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A rectangular dielectric resonator antenna (DRA) with multiple polarization modes is proposed in this study. The antenna is fed by adjustable feed network composed by Wilkinson power divider and tunable phase shift elements. On this reconfigurable design, it can operate in left‐handed circular polarization, right‐handed circular polarization, and linear polarization (LP) modes. The 3‐dB axial ratio bandwidth of 30.2% for CP modes and impedance bandwidth of 33.3% for CP states are obtained. The maximum gains are 5.7 dBic and 6.34 dBi for CP and LP states. A prototype is built on the FR4 substrate with ideal switches and tested to validate the design. Simulated and measured results showed good agreement on the polarization reconfigurable performances of interest. The proposed DRA can be applied to modern wireless system with polarization diversity requirements. [ABSTRACT FROM AUTHOR]

Abstract: A coplanar waveguide fed polarization reconfigurable monopole antenna is proposed in this letter. The proposed antenna consists of L‐shaped stubs placed on either side of a monopole, two p‐i‐n diodes and a slot in the ground plane. In the proposed antenna structure, the switching element is not directly connected to the feed line. Depending on the switching state of the p‐i‐n diodes, the antenna either radiates left/right circular polarization or linear polarization. To validate the proposed design, the antenna was fabricated and its performance was measured. Since the ground plane is electrically small, the effect of the cable and SMA connector on the performance of the antenna is also investigated. The measured impedance bandwidth is 66.78% (3.67 GHz to 7.35 GHz) and the axial ratio bandwidth is 13.62% (4.24‐4.86 GHz) for circular polarization and 23.61% (3.81‐4.83 GHz) impedance bandwidth for linear polarization. [ABSTRACT FROM AUTHOR]

A novel cuboid quadrifilar helical antenna (QHA) with polarization and pattern reconfigurabilities is presented. The proposed antenna consists of a reconfigurable radiator and a switchable feeding network. The radiator combines two individual QHAs in a cuboid, which can be alternatively activated. The feeding network provides switchable quadrature excitations to the radiator. By controlling the p-i-n diodes on the radiator and the feeding network, four working states including both polarization and pattern agilities are achieved. The polarization of the antenna can be switched between two orthogonal circular polarizations, and the radiation pattern can be changed between broadside and backfire modes. A prototype designed to operate at 0.9 GHz band is developed and measured. The measured results validated that the antenna achieved the four working states with stable wide-beam radiation patterns. Moreover, the proposed antenna obtained wide impedance and axial-ratio bandwidths (36.2% and 22%, respectively) in a compact size ( $0.26\lambda _{0}\times 0.26\lambda _{0}\times 0.25\lambda _{0}$ ). The proposed antenna which has attractive electrical characteristics can be applied to various wireless communications, e.g., RFID readers, subway, and railway communications. [ABSTRACT FROM AUTHOR]

A novel polarization-reconfigurable mechanism based on a polarization-rotation artificial magnetic conductor (PRAMC) structure is proposed. A new polarization-reconfigurable antenna is designed by combining a PRAMC-based multipolarized dipole antenna with a RFIC switch-based network, in which three polarization states of right-handed, left-handed circular polarization (RHCP, LHCP) and +45^\circ linear polarization (LP) can be realized by controlling the dc bias of the switches accordingly. The multipolarization antenna is well designed for offering three polarization states. A large 3-dB axial ratio (AR) bandwidth of 15.5%, a wide 3-dB AR beamwidth for CP states and a large cross-polarization isolation of more than 50 dB for LP state together with a broad impedance bandwidth of 20.5% are obtained. A switch network is used to generate three feeding modes, and the performance of the RF-integrated circuit (RFIC) switches is experimentally verified. A prototype of the proposed polarization-reconfigurable antenna is fabricated and tested. Good agreements between the measured and simulated results are observed, which indicates good performances of the proposed antenna. [ABSTRACT FROM PUBLISHER]

