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Showing papers in "IEEE Antennas and Wireless Propagation Letters in 2014"


Journal ArticleDOI
TL;DR: In this article, a compact multiple-input-multiple-output (MIMO) antenna for ultrawideband (UWB) applications is presented, which consists of two open L-shaped slot (LS) antenna elements and a narrow slot on the ground plane.
Abstract: A compact multiple-input-multiple-output (MIMO) antenna is presented for ultrawideband (UWB) applications. The antenna consists of two open L-shaped slot (LS) antenna elements and a narrow slot on the ground plane. The antenna elements are placed perpendicularly to each other to obtain high isolation, and the narrow slot is added to reduce the mutual coupling of antenna elements in the low frequency band (3-4.5 GHz). The proposed MIMO antenna has a compact size of 32 ×32 mm 2 , and the antenna prototype is fabricated and measured. The measured results show that the proposed antenna design achieves 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 better than 0.02 across the frequency band, which are suitable for portable UWB applications.

280 citations


Journal ArticleDOI
TL;DR: In this article, a compact printed ultrawideband (UWB) slot antenna for MIMO/diversity applications is presented, which consists of two modified coplanar waveguides (CPWs) feeding staircase-shaped radiating elements for orthogonal radiation patterns.
Abstract: A novel compact printed ultrawideband (UWB) slot antenna for MIMO/diversity applications is presented in this letter. The antenna consists of two modified coplanar waveguides (CPWs) feeding staircase-shaped radiating elements for orthogonal radiation patterns, where a rectangle stub is placed at 45° between the CPW to ensure high isolations. By etching two split-ring resonator (SRR) slots on the radiators respectively, the band-notched property is achieved. Results show that this antenna meets a 10-dB impedance bandwidth and 15 dB isolation from 2.5 to 12 GHz, with a notched band at 5.5 GHz. The measurements of the radiation patterns and envelope correlation coefficient (ECC) denote that the antenna is suitable for multiple-input-multiple-output (MIMO)/diversity systems. Furthermore, it has a compact size of 48 × 48 mm2, which has been significantly reduced, and it is a good candidate for portable devices.

261 citations


Journal ArticleDOI
TL;DR: In this article, a low-profile microstrip-fed compact triple band-notched ultrawideband (UWB) antenna is proposed, where two elliptic single complementary split-ring resonators (ESCSRRs) of different dimensions from the radiating patch of the antenna are etched out.
Abstract: In this letter, a novel low-profile microstrip-fed compact triple band-notched ultrawideband (UWB) antenna is proposed. Notch bands around the 3.3-3.8-GHz WiMAX and 5.15-5.85-GHz WLAN frequencies are obtained by etching out two elliptic single complementary split-ring resonators (ESCSRRs) of different dimensions from the radiating patch of the antenna. Furthermore, by placing two rectangular split-ring resonators near the feedline-patch junction of the antenna, rejection for the 7.9-8.4-GHz X-band frequencies is achieved. Design guidelines for implementing the notch-bands at the desired frequency regions are provided. The match between the simulated and experimental results suggests that the proposed antenna can be a good candidate for application in UWB communication systems.

234 citations


Journal ArticleDOI
TL;DR: In this article, a wideband circularly polarized (CP) cross-dipole antenna fabricated on a double-layered printed circuit board (PCB) substrate for 2.45 GHz ISM band wireless communications is presented.
Abstract: This letter introduces a wideband circularly polarized (CP) cross-dipole antenna fabricated on a double-layered printed circuit board (PCB) substrate for 2.45-GHz ISM band wireless communications. Unlike conventional cross-dipole antennas, the proposed cross dipole is designed with wide open ends such that both impedance and axial-ratio (AR) bandwidths are enhanced. In addition, to excite the CP radiation effectively, a curved-delay line providing an orthogonal phase difference among the cross-dipole elements is attached at the corners of the sequentially rotated elements. By choosing a proper radius of the curved-delay line, a wide input impedance of the antenna can be realized. The antenna is center-fed by a 50- Ω coaxial cable and is placed above a square reflector to obtain a directional CP radiation pattern. With the advantage of centered feed, symmetric CP radiation patterns can be achieved across the entire operating bandwidth. Simulated and measured results confirm the proposed antenna produced good CP characteristics. An impedance bandwidth (for VSWR ≤ 2) of about 50.2% (1.99-3.22 GHz) and the 3-dB AR bandwidth of about 27% (2.30-2.9 GHz) around the center frequency of 2.45 GHz were measured. The antenna has an average CP gain of 6.2 dBic across the operating bandwidth and the maximum gain of 6.8 dBic at the center frequency. The size of antenna is 0.45λ×0.45λ×0.24λ.

