Ya-Qing Wen

A Wide-Angle Scanning and Low Sidelobe Level Microstrip Phased Array Based on Genetic Algorithm Optimization

In order to obtain a wide-angle scanning and low sidelobe level (SLL) microstrip phased array with a finite metal ground, a novel microstrip phased array based on microstrip magnetic dipole is presented in this communication. Microstrip magnetic dipoles are employed as the driven elements in the phased array. Meanwhile, coupling patches are embedded between the adjacent driven elements, and coupling energy is transferred between driven elements by the coupling patches. Strong coupling has been constructed between elements as the driven element spacing is only about 0.35 λ . With the influence of adjacent elements, the 3-dB beamwidth (BW) of each active element can reach over ±80° in the elevation plane. From simulation and measurement, the main lobe scanning ranges of an 8-element and a 16-element phased arrays can both extend over ±80° in the elevation plane with a gain fluctuation less than 3 dB. Furthermore, in order to keep the SLL low in the scanning, especially at the low elevation angles, genetic algorithm (GA) has been used, and the SLL has been decreased to the value of -9 dB in the full scanning range of ±77° for the eight-element array.

Wide-Beam SIW-Slot Antenna for Wide-Angle Scanning Phased Array

In order to enhance the scanning range of planar phased arrays, a planar substrate integrated waveguide slot (SIWslot) antenna with wide beamwidth is proposed in this letter. The proposed antenna is fabricated on a single-layer substrate, which is fully covered with a metal ground on the back. The SIW works like a dielectric-filled rectangular waveguide working in the TE10 mode. There are four inclined slots etched on the top metal layer following the rules of rectangular waveguide slot antenna. The electric fields in the slots work as equivalent magnetic currents. As opposed to normal microstrip antennas, the equivalent magnetic currents from the slots over a larger metal ground can radiate with a wide beamwidth. Its operating bandwidth is from 5.4 to 6.45 GHz with a relative bandwidth of 17.7%. Meanwhile, the 3-dB beamwidth in the xz-plane is between 130° and 148° in the whole operating band. Furthermore, the SIW-slot element is employed in a 1 × 8 planar phased array. The measured results show that the main lobe of phased array can obtain a wide-angle scanning from -71° to 73° in the whole operating band.

A novel polarization reconfigurable antenna based on transmission line theory

A novel polarization reconfigurable antenna based on the transmission line theory is proposed. The antenna contains two side-fed microstrip patches that are placed vertically and horizontally, respectively and fed using a T-shaped branch line. The proposed antenna achieves vertical polarization with the horizontal microstrip patch or horizontal polarization with the vertical microstrip patch, respectively. The antenna works at 5.8 GHz. The measurements match well with the simulations. This design demonstrates a useful feature of the proposed antenna for wireless communication applications.

Low profile circularly-polarized microstrip crossed antenna with wide beamwidth

A CP (Circularly-polarized) wide-beam microstrip antenna is proposed. A microstrip patch crossed dipole is inset in a slot with corresponding shape. Electric current is generated on the patch dipole, and electric field is generated in the slot. The radiation originated from the electric current is horizontal-polarization, and the radiation originated from the electric field is vertical-polarization. The synthetical radiation will obtain a CP radiation pattern. The result shows that the antenna can obtain its 3dB beamwidth wider than 134° at both x-z plane and y-z plane. Besides, the RHCP (Right-Hand Circularly-Polarized) beamwidth with AR<;3dB of the antenna is wider than 135° at both x-z plane and y-z plane. Meanwhile, the antenna is low profile. The thickness of the antenna is only 0.018λο. At last, the front-to-back ratio is high because there is an intact metal ground on the back of the antenna.

Planar Microstrip Endfire Antenna With Multiport Feeding

Design of a planar microstrip endfire antenna with three feeding ports is presented in this letter. There are five layers in the vertical direction of the antenna, which are the radiating patches, the upper substrate, the metal ground, the bottom substrate, and the feeding microstrip lines, respectively. The patches contain the driven element and the second elements. There are four feeding points on the driven element, and each point is connected to the feeding microstrip line on the bottom layer by metal vias. Strong coupling is established by the connection between the driven and the second elements through the coupling bridges of microstip lines and metal vias. While a different port is excited, a different kind of electric field distribution is generated on the antenna. Correspondingly, a different kind of radiation pattern is obtained. Simulated and measured results show that, in the xz-plane, the antenna excited by the three ports in turn can attain a bidirectional endfire radiation pointing at ± 80° and two directional endfire radiations pointing at ± 81°, respectively.

Wide-angle scanning phased array based on microstrip magnetic dipole Yagi sub-arrays

In order to extend scanning range of a microstrip planar phased array, a novel array structure based on microstrip magnetic dipole Yagi (MMD-Yagi) sub-arrays is presented in this paper. The MMD-Yagi sub-array antenna has a radiation pattern with double main lobes, which results in the coverage of 3dB beam-width reaching up to ±75°. A microstrip phased array composed of 8 MMD-Yagi sub-arrays with a large metal ground can scan its main lobe from -78° to +77° in the elevation plane with a gain fluctuation less than 4dB.

A wide-angle scanning array based on the image theory and time reversal synthesis method

A wide-angle scanning array based on the image theory and time reversal synthesis method (TRSM) is proposed. The main lobe of the array can scan from -75° to +75° with a gain fluctuation less than 4dB. It shows that the image theory can be used to design wide-beam antenna and the TRSM can be used to optimize the wide-angle scanning array efficiently.

Research on the configuration of time reversal mirror in time reversal beamforming system

The combination of the time reversal (TR) which is attached to inherently temporal and spatial focusing property and MIMO can increase the throughput of the system and reduce the interference as well. Further, TR beamforming (TRBF) has been mentioned as one of the promising technologies in future massive MIMO communication system. The intention of this paper concentrates on the configuration of TR mirror in TRBF system. Results reveal that appropriate configuration is a pivotal strategy to economize on energy.

Enhanced resolution of slots based on time reversal method

Imaging techniques allow probes to scan the near-field of objects to get the image of the objects. However, the near-field systems are prone to signal corruption from unwanted multipath signals. As we know, time reversal techniques can overcome the multipath effect in getting the independence of signals. This paper presents a novel method for enhancing the resolution of slots. With the Fresnel-Kirchhoff diffraction formula, a time reversal imaging system is founded to analyze the performance of imaging. The results show the resolution of slots is enhanced by time reversal imaging method.

Compact broadband ZOR and FOR antenna with epsilon negative transmission line

A zeroth-order resonance (ZOR) and first-order resonance (FOR) antenna based on the metamaterial is presented in this paper. The epsilon negative transmission line (ENG-TL) includes one meander line for realizing shunt inductance. The antenna is fed by an asymmetric co-planar waveguide (ACPW). The asymmetry of this structure brings about ZOR and FOR mode, which are merged into one passband to achieve a wideband performance. The ZOR and FOR antenna with high gain has a wide bandwidth of 1.60-3.34 GHz and a small size of 0.2λ×0.13λ.