Lu-Yang Ji

A Reconfigurable Partially Reflective Surface (PRS) Antenna for Beam Steering

The design of a novel partially reflective surface (PRS) antenna with the capability of beam steering is presented in this paper. The beam steering is realized by employing a reconfigurable PRS structure to achieve a changeable reflection phase as well as using a phased array as the source to excite the PRS antenna. A prototype antenna including the biasing network is fabricated and measured. It achieves a consistent beam steering from - 15° to 15° with respect to the broadside direction across an overlapped frequency range from 5.5 to 5.7 GHz with measured realized gains over 12 dBi. Good agreement between the simulated and measured results for the input reflection coefficients and radiation patterns is achieved, which validates the feasibility of the design principle. Compared with other beam steering PRS antennas, the proposed one enables a larger beam steering angle with comparable gains, requires a simpler biasing network, and is more compact.

A Wideband Polarization Reconfigurable Antenna With Partially Reflective Surface

A novel partially reflective surface (PRS) antenna is proposed, which can electronically alter its polarization between linear polarization, left-hand circular polarization (CP), and right-hand CP. The antenna consists of a shorted annular patch antenna as the source, a PRS structure to enhance the gain, and a reconfigurable Wilkinson power divider as the feed network. Four p-i-n diodes are inserted into each branch of the power divider to change its electrical length. By switching the p-i-n diodes ON and OFF, a phase difference of 0°, 90°, or -90° can be realized at the two output ports of the feed network, hence enabling the antenna to radiate either a linearly polarized signal or left/righthanded circularly polarized signal. A prototype antenna with the biasing network is designed, fabricated, and measured. Good agreement between the simulated and measured results is achieved. Measurement results show that the proposed antenna has an overlapped 10-dB impedance bandwidth and 3-dB axial-ratio bandwidth of 4.7-5.36 GHz (13.1%). The average realized gains are ~9 dBi/dBic, which remain reasonably stable for different polarizations. The proposed antenna outperforms most of the reported polarization reconfigurable antennas for its wide bandwidth and relatively high gain.

Compact SIW Annular Ring Slot Antenna With Multiband Multimode Characteristics

A substrate-integrated waveguide (SIW) cavity-backed annular ring slot antenna with multiband multimode characteristics is proposed in this communication. The antenna consists of an SIW cavity and an annular slot on top surface as the radiator. Two patch-like radiation patterns and one monopolar radiation pattern at three different frequencies are excited by the single fed antenna. Moreover, each operating frequency can be individually adjusted. A prototype is fabricated and measured to validate the theoretical analysis. Good agreement between the simulated and measured results of the input reflection coefficients and radiation patterns is achieved. Compared with other designs, the proposed antenna has features of simple structure, multiband multimode and frequency-tunable characteristics.

Wideband Circularly Polaried Cross Bowtie Dipole Antenna with Axial-Ratio Bandwidth Enhancement

A wideband circularly polarized (CP) cross-dipole antenna is proposed for wireless applications. In this design, four parasitic square patches are utilized around the radiation patch to enhance the Axial-ratio (AR) bandwidth. By employing the bowtie-shape dipoles, the proposed antenna can achieve a wide impedance bandwidth. Meanwhile, by integrating with a curved-delay line which provides a 90◦ phase difference, the proposed antenna can radiate a CP pattern. A prototype is calculated, fabricated, and measured. Good agreement between the simulated and measured results is achieved. The measured results show an impedance bandwidth for VSWR ≤ 2 of 47.73% (1.93– 3.14 GHz) and a 3-dB AR bandwidth of 42.8% (2.00–3.09 GHz).

Broadband partially reflective surface antenna with tapered corrugated ground

This paper proposes a broadband Partially Reflective Surface antenna. It consists of a U-slot microstrip antenna as the source, an FR4 superstrate as the partially reflective surface, and a tapered corrugated ground structure. By employing the corrugated ground, the 3dB gain bandwidth is improved from 17% to 24% with the maximum realized gain and the 10dB impedance bandwidth unchanged. Therefore, the corrugated ground structure can be a good candidate to enhance the gain bandwidth of PRS antennas.

Wideband feeding method for full-wave dipole

This paper introduces a wide-band feeding method for full-wave dipole antennas. A full-wave dipole is designed to cover the band from 698 MHz to 960 MHz for cellular base station applications. Its matching circuit consists of a ladder-type filter design and a quasi-quarter-wavelength resistance transformer. The proposed matching circuit can provide balanced feeding as a balun and has a compact size. The matching circuit is designed and optimized using a circuit theory model and then physically realized using microstrip lines based on full-wave simulation. The simulated reflection coefficient |S11| is < −15 dB across the entire target band, exhibiting a bandwidth of 32%.

Miniaturization of base-station antenna element

A miniaturized ±45° dual-polarized magnetoelectric dipole antenna element for cellular base-station application is proposed in this paper. The antenna element is realized by exciting a pair of planar electric dipole antennas and a pair of quarter-wave vertically shorted patch antennas simultaneously, which performs as crossed electric and magnetic dipoles. The corners of the planar electric dipole antennas are truncated for miniaturization purpose. The height of the walls surrounding the dipole is optimized for stable radiation patterns. As a result, the proposed antenna element can have the size reduced from 0.8λ0 to 0.59λ0, yet achieving a similar performance, where λ0 is the wavelength at the center frequency.

WIDEBAND OMNIDIRECTIONAL CIRCULARLY POLARIZED PATCH ANTENNA WITH MULTI-RESONANT STRUCTURE

A wideband omnidirectional circularly polarized (CP) patch antenna is proposed in this paper. The proposed antenna is composed of a disk-loaded coaxial probe and four pairs of modified Γ-shaped strips loaded with shorting pins. Each pair of modified Γ-shaped strips consists of an inner Γ-shaped strip and an outer Γ-shaped strip. The approach employed in this design for improving the operating bandwidth is to add an inner Γ-shaped strip and make it couple to the outer one. By introducing the two coupled Γ-shaped strips, two different monopole modes can be achieved simultaneously and controlled separately by two different corresponding parts of these two Γ-shaped strips, respectively, and they can be merged to realize a wide-band impedance matching. Meanwhile, two minimum axial ratio (AR) points around the resonances of the antenna are excited by the coupled Γshaped strips, and they can be reallocated closely to each other for wide AR bandwidth. The measured results show that the proposed design has a 10-dB impedance bandwidth of 22.7% (2.26–2.84 GHz), 3-dB AR bandwidth of 33.6% (2.1–2.95 GHz) and low profile of 0.1λ0 (λ0 is the free-space wavelength at center frequency). In addition, a parametric discussion is conducted to further verify the proposed design.

A single-layer wideband reflectarray with sub-wavelength phase-shifting elements

A single-layer wideband reflectarray antenna employing sub-wavelength phase-shifting elements is presented. The element is composed of double concentric square meander line rings and its size is a fifth of a wavelength. By changing the length of the meander line, a phase variation range of about 360° is achieved with an almost constant slop across the 9 to 11 GHz. Using this element, a 48 × 48 - element reflectarray antenna is designed. A measured 1.5-dB gain bandwidth of 18 % is achieved.

Array-Fed Beam-Scanning Partially Reflective Surface (PRS) Antenna

A beam-scanning partially reflective surface (PRS) antenna is presented in this paper. By employing a reconfigurable feed network to a two-element phased array source, the PRS antenna can realize beam steering between −10◦ and 10◦ with respect to the broadside direction across an overlapped frequency range from 5.35GHz to 5.76GHz. Good agreement between the simulated and measured results is achieved, which validates its capability to be a good candidate for the modern communication systems.