This communication introduces a polarization reconfigurable wideband circularly polarized (CP) antenna, which consists of four radiating arms connected to a reconfigurable feeding network. The four radiating arms excited by the feeding network are able to generate wideband CP waves with bidirectional radiation patterns in free space. In order to increase the gain and obtain a broadside radiation pattern, the proposed antenna is placed above a metallic reflector with the distance of quarter wavelength at the center frequency. In addition, polarization reconfigurability is realized by utilizing PIN diodes in the feeding transmission lines such that left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) modes can be selectively excited by controlling the on/off states of the PIN diodes. The proposed antenna exhibits a wide impedance bandwidth of 80% and an overlapped axial ratio (AR) bandwidth of 23.5% for both modes. The antenna gain is stable across the operating bandwidth with the peak gain of 4.8 dBic. The antenna has a wide AR beamwidth of 90°. The presented work is suitable for GPS, CNSS, or RFID applications. [ABSTRACT FROM PUBLISHER]

This paper proposes a reconfigurable square-patch antenna with polarization diversity. The proposed antenna consists of a square radiating patch and a Y-shaped feed structure with two PIN diodes. The shape of the feed structure can be changed by adjusting the bias states of the two PIN diodes, which helps switch between two orthogonal linear polarizations. The polarization diversity characteristic is validated by the simulated current distribution and the measured radiation pattern. [ABSTRACT FROM AUTHOR]

This paper introduces a polarization reconfigurable wheel-shaped antenna with wide bandwidth and conical-beam radiation pattern. A wideband circular-monopolar patch surrounded by eight reconfigurable coupling loop stubs can generate conical-beam radiation patterns with different polarizations. This polarization reconfigurable characteristic is realized by controlling PIN diodes on the coupling loop stubs. The center-fed circular patch operates with the vertically-polarized conical-beam radiation and the coupling loop stubs radiate the horizontally-polarized wave propagation. With choosing proper magnitudes and phase differences between the two orthogonal radiations from the monopolar patch and the loop stubs, a circularly-polarized conical-beam radiation can be obtained. In addition, the presence of a back reflector yields a wide axial ratio bandwidth, enhances the front-to-back ratio of the radiation pattern, and avoids EM interferences between DC biasing lines and the antenna. This proposed antenna can generate three types of polarizations with the conical-beam radiation pattern including vertical polarization, left-handed circular polarization, and right-handed circular polarization by controlling the PIN diodes. Measured impedance and axial ratio bandwidths are 28.6% (3.45 to 4.6 GHz) and 15.4% (3.6 to 4.2 GHz), respectively, for the two CP modes. The maximum CP gain is 4.4 dBic. Furthermore, a dual-band operation (3.35 to 3.44 GHz and 4.5 to 4.75 GHz) can be observed for the LP mode. The antenna can operate at the downlink of standard C band (3.625 to 4.2 GHz) for geostationary satellite communication. [ABSTRACT FROM PUBLISHER]

The performances of a quasilumped coupler with a pair of capacitors are first described. By varying the capacitance value of the capacitors, the coupler can operate at three different modes, including uncoupled-line mode, quadrature hybrid mode, and T-junction power divider mode. Based on the coupler design, a microstrip antenna with switchable polarization is developed and implemented. Experimental results demonstrate that the reconfigurable antenna can provide two linear polarizations and one circular polarization at one frequency. In addition, the antenna operating at each polarization state has good impedance matching and broadside radiation with low cross polarization. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:471-474, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27374 [ABSTRACT FROM AUTHOR]

This paper presents a new kind of microstrip reflectarray antenna those polarization could be reconfigurable among all polarization states instead of some fixed states for dual- or multipolarized antenna. The mechanism for polarized variability is so simple that only mechanical rotation is needed. The complete theoretical analysis is given as well as a specific design sample to verify this method. At designed frequency of 10 GHz and in case of circularly polarized (CP) radiation, experimental results in agreement with simulated ones exhibit -26-dB cross-polar level (CPL), -13-dB side-lobe level, 13.5° half-power beamwidth, and 17.3-dBi gain corresponding to about 40% aperture efficiency. It also possesses 8% bandwidth from 9.5 to 10.3 GHz for CPL less than -15 dB. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1429–1432, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21640 [ABSTRACT FROM AUTHOR]