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A novel gallium nitride-based high electron mobility transistor power amplifier design is presented that uses an artificial neural network modeling technique.

Due to the properties of inverse refraction, the metamaterials can focus the incident wave and can be used as a lens for high directive antennas. For this purpose, in this study, initially, a metamaterial unit cell is designed to exhibit metamaterial feature at 12 GHz and converted into a periodic layer. The reference antenna and the proposed metamaterial layers are simulated and fabricated. It is observed that the directivity of the reference antenna is increased by 2.74 dB with one layer of the proposed metalayer according to the measurement results. Finally, a double lens layer is used and an increase of 4.08 dB is observed. In the literature, the dimensions of metalayers, that is, used to achieve directivity enhancement, are larger than the patch size, but in this study we achieve a significant improvement with metalayers that have almost the same dimensions as the patch. However, the proposed antenna system is more effective than Ku-band antennas in the literature due to its high directivity compared to similar ones. [ABSTRACT FROM AUTHOR]

This paper proposes improving the directivity of microstrip patch antennas (MPAs) by using metamaterials. Four different metamaterial types are used as a at lens in front of the MPA, respectively, which are tuned to 12 GHz (Ku-band) resonance frequency. Thus, it can be decided which metamaterial is more proper for antenna directivity enhancement at this band. One additional new metamaterial structure is proposed in this paper, which is called a Euro-shaped resonator, and other metamaterials used are the triangular split ring resonator, symmetrical ring structure, and split ring resonator. The permeability and permittivity of metamaterials are extracted from the S parameters by using a robust method. Microwave Studio by Computer Simulation Technology is used for modeling and simulation. The MPA and metamaterials are fabricated, and measurements are performed in the Yíldíz Technical University RF and Microwave Laboratory. It is observed that measured results are in close agreement with the computer simulations. [ABSTRACT FROM AUTHOR]

A wideband I-type rectangular waveguide rotary joint (RJ) is designed, simulated and built. It has an excellent performance over the whole Ku Band (10.7 - 14.5 GHz) where the return loss is less than -23 dB at its highest and the insertion loss is below 0.4 dB. The rotary joint is specifically designed for satellite news gathering (SNG) vehicles providing elevation and azimuthal movement to the antenna and matching polarization when it is needed at the feed. It can also be used in other high power microwave applications, where rotation ability of the antenna is a must during the transmission such as radars. [ABSTRACT FROM AUTHOR]

Herein, a new methodology using a 3D Electro-magnetic (EM) simulator-based Support Vector Regression Machine (SVRM) models of base elements is presented for band-pass filter (BPF) design. SVRM models of elements, which are as fast as analytical equations and as accurate as a 3D EM simulator, are employed in a simple and efficient Cuckoo Search Algorithm (CSA) to optimize an ultrawideband (UWB) microstrip BPF. CSA performance is verified by comparing it with other Meta-Heuristics such as Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). As an example of the proposed design methodology, an UWB BPF that operates between the frequencies of 3.1GHz and 10.6 GHz is designed, fabricated and measured. The simulation and measurement results indicate in conclusion the superior performance of this optimization methodology in terms of improved filter response characteristics like return loss, insertion loss, harmonic suppression and group delay. [ABSTRACT FROM AUTHOR]