Qingsheng Zeng

Wideband Fabry-Perot Resonator Antenna With Two Complementary FSS Layers

This paper presents a novel design of a Fabry-Perot (FP) resonator antenna with a wide gain bandwidth in X band. The bandwidth enhancement of the antenna is attributed to the positive reflection phase gradient of an electromagnetic band gap (EBG) structure, which is constructed by the combination of two complementary frequency selective surfaces (FSSs). To explain well the design procedure and approach, the EBG structure is modeled as an equivalent circuit and analyzed using the Smith Chart. Experimental results show that the antenna possesses a relative 3 dB gain bandwidth of 28%, from 8.6 GHz to 11.4 GHz, with a peak gain of 13.8 dBi. Moreover, the gain bandwidth can be well covered by the impedance bandwidth for the reflection coefficient ( S 11) below -10 dB from 8.6 GHz to 11.2 GHz.

Wideband Fabry–Perot Resonator Antenna With Two Layers of Dielectric Superstrates

This letter presents a new design of a Fabry-Perot resonator antenna (FPRA) with a wide gain bandwidth. A double-layered dielectric superstrate, which produces a reflection phase curve versus frequency with a positive slope, is used as a partially reflective surface (PRS) to enhance the bandwidth of the FPRA. For a physical insight, the PRS is analyzed by using the transmission line theory and Smith Chart. Experimental results demonstrate that the antenna has a 3-dB gain bandwidth over 13.5-17.5 GHz, relatively 25.8%, with a peak gain of 15 dBi. Furthermore, the gain band is overlapped well by the impedance band for the reflection coefficient ( S11) less than -10 dB.

NEW DIELECTRIC 1-D EBG STRUCTURE FOR THE DESIGN OF WIDEBAND RESONATOR ANTENNAS

In this paper, we propose a method to use 1-D dielectric slabs, instead of metallic Frequency Selective Surfaces (FSSs), to produce Partially Re∞ective Surfaces (PRSs) with positive re∞ection phase gradients. The structure is realized by a single kind of dielectric substrate. It is modeled as cascaded transmission lines and then analyzed by virtue of the Smith Chart from the perspective of impedance transformation. A PRS designed by this approach is then applied to the realization of a wideband EBG resonator antenna operating at Ku band which is fed by a slot-coupled patch antenna. The calculated results indicate that the antenna possesses a relative 3dB gain bandwidth of 22%, from 14.1GHz to 17.6GHz, with a peak gain of 17dBi. The impedance bandwidth for the re∞ection coe-cient (S11) less than i10dB, is from 14GHz to 17.7GHz, well covering the 3dB gain bandwidth. A prototype has been fabricated and measured, and the experimental results well validate the simulation. The design method developed here is signiflcantly efiective, and can be easily adopted for antenna designs at other frequencies.

Compact Quad-Mode Bandpass Filter Based on Quad-Mode DGS Resonator

In this letter, a quad-mode bandpass filter is built up based on a novel quad-mode defected ground structure (DGS) resonator which has two symmetric planes. The odd-/even-mode theory is applied to analyze the operating principle of the four resonances with their equivalent circuit models. The four resonances can be effectively tuned by adjusting the corresponding dimensions. The fabricated filter has a center frequency of 2.45 GHz and a wide stopband up to 7.8 GHz with a rejection below -30 dB, which extends to at least 30 GHz below -16 dB. Particularly, the filter exhibits an excellent attenuation slope of 302 dB/GHz in the upper passband transition.

Antipodal linearly tapered slot antenna array for millimeter-wave base station in massive MIMO systems

For massive MIMO systems, it is very challenging to have the large-scale antennas for a compact base station. This paper presents a 36 sub-sectors for a compact millimeter-wave base station. The antenna array for each sub-sector is comprised of 16 planar high-gain dielectric-loaded antipodal linearly tapered slot antenna (ALTSA) elements arranged in a 4×4 configuration. Down to 36 feed ports are required in a base station with 36×16 antennas. The realized gain of the antenna array is 25.6 dBi, and the half-power beam widths (HPBW) are 10.7° and 5.3° in H-plane and E-plane, respectively.