170 citations


Journal ArticleDOI
TL;DR: In this article, a triple-layer transmit array antenna has been designed, fabricated, and tested at X-band, achieving a full transmission phase range of 360 degrees for a transmission magnitude equal to or better than -4.2 dB.
Abstract: A triple-layer transmitarray antenna has been designed, fabricated, and tested at X-band. Using a spiral-dipole element, a full transmission phase range of 360 ° is achieved for a transmission magnitude equal to or better than -4.2 dB. The transmission phase distribution of the transmitarray elements has been optimized to reduce the effects of the lossy elements with low transmission magnitudes on the antenna gain, leading to an average element loss as low as 0.49 dB. The measured gain of the transmitarray prototype is 28.9 dB at 11.3 GHz, resulting in a 30% aperture efficiency. Antenna bandwidths of 9% for 1-dB gain and 19.4% for 3-dB gain are achieved in this design.

160 citations


Journal ArticleDOI
TL;DR: In this paper, a screen-printed interface layer was used to reduce the surface roughness of the polyester/cotton material that facilitated the printing of a continuous conducting surface.
Abstract: This letter introduces a new technique of inkjet printing antennas on textiles. A screen-printed interface layer was used to reduce the surface roughness of the polyester/cotton material that facilitated the printing of a continuous conducting surface. Conducting ink was used to create three inkjet-printed microstrip patch antennas. An efficiency of 53% was achieved for a fully flexible antenna with two layers of ink. Measurements of the antennas bent around a polystyrene cylinder indicated that a second layer of ink improved the robustness to bending.

157 citations


Journal ArticleDOI
TL;DR: In this article, a bow-tie-shaped slot antenna is proposed to induce strong loading effect in the cavity and generate two closely spaced hybrid modes that help to get a broadband response.
Abstract: A novel design technique for broadband substrate integrated waveguide cavity-backed slot antenna is demonstrated in this letter. Instead of using a conventional narrow rectangular slot, a bow-tie-shaped slot is implemented to get broader bandwidth performance. The modification of the slot shape helps to induce strong loading effect in the cavity and generates two closely spaced hybrid modes that help to get a broadband response. The slot antenna incorporates thin cavity backing (height <;0.03λ 0 ) in a single substrate and thus retains low-profile planar configuration while showing unidirectional radiation characteristics with moderate gain. A fabricated prototype is also presented that shows a bandwidth of 1.03 GHz (9.4%), a gain of 3.7 dBi over the bandwidth, 15 dB front-to-back ratio, and cross-polarization level below -18 dB.

152 citations


Journal ArticleDOI
TL;DR: This letter presents a radiation pattern verification system for low-frequency antennas in their operative conditions, e.g., on the ground, next to other elements, etc, using a properly equipped micro unmanned aerial vehicle (UAV) as a test source.
Abstract: This letter presents a radiation pattern verification system for low-frequency antennas in their operative conditions, e.g., on the ground, next to other elements, etc. It is a far-field setup using a properly equipped micro unmanned aerial vehicle (UAV) as a test source. The micro UAV can perform an autonomous flight. Its absolute position is measured with a remote topographic instrument. By data processing, the received power pattern along the UAV flying path is reconstructed. The proposed setup has been validated on two standard wire antennas at 150 and 408 MHz with an estimated accuracy of 1 dB.

