Chun-Xu Mao

Multimode Resonator-Fed Dual-Polarized Antenna Array With Enhanced Bandwidth and Selectivity

A novel design concept of multimode filtering antenna, which is realized by integrating a multimode resonator and an antenna, has been applied to the design of dual-polarized antenna arrays for achieving a compact size and high performance in terms of broad bandwidth, high-frequency selectivity and out-of-band rejection. To verify the concept, a 2×2 array at C-band is designed and fabricated. The stub-loaded resonator (SLR) is employed as the feed of the antenna. The resonant characteristics of SLR and patch as well as the coupling between them are presented. The method of designing the integrated resonator-patch module is explained. This integrated design not only removes the need for separated filters and traditional 50 -Ω interfaces but also improves the frequency response of the module. A comparison with the traditional patch array has been made, showing that the proposed design has a more compact size, wider bandwidth, better frequency selectivity, and out-of-band rejection. Such low-profile light weight broadband dual-polarized arrays are useful for space-borne synthetic aperture radar (SAR) and wireless communication applications. The simulated and measured results agree well, demonstrating a good performance in terms of impedance bandwidth, frequency selectivity, isolation, radiation pattern, and antenna gain.

An Integrated Filtering Antenna Array With High Selectivity and Harmonics Suppression

In this paper, a new design of an antenna array with integrated functions of filtering, harmonics suppression, and radiation is proposed. The device employs a multi-port network of coupled resonators, which is synthesized and designed as a whole to fulfill the functions of filtering, power combination/division, and radiation. The 50-Ω interfaces between the cascaded filter, power divider, and antenna in traditional RF front-ends are eliminated to achieve a highly integrated and compact structure. A novel resonator-based four-way out-of-phase filtering power divider is proposed and designed. It is coupled to the patch array, rendering a fourth-order filtering response. The coupling matrix of the resonator network is synthesized. The physical implementations of the resonators and their couplings are detailed. Compared to a traditional patch array, the integrated filtering array shows an improved bandwidth and frequency selectivity. In addition, the harmonic of the antenna array is suppressed due to the use of different types of resonators. To verify the concept, a 2×2 filtering array at S-band is designed, prototyped, and tested. Good agreement between simulations and measurements has been achieved, demonstrating the integrated filtering antenna array has the merits of wide bandwidth, high frequency selectivity, harmonics suppression, stable antenna gain, and high polarization purity.

Multiband MIMO Antenna for GSM, DCS, and LTE Indoor Applications

A novel and compact planar multiband multiple-input-multiple-output (MIMO) antenna is presented. The proposed antenna is composed of two symmetrical radiating elements connected by neutralizing line to cancel the reactive coupling. The radiating element is designed for different frequencies operating in GSM 900 MHz, DCS 1800 MHz, LTE-E 2300 MHz, and LTE-D 2600 MHz, which consists of a folded monopole and a beveled rectangular metal patch. The presented antenna is fed by using 50-Ω coplanar waveguide (CPW) transmission lines. Four slits are etched into the ground plane for reducing the mutual coupling. The measured results show that the proposed antenna has good impedance matching, isolation, peak gain, and radiation patterns. The radiation efficiency and diversity gain (DG) in the servicing frequencies are pretty well. In the Ericsson indoor experiment, three kinds of antenna feed systems are discussed. The proposed antenna shows good performance in Long Term Evolution (LTE) reference signal receiving power (RSRP), download speed, and upload speed.

A Shared-Aperture Dual-Band Dual-Polarized Filtering-Antenna-Array With Improved Frequency Response

In this paper, a novel dual-band dual-polarized array antenna with low frequency ratio and integrated filtering characteristics is proposed. By employing a dual-mode stub-loaded resonator (SLR) to feed and tune with two patches, the two feed networks for each polarization can be combined, resulting in the reduction of the feed networks and the input ports. In addition, owing to the native dual resonant features of the SLR, the proposed antenna exhibits second-order filtering characteristics with improved bandwidth and out-of-band rejections. The antenna is synthesized and the design methodology is explained. The coupling coefficients between the SLR and the patches are investigated. To verify the design concept, a C-/X-band element and a

Compact Highly Integrated Planar Duplex Antenna for Wireless Communications

2 \times 2

Wideband Circularly Polarized Fabry-Perot Antenna [Antenna Applications Corner]

array are optimized and prototyped. Measured results agree well with the simulations, showing good performance in terms of bandwidth, filtering, harmonic suppression, and radiation at both bands. Such an integrated array design can be used to simplify the feed of a reflector antenna. To prove the concept, a paraboloid reflector fed by the proposed array is conceived and measured directivities of 24.6 dBi (24.7 dBi) and 28.6 dBi (29.2 dBi) for the X-polarization (Y-polarization) are obtained for the low- and high-band operations, respectively.

