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Several wideband millimeter-wave dielectric reflectarray antennas are discussed in this paper. Different phase distributions are realized by changing the shape or material of the array element. Three dielectric reflectarray of 20×20 elements operating at 100GHz are compared. The 1dB gain bandwidths of the dielectric reflectarray are larger than 10% and up to 40%. As compared to the microstrip reflectarray,...
A novel terahertz double-layered dielectric reflectarray antenna is proposed. A ground and two dielectric blocks constitute the array element. The phase tuning can be obtained by adjusting the dimensions of the blocks. The proposed reflectarray of 20×20 elements operates at 100GHz. The HFSS simulation results show that the maximum gain is 25.4dBi with the direction of 25° and the 1-dB gain bandwidth...
Bank to Turn (BTT) missile is a nonlinear control system with severe coupling between its three channels. Therefore, independent control system design method for three channels cannot be employed directly for BTT autopilot. In this paper, the linearized mathematical model for BTT missile is established first. Then the coupling factors between three channels are removed using coordinated control theory...
Gain fluctuation in a microwave photonic phase shifter based on Brillouin slow and fast light is theoretically and experimentally analyzed. The results show that, in order to reduce the gain fluctuation, it is necessary to increase the vestige sideband suppression ratio of the single-sideband modulation. Additionally, the input power of the optical single-sideband modulation signal should be set at...
Antipodal curvedly tapered slot antennas (ACTSAs) with different slot profiles are investigated to achieve the optimum circular polarization performance. The profiles of the tapered slots can be determined by different curves, such as linear, exponential, and logarithmic curves. Therefore, the corresponding waveguide-fed circularly polarized (CP) antipodal linear, exponential, exponential-logarithmic...
A multi-layer corrugated circular-aperture terahertz (THz) horn antenna based on MEMS (Micro-electromechanical System) technology is presented in this paper. The proposed antenna reveals bandwidth for return loss below −13 dB from 470 GHz to 530 GHz. The radiation pattern exhibits symmetric beam and very low cross-polarization. The peak gain varies from 18.9 dBi to 20.2 dBi within the frequency band...
As the simple structure, Monopole antenna has been widely used in various communication systems. However, the narrow bandwidth of the monopole antenna always restricted their applications. The article presents a method to improve the bandwidth of the monopole antenna with graded multi-layer metal slabs. The measured results of the proposed monopole antenna show wide bandwidth between 2.9GHz and 3...
A waveguide-fed circularly polarized corrugated antipodal tapered slot antenna (ATSA) working in the Ka band (26.5∼40 GHz) is proposed in this paper. The exponential tapering shape is adopted to maintain the consistency of the antenna's beam-width. In addition, the corrugation structure along the edges of ATSA is particularly designed to improve the axial ratio and cross polarization properties of...
This paper presents a low-power and small-size variable gain amplifier (VGA) which consumes only 1.1mW and occupies only 132um × 59um in 0.18-um CMOS technology. The proposed circuit is implemented by Gilbert cells and an exponential function circuit for the dB linearity of the gain voltage. The gain of the VGA can be varied linearly in dB from −10dB to 50dB with respect to a control voltage from...
This paper presents an all CMOS decibel-linear Automatic Gain Control (AGC). This AGC achieves large dynamic range with low power consumption. By applying digital switches to change exponential approximation function, four dynamic ranges (62, 50, 33, 26 dB) are realized. This AGC is implemented in TSMC 0.18-µm CMOS RF process. Measurement results show that this AGC achieves 60 dB linear range with...
An ultra-wideband low cross-polarization printed log-periodic dipole antenna (LPDA) is systematically investigated. The properties of the proposed antenna have been Simulated and optimized with electromagnetic simulation software FEKO 6.2. The antenna possess the operating bandwidth from 0.8GHz to 7.2GHz with the return loss less than −10dB, the cross-polarization and side lobe level are less than...
This paper presents a terahertz high-gain antenna which has a certain beam scanning capability and the antenna also has an offset Cassegrain reflector structure. Beam scanning method is analyzed by the theory of quasi-optics. Moreover, we elaborate critical analysis algorithm of the antenna. Simulation results show that, in the initial position, the gain of the antenna is 44.98dB, the half-power beam...
Relay enhanced cellular (REC) system and orthogonal frequency division multiple access (OFDMA) technology are regarded as the key features of 4G communication systems. How to utilize resource wisely in OFDMA-based REC systems is an important and challenging research topic. This paper reviews the major issues in designing radio resource management (RRM) algorithms for REC systems. A new resource allocation...
In this paper, the problem of static state feedback H∞ control with various regionl stability constraints for the closed-loop system is considered. A general framework for solving this problem is established using the Lagrange multiplier method in conjunction with the generalized Lyapunov theory and the Riccati equation based H∞ optimization characterization. Necessary conditions are given for the...
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