150 citations


Journal ArticleDOI
TL;DR: In this paper, a new type of wideband substrate integrated waveguide (SIW) cavity-backed patch antenna and array for millimeter wave (mmW) are investigated and implemented.
Abstract: In this letter, a new type of wideband substrate integrated waveguide (SIW) cavity-backed patch antenna and array for millimeter wave (mmW) are investigated and implemented. The proposed antenna is composed of a rectangular patch with a backed SIW cavity. In order to enhance the bandwidth and radiation efficiency, the cavity is designed to resonate at its TE210 mode. Based on the proposed antenna, a 4 × 4 array is also designed. Both the proposed antenna and array are fabricated with standard printed circuit board (PCB) process, which possess the advantage of easy integration with planar circuits. The measured bandwidth (|S11| ≤ -10 dB) of the antenna element is larger than 15%, and that of the antenna array is about 8.7%. The measured peak gains are 6.5 dBi for the element and 17.8 dBi for the array, and the corresponding simulated radiation efficiencies are 83.9% and 74.9%, respectively. The proposed antenna and array are promising for millimeter-wave applications due to its merits of wide band, high efficiency, low cost, low profile, etc.

148 citations


Journal ArticleDOI
TL;DR: In this article, a circular polarizer using a multilayer frequency selective surface based on split rings bisected by a metal strip is presented, which provides the advantages of both low cross-polarization level and low sensibility with respect to the incidence angle of the ring-based topology.
Abstract: This letter presents a circular polarizer using a multilayer frequency selective surface based on split rings bisected by a metal strip. This geometry provides the advantages of both low cross-polarization level and low sensibility with respect to the incidence angle of the ring-based topology. To validate the proposed design, a four-layer prototype to operate in Ka-band has been designed, fabricated, and tested. Experimental results show that axial ratios lower than 3 dB are obtained for angles of incidence as high as 25 ° over the frequency range of 25.5-36.5 GHz.

148 citations


Journal ArticleDOI
TL;DR: In this article, the authors proposed a time-dependent frequency offset to achieve a beampattern that is time independent for a given pair of range and angle, which can increase the detectability of the target.
Abstract: In recent years, frequency diverse array radar with fixed frequency offset has been proposed and investigated. It has been shown that the beampattern of this category of radar is time-dependent as well as range-angle-dependent. In this letter, we have proposed time-dependent frequency offset to achieve a beampattern that is time-independent for a given pair of range and angle. The proposed radar system has been analyzed mathematically, and the simulation results are presented. Simulations show that the beampattern does not change with time for a particular range-angle pair, but it remains time-dependent for other values of range and angle. With the proposed radar system, the target remains illuminated constantly for the whole pulse duration, causing a high-energy reflection that can increase detectability of the target.

Journal ArticleDOI
TL;DR: In this paper, a multiple-conductor-layers transmitarray antenna using slot-type element with no dielectric substrate has been designed, fabricated, and tested for 11.3 GHz operating frequency.
Abstract: The transmitarray antenna has received considerable attention in recent years as it combines the favorable features of the lens antenna and the array techniques. The goal of this letter is to present detailed design analysis of a multiple-conductor-layers transmitarray antenna using slot-type element with no dielectric substrate. A transmitarray antenna using quad-layer cross-slot elements has been designed, fabricated, and tested for 11.3 GHz operating frequency. The measured gain of the prototype transmitarray is 23.76 dB at 11.3 GHz. It is observed that the oblique incidence and the wave polarization have strong effect on the transmission coefficient of the slot-type element. Thus, a detailed analysis of the transmitarray considering the oblique incidence angles and the feed polarization conditions is performed with good agreement between the simulation and measured results.

Journal ArticleDOI
TL;DR: In this article, a selective frequency-reconfigurable antenna is proposed for cognitive radio applications. But the antenna is composed of a radiating element in the form of an inverted U fed by a microstrip line on its upper side.
Abstract: This letter presents a selective frequency-reconfigurable antenna, suitable for cognitive radio applications. The proposed antenna is capable of switching between a wide operating band of 2.63-3.7 GHz and four different subbands, which allows using it for sensing the entire band and then adjusting its bandwidth to select the suitable sub-band and prefilter out the other ones. The antenna is composed of a radiating element in the form of an inverted U fed by a microstrip line on its upper side. In order to achieve a selective frequency reconfiguration, four horizontal slots with integrated p-i-n diode switches are incorporated in the ground plane to act as reconfigurable filter. Some of the switches are used to alter the antenna bandwidth, while the others are employed to shift the operating band by varying the electrical length of the middle slots. To present the work, both simulated and measured results are presented, and a good agreement is achieved.

