strain and crack sensing. When the antenna experiences deformation, the antenna shape changes, causing a shift in the electromagnetic resonance frequency of the antenna. A radio frequency identification (RFID) chip is adopted for antenna signal modulation, so that a wireless reader can easily distinguish the backscattered sensor signal from unwanted environmental reflections. The RFID chip captures its operating power from an interrogation electromagnetic wave emitted by the reader, which allows the antenna sensor to be passive (battery-free). This paper first reports the latest simulation results on radiation patterns, surface current density, and electromagnetic field distribution. The simulation results are followed with experimental results on the strain and crack sensing performance of the antenna sensor. Tensile tests show that the wireless antenna sensor can detect small strain changes lower than 20???, and can perform well at large strains higher than 10?000???. With a high-gain reader antenna, the wireless interrogation distance can be increased up to 2.1?m. Furthermore, an array of antenna sensors is capable of measuring the strain distribution in close proximity. During emulated crack and fatigue crack tests, the antenna sensor is able to detect the growth of a small crack.

Patent
20 Dec 2013
TL;DR: An antenna system includes a plurality of antenna assemblies, each assembly is arranged in a different geometrical plane, the antenna assemblies include a driven component and a director array to increase the gain of the antenna assembly as discussed by the authors.
Abstract: An antenna system includes a plurality of antenna assemblies. The antenna assemblies include a driven component and a director array to increase the gain of the antenna assembly. For each antenna assembly of the plurality of antenna assemblies, the driven component and director array are disposed in an antenna plane. Each antenna assembly is arranged in a different geometrical plane.

Journal ArticleDOI
TL;DR: In this paper, a multi-band, circularly polarized (CP), wide beamwidth, and highly efficient antenna for use in global positioning systems (GPS) is presented.
Abstract: This communication presents a multi-band, circularly polarized (CP), wide beamwidth, highly efficient antenna for use in global positioning systems (GPS). The primary radiating elements are two crossed printed dipoles, which incorporate a 90° phase delay line realized with a vacant-quarter printed ring to produce the CP radiation and broadband impedance matching. To achieve multiple resonances, each dipole arm is divided into four branches with different lengths, and a printed inductor with a barbed end is inserted in each branch to reduce the radiator size. An inverted, pyramidal, cavity-backed reflector is incorporated with the crossed dipoles to produce a unidirectional radiation pattern with a wide 3-dB axial ratio (AR) beamwidth and a high front-to-back ratio. The multi-band antennas have broad impedance matching and 3-dB AR bandwidths, which cover the GPS L1-L5 bands.

Journal ArticleDOI
TL;DR: In this paper, a dual-broadband planar antenna for 2G/3G/LTE (4G) mobile communications is proposed, which consists of one element for the lower band and two elements for the upper band.
Abstract: A novel dual-broadband planar antenna is proposed for 2G/3G/LTE (4G) mobile communications. The proposed dual-broadband antenna consists of one element for the lower band and two elements for the upper band, making it possible to be arrayed without appearance of grating lobes in the upper band. The lower-band element comprises a pair of printed dipoles with a pair of parasitic elements for bandwidth enhancement. Two upper-band elements composed of two pairs of folded dipoles are nested inside the lower-band element, forming a compact arrayable antenna unit. The dual-broadband antenna achieves a bandwidth of 20% (800-980 MHz) for the lower band and a bandwidth of 60% (1540-2860 MHz) for the upper band. A dual-broadband antenna array that consists of 4 elements for the lower band and 8 elements for the upper band is developed for base station applications. The dual-broadband array achieves a bandwidth of 22% (780-980 MHz) for the lower band and a bandwidth of 68% (1470-3000 MHz) for the upper band, covering all the frequency bands for 2G/3G/LTE (4G) systems. Measured antenna gains for the array are ~12 dBi for the lower band and dBi for the upper band, suitable for potential applications in mobile communication base stations.

Journal ArticleDOI
TL;DR: In this article, a dual-polarized dipole antenna for base station applications is presented, which is composed of a cross dipole, a square loop, square plate, and a small-size reflector.
Abstract: A novel dual-polarized dipole antenna for base-station applications is presented in this letter. The proposed antenna is composed of a cross dipole, a square loop, a square plate, and a small-size reflector. The square loop and the square plate act as a parasitic radiator and a director, respectively. By introducing the two parts, the impedance bandwidth of the cross dipole can be significantly enhanced, and broadside radiation patterns with narrow beam can be also obtained. Experimental results show that the proposed antenna can operate from 1.71 to 2.69 GHz with low VSWRs at the two ports. High isolation ( > 22 dB) and stable antenna gain (~ 8 dB) are also achieved over the entire operating frequency band. The antenna has symmetrical radiation patterns both in vertical and horizontal planes, and the half-power beamwidth is 70°±5°. Furthermore, the size of the proposed antenna is very compact, which is only 0.513 λ0 ×0.513 λ0 ×0.388 λ0 at the center of the operating frequency band.