A Simple Low-Cost Shared-Aperture Dual-Band Dual-Polarized High-Gain Antenna for Synthetic Aperture Radars

This paper proposes a novel concept of an integrated duplex antenna for realizing a compact multifunction RF front end by integrating a duplexer and a dual-band patch antenna. First, an all-resonator-based duplexer is designed. It is composed of two sets of split-ring resonators as channel filters, which are joined by a dual-mode stub-loaded resonator as the junction resonator. Then, a novel dual-band patch antenna is achieved by coupling a patch with a hairpin resonator through a slot in the ground. Uniform radiation characteristics have been achieved across the two bands. Finally, the duplexer is integrated with the dual-band patch antenna to form a highly integrated duplex antenna by coupling the hairpin resonator to the junction resonator of the duplexer directly. In this process, the 50-Omega interface and matching network between them are removed, contributing to a compact footprint. The details of codesign approach have been discussed in this paper. Compared with the traditional cascaded duplexer and antennas, this paper is much more compact and integrated but with an improved frequency response. A prototype of an integrated duplex antenna at S-band is fabricated and measured, showing two operation channels of 2.52-2.65 GHz for transmitting and 2.82-2.94 GHz for receiving with an isolation of over 32 dB. The measured results agree well with the simulation results.

A Ka/X-band digital beamforming synthetic aperture radar for earth observation

A broadband and high-gain, circularly polarized Fabry-Perot (CPFP) antenna is presented in this article. This antenna employs a two-layer partially reflective surface (PRS) with positive reflective phase gradient, which can improve the 3-dB gain bandwidth of Fabry-Perot (FP) antennas effectively. To generate a circularly polarized (CP) wave, a wideband CP microstrip patch is designed to serve as the feeding source. To validate this concept, an antenna prototype at X band is fabricated. The measurement results show that this antenna achieves a 3-dB gain bandwidth of 28.3% from 8.8 to 11.7 GHz with the peak gain of 14.7 dBi. Within this frequency range, the axial ratio (AR) is below 3 dB and the reflection coefficient is lower than -10 dB.

Dual-band digital beamforming synthetic aperture radar for earth observation

This paper presents a novel shared-aperture dual-band dual-polarized (DBDP) high-gain antenna for potential applications in synthetic aperture radars (SARs). To reduce the complexity of SAR antennae, a DBDP high-gain antenna based on the concept of Fabry-Perot resonant cavity is designed. This antenna operates in both Cand X-bands with a frequency ratio of 1:1.8. To form two separate resonant cavities, two frequency selective surface layers are employed, leading to high flexibility in choosing desired frequencies for each band. The beam-scanning capability of this proposed antenna is also investigated, where a beam-scanning angle range of ±15° is achieved in two orthogonal polarizations. To verify this design concept, three passive antenna prototypes were designed, fabricated, and measured. One prototype has broadside radiation patterns, while the other two prototypes have frozen beam scanned to +15°. The measured results agree well with the simulated ones, showing that the high gain, high port isolation, and low cross-polarization levels are obtained in both the bands. Compared with the conventional high-gain DBDP SAR antennae, the proposed antenna has achieved a significant reduction in the complexity, mass, size, loss, and cost of the feed network.

A Triband Low-Profile High-Gain Planar Antenna Using Fabry–Perot Cavity

A Ka/X-band digital beamforming (DBF) spaceborne Synthetic Aperture Radar (SAR) is presented in this paper. To overcome the performance limitations of current SAR systems while reducing the cost, size, mass and power consumption, it employs a multi-static passive radar concept using DBF, highly integrated analogue and digital circuits and shared-aperture Ka/X band dual-polarization antennas. Compact modular architecture of the proposed system enables the realization of various configurations of spaceborne SAR missions. The radar concept is introduced, followed by some results of antennas, analogue and digital circuits as well as the MMIC technologies.