Journal ArticleDOI
TL;DR: In this article, a new technique to achieve both good isolation and dual band-notched functions for ultrawideband (UWB) multiple-input-multiple-output (MIMO) antennas was developed.
Abstract: A new technique to achieve both good isolation and dual band-notched functions for ultrawideband (UWB) multiple-input–multiple-output (MIMO) antennas was developed. The proposed antenna consists of the radiation patch connected through a via with the strip placed beneath the patch. The strip not only provides another coupling path, but also serves as the impedance transformer, resulting in good isolation ( $S_{21} dB) and dual band rejection at WiMAX (3.4–3.7 GHz) and WLAN (5.15–5.35 and 5.725–5.825 GHz) over the UWB system operation (3.1–10.6 GHz). Without decoupling element or resonator, which is often placed between the antennas to acquire good isolation or band rejection, the proposed UWB MIMO antenna requires an individual antenna element size of only 11.2 $\,\times\,$ 12 mm $^{2}\ (0.12 \lambda_{0}\times 0.11 \lambda_{0})$ and overall MIMO antenna size of 30 $\,\times\,$ 40 mm $^{2}\ (0.31 \lambda_{0}\times 0.41\lambda_{0})$ . The edge-to-edge separation between antennas is $0.052\lambda_{0}$ , and separation between feeds is $0.175 \lambda_{0}$ at 3.1 GHz. Detailed investigations of the parameters were performed, and the experimental results agree closely with the simulation results, demonstrating the feasibility of the proposed method.

Journal ArticleDOI
TL;DR: In this article, a triple-band microstrip-fed printed monopole antenna for wireless local area network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) is presented.
Abstract: A small and compact triple-band microstrip-fed printed monopole antenna for Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) is presented. The proposed antenna consists of a rectangular radiating patch with L- and U-shaped slots and ground plane. A parametric study on the lengths of the U- and L-shaped slots of the proposed antenna is provided to obtain the required operational frequency bands-namely, WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5 GHz). The proposed antenna is small (15 × 15 × 1.6 mm 3) when compared to previously well-known double- and triple-band monopole antennas. The simulation and measurement results show that the designed antenna is capable of operating over the 2.25-2.85, 3.4-4.15, and 4.45-8 GHz frequency bands while rejecting frequency ranges between these three bands. Omnidirectional radiation pattern and acceptable antenna gain are achieved over the operating bands.

Journal ArticleDOI
TL;DR: In this paper, a corrugated conical horn antenna using 3-D print technology or stereolithography is presented, which achieves a measured peak gain of 19.6 dBi at 16 GHz with a 1.92:1 VSWR from 11 to 18 GHz.
Abstract: We present the development of a Ku-band (10-16 GHz) corrugated conical horn antenna using 3-D print technology or stereolithography. The antenna is printed using acrylonitrile butadiene styrene (ABS), a thermoplastic, and then coated with conductive aerosol paint. The designed antenna achieves a measured peak gain of 19.6 dBi at 16 GHz with a 1.92:1 VSWR from 11 to 18 GHz. It is shown that 3-D printing is capable of producing sufficient feature sizes that make operation in the microwave/millimeter-wave (MMW) bands possible.

Journal ArticleDOI
TL;DR: In this paper, a low-cost method for generating circular polarization in a dielectric resonator antenna is proposed, which consists of four rectangular layers, each one being rotated by an angle of 30 degrees relative to its adjacent layers.
Abstract: A novel low-cost method for generating circular polarization in a dielectric resonator antenna is proposed. The antenna comprises four rectangular dielectric layers, each one being rotated by an angle of 30 ° relative to its adjacent layers. Utilizing such an approach has provided a circular polarization over a bandwidth of 6% from 9.55 to 10.15 GHz. This has been achieved in conjunction with a 21% impedance-matching bandwidth over the same frequency range. Also, the radiation efficiency of the proposed circularly polarized dielectric resonator antenna is 93% in this frequency band of operation

Journal ArticleDOI
Xuekang Liu1, Zhen-Ye Wang1, Yingzeng Yin1, Junyi Ren1, Jiaji Wu1 
TL;DR: In this paper, a compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna with lower wireless local area network (WLAN) coverage is proposed.
Abstract: In this letter, a compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna with lower wireless local area network (WLAN) coverage is proposed. The proposed MIMO antenna consists of two quasi-self-complementary monopoles, which are easy to achieve ultrawideband operation. By arranging two monopoles symmetrically, with their main radiation directions oppositely oriented, a UWB MIMO antenna with high isolation is proposed. This high isolation is achieved without using any other decoupling methods, which, totally, benefits from the monopoles' complementary and asymmetrical structures. The measured |S11| has the band of mainly covering 2.19-11.07 GHz except a little higher than -10 dB at 2.86-3.28 GHz, and with |S21| ≤ - 20 dB at most of the band. Since the proposed monopole has excellent inherent properties, a four-element UWB MIMO antenna with good isolation is also discussed.

