This paper presents the design of a wideband microstrip patch antenna for LTE-A. The bandwidth of the conventional patch is enlarged by using etched slots at the antenna patch. The designed antenna has been fabricated by using thin film and photolithographic technique and has been measured by using the Vector Network Analyzer. The simulated and measured results were found to have good match with each other. Then, by using the designed single element antenna, a four-element MIMO antenna system has been built employing orthogonal polarization diversity. Isolation between the microstrip elements is increased by placing metal structure between antenna elements. For more isolation between antenna elements, Slotted Ground Plane SGP is utilized. It is found, by using commercial software CST Microwave Studio and measurement, that the designed planar MIMO antenna system has sufficiently high return loss and low mutual coupling at the required bandwidth of 70 MHz. It is found also that the developed antenna system meets the requirements for LTE-Advanced (2500-2570 MHz) band "CA-B7" as of today"s standard based on 36.101 Table 5.5-1 (March 2012) .
A compact two element MIMO (Multiple Input Multiple Output) system is proposed using H-shape antenna with parasitic elements employing polarization diversity. The proposed MIMO system offers improved bandwidth; return loss, separation between antenna elements and isolation characteristics. The system resonates at 2.36GHz and 5.2 GHz frequencies with VSWR ≥2, which can be used for 4G & WiMAX applications. The simulation results of return loss, mutual coupling, correlation coefficient and gain are presented. The design is performed by using Ready-made software package Zeland-IE3D. The antennas are fabricated using thin film and photolithographic technique and measured using the Vector Network Analyzer. Good agreements were found between the simulated and measured results.
Two novel Defected Ground Structures (DGS) were first proposed, which have better results than that of the dumbbell (published shape). Using the general model of DGS, its equivalent parameters were extracted. The two new proposed shapes of DGS were then used to design a novel compact spider microstrip antenna to minimize its area. The size of the developed antenna was reduced to about 90.5% of that of the conventional one. This antenna with two different novel shapes of DGS was designed and simulated by using the ready-made software package Zeland-IE3D. Finally, it was fabricated by using thin film and photolithographic technique and measured by using vector network analyzer. Good agreements were found between the simulated and measured results.
Abstract-In this paper, a new technique is proposed for field effect transistor (FET) small-signal modeling using neural networks. This technique is based on the combination of the Mel frequency cepstral coefficients (MFCCs) and discrete sine transform (DST) of the inputs to the neural networks. The input data sets to traditional neural systems for FET small-signal modeling are the scattering parameters and corresponding frequencies in a certain band, and the outputs are the circuit elements. In the proposed approach, these data sets are considered as forming random signals. The MFCCs of the random signals are used to generate a small number of features characterizing the signals. In addition, other MFCCs vectors are calculated from the DST of the random signals and appended to the MFCCs vectors calculated from the signals. The new feature vectors are used to train the neural networks. The objective of using these new vectors is to characterize the random input sequences with much more features to be robust against measurement errors. There are two benefits for this approach: a reduction in the number of neural networks inputs and hence a faster convergence of the neural training algorithm and robustness against measurement errors in the testing phase. Experimental results show that the proposed technique is less sensitive to measurement errors than using the actual measured scattering parameters.
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