The high-frequency performance of the reflector antennas is mainly limited by the surface. It has been shown that distortions on different regions of the reflector surface can have different effects on the radiation performance. In other words, degradation of the radiation pattern due to the presence of surface distortions is sensitive to the location and behavior of the surface distortion prof...

An optimal design of a linear antenna array is presented. The antenna array is optimized using a particle swarm optimization based method in order to produce a radiation pattern that has the minimum possible side lobe level and the maximum possible gain at the desired direction. The method has been applied to collinear wire-dipole arrays and seems to be suitable for improving the radiation patt...

We observe the angular radiation pattern of single carbon nanotubes' photoluminescence in the back focal plane of a microscope objective and show that the emitting nanotube can be described by a single in-plane point dipole. The near-field interaction between a nanotube and an optical antenna modifies the radiation pattern that is now dominated by the antenna characteristics. We quantify the an...

A printed slot antenna fed by a microstrip line with a diamond-shaped tuning stub for bandwidth enhancement is proposed and experimentally validated. Impedance bandwidth, radiation pattern, and gain characteristics of the proposed antenna are investigated. The simulated results show that the impedance matching of the proposed rotated slot antenna is greatly affected by the dimension of the slot...

A Planar antenna with Microstrip feed Sierpinski carpet fractal geometry for multiband applications is presented. The multiband behavior is analyzed through two fractal iterations. Self similarity property of fractal technology is applied in the antenna design to reduce the physical size, increase bandwidth and gain. The proposed antenna covers multi bands such as 1.8/5.59/5.78/6.4/6.63/7.84 GH...

In this manuscript, higher-order Orbital Angular Momentum (OAM) modes and parameters affecting vortex in the radiation pattern have been studied. A uniform circular array resonating at 10 GHz frequency is formed using eight identical rectangular patch antennas. Three uniform circular arrays are analyzed, simulated, and fabricated for OAM modes 0, +1, and -1 respectively. The higher-order OAM mo...

Recently, many works have considered a physical properly of antenna in MIMO channel models, such as radiation pattern effective for MIMO system. However, effect of antenna for MIMO with different algorithms is required and also with different environments of signal behavior at each end of the link. Thus, a traditional antenna such as Omni-directional antenna generally is used to design MIMO sys...

We experimentally demonstrate the control of the spontaneous emission rate and the radiation pattern of colloidal quantum dots deterministically positioned in a plasmonic patch antenna. The antenna consists of a thin gold microdisk separated from a planar gold layer by a few tens of nanometers thick dielectric layer. The emitters are shown to radiate through the entire patch antenna in a highly...

A new shaped circularly polarized dielectric resonator antenna (CP DRA) is studied with branch-line coupler and log-periodic balun for the GPS application. Since the coupler and balun are located under the DRA, it does not increase the footprint of the antenna, as a result the system is very compact. Two configurations are considered in this paper. In the first configuration, an external 50Ω lo...