Journal ArticleDOI
TL;DR: In this paper, a linearly polarized compact multiband MIMO antenna system for small mobile terminals is presented, which consists of two symmetric printed monopole antennas with edge-to-edge separation of 0.097 λ 0 at 900 MHz.
Abstract: This letter presents a study on linearly polarized compact multiband multiple-input-multiple-output (MIMO) antenna system for small mobile terminals. The MIMO antenna system consists of two symmetric printed monopole antennas with edge-to-edge separation of 0.097 λ0 at 900 MHz. Each antenna element has a capacitive feed and is composed of two twisted lines, a parasitic loop, and a shorting trip that generate five resonant modes around 900, 1800, 2100, 3500, and 5400 MHz, covering GSM850/900, DCS, PCS, UMTS, WLAN, and WiMAX frequency bands. Two inverted-L shaped branches and a rectangular slot with one circular end, etched on the ground plane, were introduced to improve the isolation between antenna elements. The isolation achieved is higher than 15 dB in the lower band and 20 dB in the upper bands, leading to an envelope correlation coefficient of less than 0.025. The simulated performance of the designed antenna system has been verified in the experiment.

Journal ArticleDOI
TL;DR: In this article, a substrate integrated waveguide (SIW) horn antenna loaded with air-via perforated dielectric slab for bandwidth enhancement is proposed, which can enhance the impedance bandwidth of the antenna in much degree.
Abstract: A substrate integrated waveguide (SIW) horn antenna loaded with air-via perforated dielectric slab for bandwidth enhancement is proposed in this letter. The narrow impedance bandwidth of the planar horn antenna is mainly resulting from the discontinuity between the substrate and air. By simply drilling air-vias with different diameters in the substrate extended from the horn aperture, a smooth transition from substrate to air can be achieved, which can enhance the impedance bandwidth of the antenna in much degree. Measured results show that the enhanced impedance bandwidth of 40% from 16 to 24 GHz is obtained with the return loss |S11| below -10 dB. In addition, stable radiation patterns are observed over the entire operating band.

Journal ArticleDOI
TL;DR: In this paper, a suitably designed, ultra-thin graded metasurface is used to provide an abrupt, inhomogeneous discontinuity to the electromagnetic field that compensates for the unwanted scattering created by the object.
Abstract: Using a suitably designed, ultra-thin graded metasurface, we demonstrate the possibility of hiding an arbitrarily shaped/sized object from an impinging plane wave. The metasurface is tailored to provide an abrupt, inhomogeneous discontinuity to the electromagnetic field that compensates for the unwanted scattering created by the object. The desired field distribution is generated based on the equivalence principle through reconstruction of the electric/magnetic fields at the metasurface location, resembling a flat conducting surface for an external observer. We apply this concept to hide electrically large, cylindrical (two-dimensional, 2-D) and spherical (3-D) domes at optical frequencies and discuss practical cloaking designs for microwave and terahertz regimes. The presented graded metasurface-based cloaks may find interesting applications as low-profile, tunable covers for low observability and noise reduction in wireless commutation systems.

Journal ArticleDOI
TL;DR: In this article, an anchor-shaped loop unit-cell structure for compact frequency selective surfaces (FSSs) with dual-bandstop behavior in two wireless local area network (WLAN) frequencies 2.4 and 5.0 GHz is proposed.
Abstract: In this letter, we propose an anchor-shaped loop unit-cell structure for compact frequency selective surfaces (FSSs) with dual-bandstop behavior in two wireless local area network (WLAN) frequencies 2.4 and 5.0 GHz. The proposed FSS possesses 230- and 300-MHz bandwidths with insertion loss less than ${-}$ 20 dB around the two central operating frequencies 2.4 and 5.0 GHz, respectively. In addition, the FSS exhibits excellent miniaturization with 0.065 $\lambda \times 0.076 \lambda$ unit cells, where $\lambda$ represents the free-space wavelength. Furthermore, the unit-cell structure provides a stable performance for both TE- and TM- polarizations under incident angles 0 $^{\circ}$ –60 $^{\circ}$ . A prototype of the proposed FSS is fabricated and measured. Good agreement between the simulated and measured results is obtained.

