A novel pattern reconfigurable planar optically controlled Yagi–Uda antenna is proposed. The antenna comprises a director, a driven dipole, a reflector and the substrate. The two parasitic elements loaded with positive intrinsic negative (PIN) photodiodes in the middle, applied as manipulating switches, are capable of varying the radiation pattern by transforming their physical structures. A prototype of the proposed antenna along with PIN photodiodes was fabricated to verify the concept of optically controlled pattern reconfiguration. The simulated and experimental results indicate that the falsefalse|S11falsefalse| curves and radiation patterns of the proposed antenna in both the PIN switches' on and off state are similar; however, the direction of maximum radiation differs between these two states by 180∘. Good unidirectional radiation patterns with the front‐to‐back ratios of 12 and 8 dB are obtained. About 10 dB impedance bandwidth can reach 15% and the maximum gain is more than 6.3 dBi. This study proposes a three‐element equivalent current radiation model based on the current distribution from simulation, which can explain the directional radiation characteristics of the designed antenna well. This pattern reconfigurable antenna can be optically controlled remotely, reducing the effects of controlling network on the antenna radiator.

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This paper describes a printed wideband low profile omnidirectional dual-polarized antenna, which is a combination of vertical polarization (VP) and horizontal polarization (HP) elements. The VP element printed on a double-layered disk-shaped substrate is a modified monopole with loadings. The introduction of the material of the dielectric substrate can reduce the profile height in the polarized direction to 0.08λ L (the wavelength at the lowest frequency). And loading metallic cylindrical block and shorting-posts in the dielectric substrate to improve the bandwidth are realized by using metalvias. The HP element consists of a printed 8-element circular connected Vivaldi antenna array, and each element contains a director in the slot for the improvement of radiation pattern's out-of-roundness. Both the simulated and measured results indicate that operating bands of 2.2-4.52 GHz for VP and 2.4-3.8 GHz for HP. This proposed antenna has good isolation and omnidirectional patterns with the out-of-roundness less than 2.5 dB in the azimuth plane for both VP and HP, and it can be applied in mobile communication systems.

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A high isolation broadband dual-polarized omnidirectional antenna comprising two low profile orthogonally polarized omnidirectional radiating elements is presented. A modified monopole using loadings to broaden impedance bandwidth is applied to vertical polarization (VP), while four printed concentrically arranged Yagi-Uda-like antennas are employed for horizontal polarization (HP). Both the simulated and measured results indicate that the operating bands of the proposed antenna with its reflection coefficient less than −10 dB are 1.48 to 3.16 GHz for VP and 1.69 to 2.7 GHz for HP. A good port isolation larger than 40 dB and omnidirectional patterns with the out-of-roundness less than 2 dB in horizontal plane are obtained. This paper explains the radiation mechanism by investigating the simulated surface current distributions for VP element and establishing a radiation model for HP element, and also analyzes the performance of the proposed antenna. This antenna design can be applied to 4G (LTE) communication system.