INTEGRATED ULTRA-WIDEBAND PLANNAR MONOPOLE WITH CYLINDRICAL DIELECTRIC RESONATOR ANTENNAS

An ultra-wideband (UWB) planar monopole antenna integrated with a narrow-band (NB) cylindrical dielectric resonator antenna (DRA) is presented. The proposed antenna consists of a UWB monopole excited by a coplanar waveguide (CPW) transmission line, acting as a ground for a DRA excited by a slot. The mode HEM11- is excited in the NB DRA. To validate the concept of integration, an antenna is fabricated and measured. The measured results demonstrate that the UWB antenna provides a 2 : 1 voltage standing wave ratio (VSWR) bandwidth for 3.05{11GHz, integrated with a dual-band NB antenna. Moreover, the two ports have the same polarization and a reasonable isolation (less than i10dB) between each other. This is a promising candidate for applications in cognitive radio, where the UWB antenna can be used for spectrum sensing and the NB antenna for communication operation.

Integrated Ultrawideband/Narrowband Rectangular Dielectric Resonator Antenna for Cognitive Radio

An integrated ultrawideband (UWB) and narrowband (NB) rectangular dielectric resonator antenna (DRA) is presented. The proposed antenna consists of a UWB rectangular DRA excited by a bevel-shaped patch and an NB DRA excited by a strip. The measured results demonstrate that the UWB and NB antenna provides a 2:1 voltage standing wave ratio (VSWR) bandwidth for 2.4-12 and 2.3-4.5 GHz, respectively, with the same polarization. Moreover, two symmetrical short-circuited strips are introduced to improve the isolation between the two ports. This can be a suitable candidate for applications in cognitive radio, where the UWB antenna can be used for spectrum sensing and the NB antenna for communication operation.

A WIDEBAND HIGH-GAIN STACKED CYLINDRICAL DIELECTRIC RESONATOR ANTENNA

A new wideband and high-gain dielectric resonator antenna (DRA) is proposed. Three cylindrical dielectric resonators (DRs) with difierent materials and difierent sizes and a metallic cylinder are designed to obtain a wideband bandwidth and a high gain. The stacked structure provides a wideband bandwidth, and the cavity formed by the metallic cylinder provides a high gain. The measured results demonstrate that the proposed DRA has a wide bandwidth from 5.4 to 7.0GHz with VSWR less than two and a gain around 11dBi, covering the frequency range of 26%. The experimental and numerical results are discussed and compared with each other, showing a good agreement between them.

Characterization of a transient wave reflected from a lossy half space using numerical inversion of laplace transform

In this article, one method based on numerical inversion of Laplace transform is applied to the transient analysis of the reflected wave from a conducting interface for both vertical and horizontal incidence. This method is applicable to any relative dielectric constant and incident angle, leads to good accuracy in both late and early time, and has a simple algorithm, short calculation time, small required memory size, readily controlled error and wide application range. Comparison between our results and the published results confirms the correctness and effectiveness of this approach.

A Compact Dual-Band Beam-Sweeping Antenna Based on Active Frequency Selective Surfaces

A dual-band beam-sweeping antenna based on two independent cylindrical active frequency selective surfaces (AFSSs) is proposed in this paper. This antenna is composed of a dual-band omnidirectional monopole antenna operating at 2.45 and 5.2 GHz and two cylindrical AFSS screens. The dual-band omnidirectional monopole antenna is designed as a radiating source and surrounded by the proposed two cylindrical AFSS screens. The unit cells of the two proposed AFSS screens consist of two metallic crosses connected by a pin diode vertically. By switching the pin diodes, the transmission and reflection characteristics of unit cell of the two AFSS are investigated, respectively, at their own operating frequency. This leads to the variation of the radiation pattern when the cylindrical AFSS screens are loaded around the monopole antenna. Therefore, by switching the pin diodes with specified combinations, the dual-band beamforming antenna with multiple discrete states can be achieved at 2.45 and 5.2 GHz.