Journal ArticleDOI
TL;DR: In this article, a dual-band rectangular microstrip antenna (RMSA) is realized by two different single-slotted single-band RF antennas with slotted ground plane.
Abstract: A compact dual-band rectangular microstrip antenna (RMSA) is realized by two different single-slotted single-band rectangular microstrip antennas with slotted ground plane. Each open-ended slot in the single-slotted antenna is responsible to generate a wide impedance band that is shifted to lower frequencies by the effect of the ground slot. The length and position of each open-ended slot is varied to operate the antenna in a suitable resonant band (5.15-5.35 and 5.725-5.825 GHz). The proposed antenna meets the required impedance bandwidth, necessary for dual-band IEEE 802.11a WLAN application (5.125-5.395 and 5.725-5.985 GHz). The dimension of the antenna (12 × 8 × 1.5875 mm3) shows an average compactness of about 53.73% with respect to a conventional unslotted rectangular microstrip patch antenna.

Journal ArticleDOI
TL;DR: In this article, a low-RCS antenna is proposed based on the concept of the perfect absorber metamaterial (PAM) consisting of a periodic array of metallic dendritic structure and metallic square film etched on each face of a single substrate.
Abstract: Perfect absorber metamaterial (PAM) to reduce antenna radar cross section (RCS) is proposed. The novel low-RCS antenna is based on the concept of the PAM consisting of a periodic array of metallic dendritic structure and metallic square film etched on each face of a single substrate. The PAM processes high electromagnetic wave absorptivity for a wide incident angle. In the present letter, the PAM patterns are printed on the surface of a patch antenna to reduce the antenna RCS. It is demonstrated that, as compared to an antenna without the PAM, the proposed antenna RCS can be reduced drastically due to the fact that the PAM absorbs electromagnetic wave. Meanwhile, the proposed antenna can still maintain good radiation characteristics.

Journal ArticleDOI
TL;DR: In this paper, a fully planar wireless power transfer (WPT) system via strongly coupled magnetic resonances is presented, where both the transmitter and the receiver are planarized with the use of coplanar printed spiral coils (PSCs) and a printed loop.
Abstract: A fully planar wireless power transfer (WPT) system via strongly coupled magnetic resonances is presented. In it, both the transmitter and the receiver are planarized with the use of coplanar printed spiral coils (PSCs) and a printed loop. An equivalent circuit model of the proposed planar WPT system is derived to facilitate the design, and a flowchart is provided for the optimization of the system with given size constraints. To realize high peak power transfer efficiency, the quality factor of individual loop or resonator, the mutual coupling between resonators, and the frequency splitting phenomenon of the system are analyzed in addition to the effect of the input impedance of the system on the transmission efficiency. Furthermore, parallel current paths are created by applying auxiliary strips to the backside of the substrates and connecting to the prime resonators using vias to decrease the resistance and to increase the quality factor of the PSC resonators, and this in turn further improves the transfer efficiency of the proposed planar WPT system. The measured results show that the proposed WPT system is able to provide a stable wireless power transfer with up to 81.68% efficiency at a distance of 10 cm. The planar structure and the high transfer efficiency make the proposed design a suitable candidate for wireless power transfer of small portable electronic devices.

Journal ArticleDOI
TL;DR: In this paper, a planar patch antenna capable of multi-directional pattern reconfiguration is presented, which consists of a driven element surrounded by four parasitic elements that act either as reflector(s) or director(s), depending on the switching arrangement.
Abstract: A parasitic planar patch antenna capable of multi directional pattern reconfiguration is presented. The antenna structure consists of a driven element surrounded by four parasitic elements that act either as reflector(s) or director(s) depending on the switching arrangement. Beam reconfiguration is achieved by using four p-i-n diode switches where the effect of switching technique on the overall element performance is investigated numerically and experimentally. The proposed antenna achieves nine distinguished main beam angular positions. Moreover, the proposed antenna has achieved excellent realized gain levels at all configuration scenarios with a minimum value of 7 dBi. Simulation and measurement results show good agreement and promising applications of such antenna structure in enhanced WiMAX systems.

