Wenting Li

Compact-Size Low-Profile Wideband Circularly Polarized Omnidirectional Patch Antenna With Reconfigurable Polarizations

A compact-size low-profile wideband circularly polarized (CP) omnidirectional antenna with reconfigurable polarizations is presented in this communication. This design is based on a low-profile omnidirectional CP antenna which consists of a vertically polarized microstrip patch antenna working in TM01/TM02 modes and sequentially bended slots etched on the ground plane for radiating horizontally polarized electric field. The combined radiation from both the microstrip patch and the slots leads to a CP omnidirectional radiation pattern. The polarization reconfigurability is realized by introducing PIN diodes on the slots. By electronically controlling the states of the PIN diodes, the effective orientation of the slots on ground plane can be changed dynamically and the polarization of antenna can be altered between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The proposed antenna exhibits a wide-operational bandwidth of 19.8% (2.09-2.55 GHz) with both axial ratio below 3 dB and return loss above 10 dB when radiates either LHCP or RHCP waves. Experimental results show good agreement with the simulation results. The present design has a compact size, a thickness of only 0.024λ and exhibits stable CP omnidirectional conical-beam radiation patterns within the entire operating frequency band with good circular polarization.

Polarization-Reconfigurable Circularly Polarized Planar Antenna Using Switchable Polarizer

A novel polarization-reconfigurable planar antenna is presented. The antenna consists of an electronically reconfigurable polarizer integrated with a printed slot. By changing the states of the p-i-n diodes on the polarizer, the linearly polarized (LP) waves radiated by the slot can be converted into either right-hand circularly polarized (RHCP) or left-hand CP (LHCP) waves. The polarizer contains 16 unit cells arranged as a

Inverted-S Antenna With Wideband Circular Polarization and Wide Axial Ratio Beamwidth

4\times 4

An Ultra-Wide-Band Tightly Coupled Dipole Reflectarray Antenna

array. The antenna radiates RHCP waves if the p-i-n diodes on the top side of the polarizer are switched ON, while LHCP waves are radiated if the p-i-n diodes of the bottom side of the polarizer are switched ON instead. The physical mechanisms of the antenna are discussed and the parametric study is carried out by full-wave simulations. To verify the concept, one prototype at 2.5 GHz is designed, fabricated, and measured. Good agreement between the measured and simulated results is obtained. The antenna achieves a gain ≥8.5 dBic in both RHCP and LHCP with an aperture efficiency of 70%. Advantages of the proposed design include electronically reconfigurable polarizations for RHCP or LHCP, low profile, low cost, high isolation between the dc bias circuit and RF signals, high power handling capability, and easy extension to large-scale arrays without increasing the complexity of the dc bias circuit. To the best of our knowledge, this is the first report of an electronically polarization-reconfigurable CP antenna with a single-substrate polarizer.

Wideband circularly polarized wide-beamwidth antenna using S-shaped dipole

A novel broadband circularly polarized (CP) antenna with wide axial ratio (AR) beamwidth is proposed. It is composed of two curved arms shaped like an inverted “S.” The mechanisms of wideband CP operation and wide AR beamwidth are explained. To validate the concept, a prototype at C-band is manufactured and measured. Experimental results confirm that the antenna achieves an impedance bandwidth of 63% and a CP bandwidth of 42%. Furthermore, maximum AR beamwidth of 140° is achieved and wide AR beamwidth can be maintained in a frequency bandwidth of 35% in nearly all elevation planes. In addition, the antenna has the advantage of being easily extended to arrays. A four-element array using the proposed antenna is investigated through both simulations and experiments, and achieves 60% CP bandwidth and wide AR beamwidth. The proposed inverted-S antenna can realize wide CP bandwidth and wide AR beamwidth, and can easily form wideband CP arrays.

Frequency-Agile Beam-Switchable Antenna

A novel ultra-wide-band tightly coupled dipole reflectarray (TCDR) antenna is presented in this paper. This reflectarray antenna consists of a wideband feed and a wideband reflecting surface. The feed is a log-periodic dipole array antenna. The reflecting surface consists of

Single-Layer Wideband Circularly Polarized High-Efficiency Reflectarray for Satellite Communications

26 \times 11

A wideband compact horizontally polarized omnidirectional antenna for 2G/3G/LTE

unit cells. Each cell is composed of a tightly coupled dipole and a delay line. The minimum distance between adjacent cells is 8 mm, which is about 1/10 wavelength at the lowest operating frequency. By combining the advantages of reflectarray antennas and those of tightly coupled array antennas, the proposed TCDR antenna achieves ultra-wide bandwidth with reduced complexity and fabrication cost. A method to minimize the phase errors of the wideband reflectarray is also developed and the concept of equivalent distance delay is introduced to design the unit cell elements. To verify the design concept, a prototype operating from 3.4 to 10.6 GHz is simulated and fabricated. Good agreement between simulated and measured results is observed. Within the designed frequency band, the radiation pattern of the TCDR antenna is stable and the main beam of the antenna is not distorted or split. The side lobe levels of the radiation patterns are below −11.7 dB in the entire operating band. It is the first time a tightly coupled reflectarray is reported.

A Novel Ultra-Wideband Transmitarray Design Using Tightly Coupled Dipole Elements

This paper presents a novel circularly polarized (CP) printed antenna with wide bandwidth and wide axial ratio (AR) beamwidth. The presented antenna is realized by bending a linearly polarized dipole into “S” shape with variable line width, which achieves circularly polarized radiation. Key parameters in designing such an “S” antenna are discussed and studied. It is found that this “S” antenna has some similar features to the linear polarized dipole, such as the feeding method, the radiation pattern in some main planes and nearly omnidirectional radiation in one main plane. To verify its performance, a ground plane backed inverted-S antenna is fabricated and characterized. Measured results confirm that the proposed antenna has good CP radiation, wide CP beamwidth from 4 to 6 GHz. The antenna is promising for applications in Global Navigation Satellite Systems (GNSS), and wideband wide-angle-scanning CP phased arrays.

Wideband dual circularly polarized beam-scanning array for Ka-band satellite communications

A novel antenna with both frequency and pattern reconfigurability is presented. The reconfigurability is achieved by integrating an active frequency selective surface (AFSS) with feed antenna. The smart FSS comprises a printed slot array loaded by varactors. A novel dc biasing arrangement is proposed to feed the slots vertically so that the unwanted effects caused by bias lines are minimized. A monopole antenna is designed to illuminate the AFSS. The resulting structure can operate in a frequency tuning range of 30%. By reconfiguring the different sections of active FSS cylinder into a transparent or reflector mode, the omnidirectional pattern of the source antenna can be converted to a directive beam. As an illustration, half of the AFSS cylinder is successively biased, enabling the beam switching to cover the entire horizontal plane over a range of frequencies. An antenna prototype was fabricated and measured. Experimental results demonstrate the capability of providing useful gain levels and good impedance matching from 1.7 to 2.3 GHz. The antenna offers a low-cost, low-power solution for wireless systems that require frequency and beam reconfigurable antennas. The proposed design consumes about 1000 times less dc power than the equivalent narrowband beam-switching antenna design using p-i-n diode-loaded AFSS.