Mutual coupling suppression of aperture coupled microstrip antenna array

A mutual coupling suppression method is proposed for microstrip antenna array by cutting four small semi-circle annular apertures on the metal plate. The structure of antenna array is composed of 2 × 2 four elements. The antenna consists of double layer dielectric, and it realizes circular polarization characteristics by cutting rectangular slot on circular patch in the direction of 45°, by using aperture coupling feeding and reverse feeding principle. There is 90＊ phase difference between adjacent antenna elements. Thus, it cuts off the coupling current field between the elements, suppresses the surface wave and reduces the mutual coupling by cutting four semi-circle annular apertures symmetrically on the metal plate. The simulation results show that after cutting four semi-circle annular apertures, the antenna array coupling coefficients decrease significantly, and the side and back lobe levels are suppressed effectively with the gain of antenna improved. So the proposed method is effective to suppress microstrip antenna array mutual coupling.

Novel Fractal DGS Based on MEMS and Its Application in Miniaturization of Microstrip Antenna Array

An uncommon fractal construction method is applied in the microwave element design. A novel fractal defected ground structure （DGS） based on micro electro-mechanical system （MEMS） is proposed. The size of this novel fractal DGS can achieve 86% size reduction compared with the conventional dumbbell type DGS. This novel fractal DGS is used in the miniaturization design of L-band microstrip antenna array. The simulation result shows that this novel fractal DGS can effectively reduce the mutual coupling between the antenna elements, so it is helpful to the miniaturization of microstrip array, namely the approximately same gain value can be achieved with the shorter distance between elements.

Design of MEMS C-Band Microstrip Antenna Array Based on High-Resistance Silicon for Intelligent Ammunition

In recent years, microstrip antennas have been more widely applied in satellite communications, mobile phones, unmanned aerial vehicle （UAV）, and weapons. A micro-electro-mechanical systems-based （MEMS-based） high-resistance silicon C-band microstrip antenna array has been designed for the intelligent ammunition. The center frequency is 4.5 GHz. A cavity has been designed in substrate to reduce the dielectric constant of silicon and high-resistance silicon has been used as the material of substrate to improve the gain of antenna. It is very easy to be manufactured by using MEMS technology because of the improved structure of the antenna. The results show that the gain of the antenna is 8 dB and voltage standing wave ratio （VSWR） is less than 2 by the analysis and simulation in high freauencv structure simulator （HFSS）.

Electromagnetic coupling reduction in dual-band microstrip antenna array using ultra-compact single-negative electric metamaterials for MIMO application

In this paper, an ultra-compact single negative（SNG） electric waveguided metamaterial（WG-MTM） is first investigated and used to reduce the mutual coupling in E ＆ H planes of a dual-band microstrip antenna array. The proposed SNG electric WG-MTM unit cell is designed by etching two different symmetrical spiral lines on the ground, and has two stopbands operating at 1.86 GHz and 2.40 GHz. The circuit size is very compact, which is only λ_0/33.6 ×λ_0/15.1（where λ_0 is the wavelength at 1.86 GHz in free space）. Taking advantage of the dual-stopband property of the proposed SNG electric WG-MTM, a dual-band microstrip antenna array operating at 1.86 GHz and 2.40 GHz with very low mutual coupling is designed by embedding a cross shaped array of the proposed SNG electric WG-MTM. The measured and simulated results of the designed dual-band antenna array are in good agreement with each other, indicating that the mutual coupling of the fabricated dual-band antenna array realizes 9.8/11.1 d B reductions in the H plane, 8.5/7.9 d B reductions in the E plane at1.86 GHz and 2.40 GHz, respectively. Besides, the distance of the antenna elements in the array is only 0.35 λ_0（where λ_0 is the wavelength at 1.86 GHz in free space）. The proposed strategy is used for the first time to reduce the mutual coupling in E ＆ H planes of the dual-band microstrip antenna array by using ultra-compact SNG electric WG-MTM.

Wideband dual-polarized slot-coupled microstrip array for synthetic aperture radar application

An 8 × 1-element wideband dual-polarized slot-coupled microstrip antenna array with high isolation and low crosspolarization in X-band is presented. The array antenna offers an impedance bandwidth （VSWR≤2） of 23% and 21% for dual polarization ports, respectively. The measured isolation between two polarization ports is better than 35 dB and the measured cross-polarization level below -25 dB in the main beam over the operation frequency band of 9.35 GHz to 9.75 GHz. This array is well suitable for X-band SAR （synthetic aperture radar） antenna apphcation.

Design of low-sidelobe circularly-polarized microstrip array for RFID readers

A low-sidelobe circularly-polarized(CP) microstrip patch array for 2.4 GHz radio frequency identification(RFID) readers is presented.The antenna array with a Chebyshev current distribution is composed of 6 microstrip elements.The CP operation is obtained by the quasi-square patch with difference in lengths of the two sides.The antenna has been investigated numerically and experimentally.Measured results show that the array has a Chebyshev pattern with the sidelobe level of-23 dB, the half-power beamwidth of 16° and an impedance bandwidth(S11≤-10 dB) of 130 MHz, which is suitable for RFID reader applications.

A New Dual Polarized Aperture-Coupled Printed Array for SAR Applications

This paper presents a new design of dual polarized aperture coupled printed antenna array. The finite difference time domain (FDTD) analysis of an aperture coupled microstrip element is performed, and the effects of antenna parameters on its characteristics are obtained to guide the design of the printed array. Then an 8×2 dual polarized array design in X band is introduced with configuration plots. In order to improve its isolation and cross polarization, an outphase displacement feeding technique is adopted in the feed network. Also, the round bends are used instead of conventional right angle bends so as to achieve better VSWR performance. Experimental results are presented, indicating the validity of the design. This dual polarized array can be applied as a sub array of spaceborne SAR systems.

An L-strip fed stacked patch antenna for maritime satellite communications

A practical antenna has been designed and developed for INMARSAT mobile satellite communications. The design uses low cost materials such as foam and copper foil to create a stacked microstrip antenna array. Several techniques were adopted to enhance the impedance bandwidth and axial ratio bandwidth. The final design parameters were optimized by EM simulation. Finally, the L-strip fed six-element stacked microstrip antenna array was constructed and tested. Simulated and measured results show that in the whole INMARSAT work band, the VSWR of the antenna is less than 1.6, its antenna gain is higher than 15dB and wide-angle axial ratio （AR） 3dB is more than 21°. The antenna has been successfully used with a HNS 9201 terminal.

Wideband Circularly Polarized Sequentially Rotated Microstrip Antenna Array with Sequential-Phase Feeding Network

A wideband 2×2 sequential-phase fed circularly polarized(CP)microstrip antenna array(MAA)with sequentially rotated elements is proposed.Firstly,the antenna element loaded with shorting pins is studied as compared to the traditional counterpart.Then,a feeding network is designed to be connected together in a sequential rotation manner,resulting in forming a four-port network to allow symmetrical positioning of CP microstrip patch elements.After that,straight strips are added to the feeding network in order to increase the distance and reduce coupling between array elements.They also play a role in improving the impedance matching of the array.Finally,the proposed antenna array is designed and simulated.The results are presented that its impedance bandwidth is about 36.3%at 24.1~34.8 GHz for|S_(11)|<10 dB and axial-ratio(AR)bandwidth is about 20.4%at 24.2~29.7 GHz for AR【3 dB.Besides,a peak gain of 11.1 dBic is simulated over the operating frequency range,which is significantly improved compared to the classic and existing works.