Journal ArticleDOI
TL;DR: In this article, a wideband compact circularly polarized (CP) patch antenna is proposed, which consists of a printed meandering probe (M-probe) and truncated patches that excite orthogonal resonant modes to generate wideband CP operation.
Abstract: In this letter, a wideband compact circularly polarized (CP) patch antenna is proposed. This patch antenna consists of a printed meandering probe (M-probe) and truncated patches that excite orthogonal resonant modes to generate a wideband CP operation. The stacked patch is employed to further improve the axial-ratio (AR) bandwidth to fit the 5G Wi-Fi application. The proposed antenna achieves 42.3% impedance bandwidth and 16.8% AR bandwidth, respectively. The average gain within the AR bandwidth is 6.6 dBic with less than 0.5 dB variation. This work demonstrates a bandwidth broadening technique of an M-probe fed CP patch antenna. It is the first study to investigate and exhibit the M-probe could also provide the wideband characteristics in the dielectric loaded patch antenna. The potential applications of the antenna are 5G Wi-Fi and satellite communication systems.

Journal ArticleDOI
TL;DR: In this article, a polarization-reconfigurable rectangular patch antenna for bandwidth enhancement is proposed, which has stair-slots on the ground and two p-i-n diodes are used for switching the antenna's polarization.
Abstract: A polarization-reconfigurable rectangular patch antenna for bandwidth enhancement is proposed. This antenna has stair-slots on the ground and two p-i-n diodes are used for switching the antenna's polarization in linear polarization (LP), left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The structure is concise and easy to optimize, and dc bias network is very simple. The measured impedance (-10-db S11) and 3-dB axial-ratio (AR) bandwidths are about 180 and 37 MHz, respectively, at the center frequency around 2.46 GHz for both LHCP and RHCP. Compared to the reference antennas (antenna with loop slots on the ground and antenna with L-shaped slots on the ground), the bandwidths of -10-dB S11 and 3-dB AR are greatly enhanced. The asymmetrical slotted ground excites TM10 and TM01 modes with different resonant frequency to generate CP radiation, and because of the stair-slots, instead of loop slots and L-shaped slots, the lower resonant frequency decreases and the higher one increases. Thus, the bandwidths are improved. The antenna has good switchable and radiation performances. It could be used for wireless local area network (WLAN) (2.4-2.5 GHz) in wireless communication systems.

Journal ArticleDOI
TL;DR: In this article, a new type of antenna in the millimeter frequency band is characterized in an anechoic chamber, where the index-varying flat plate generates an electromagnetic wave carrying orbital angular momentum.
Abstract: Electromagnetic waves bearing orbital angular momentum in the radio frequency range is a growing subject of study. The design of systems able to produce and/or to receive such waves is then of crucial importance. The aim of this letter is to characterize, in an anechoic chamber, a new type of antenna in the millimeter frequency band. The index-varying flat plate generates an electromagnetic wave carrying orbital angular momentum. We then extract the various modes from the radiated field.

Journal ArticleDOI
TL;DR: In this paper, a single-layer single-probe-feed asymmetrical fractal boundary microstrip antenna is considered for triband circular polarization (CP) operation, and four different structures (without-slot (Ant), rectangular (Ant2), fractal (Ant3), optimized-fractal slot (Ant4) are studied for multiband CP radiation.
Abstract: A novel single-layer single-probe-feed asymmetrical fractal boundary microstrip antenna is considered for triband circular polarization (CP) operation. Four different structures—without-slot (Ant1), rectangular (Ant2), fractal (Ant3), optimized-fractal-slot (Ant4)—are studied for multiband CP radiation. Perturbation in the structure for triband CP radiation is introduced by employing optimized asymmetrical Koch fractal curves as boundaries of a square patch and embedded rectangular slot. The generated 3-dB axial-ratio bandwidths of Ant 4 are 3.2%, 1.6%, and 3.0% at operating frequencies around 2.45, 3.4, and 5.8 GHz, respectively. Measured results that are in close agreement with the simulation results demonstrate that the proposed antenna is well suited for the WLAN/WiMAX wireless applications.