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The electromagnetic (EM) coupling effects of microstrip antennas have become increasingly prominent in complicated electric systems. In this article, a hybrid method is proposed based on the combination of cavity eigenmode theory and BLT equation. First, the internal electric field generated by the transmission lines inside the resonant cavity is obtained via cavity eigenmode theory. Then, the coupling mechanism between the electric field and microstrip antenna is established through radiation coupling interference. On this basis, the BLT equation and numerical integration method are applied to determine the induced voltage at the target microstrip antenna. Eventually, the proposed approach is validated by a full-wave simulation method and the impact of the microstrip antenna parameters on the coupling interference is discussed. This article provides an analytical method for calculating the coupling of a microstrip antenna. Compared with numerical simulation, this method has certain potential advantages in solving closed electrically large objects. Furthermore, duplicate modeling can be avoided in the same type of scenario. [ABSTRACT FROM AUTHOR]

A novel wideband and compact water antenna with optically transparent characteristic is presented in this communication. This antenna mainly consists of a fan-shaped cylindrical radiator, a top disk, a cylindrical base, and a water reflector. Based on two resonant modes, this antenna can achieve wideband characteristic. Meanwhile, when combined with fan-shaped radiator and top disk loading, the overall dimensions can be greatly reduced without compromising impedance matching. The ground made of distilled water is used for full transparency. The proposed antenna covers frequency range from 1.16 to 2.79 GHz for $S_{11} < -10$ dB. As far as we know, the proposed antenna shows the widest relative bandwidth (82.5%) in the field of transparent antennas, without sacrificing size and radiation performance. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]

A dual-polarized magnetically coupled patch antenna array with high isolation is presented in this paper. The proposed ${{1}} \times {{2}}$ antenna array is composed of two square patches printed on the horizontal substrate, two pairs of feeding structures printed on the two vertical substrates, a pair of metal cavities and a novel artificial periodic structures (APS) composed of metal strips etched vertically on the ground plane. Each feeding structure is orthogonally mounted and excites the square patch magnetically. The feeding structure comprises a metal loop or quasi-loop printed on one side of the vertical substrate and an open-ended transmission line printed on the other side. The metal cavities and APS can further improve the port isolation between array elements. The simulation and measurement results of single antenna element demonstrate its extremely high port isolation (better than 45 dB over 20% impendence bandwidth for {\text{VSWR}} < \,1.5). For the array, numerical and experimental results show that the port isolation with same polarization can be improved to over 45 dB across the frequency band of 2.5–2.7 GHz. The proposed antenna array achieves wide bandwidth with very high isolation, high gain, and high radiation efficiency. [ABSTRACT FROM AUTHOR]

A compact dual-polarized printed dipole antenna for wideband base station applications is presented in this communication. The proposed dipole antenna is etched on three assembled substrates. Four horizontal triangular patches are introduced to form two dipoles in two orthogonal polarizations. Two integrated baluns connected with 50 \Omega SMA launchers are used to excite the dipole antenna. The proposed dipole antenna achieves a more compact size than many reported wideband printed dipole and magneto-electric dipole antennas. Both simulated and measured results show that the proposed antenna has a port isolation higher than 35 dB over 52% impendence bandwidth (VSWR< 1.5). Moreover, stable radiation pattern with a peak gain of 7 dBi – 8.6 dBi is obtained within the operating band. The proposed dipole antenna is suitable as an array element and can be used for wideband base station antennas in the next generation IMT-advanced communications. [ABSTRACT FROM PUBLISHER]