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A planar dual-band dual-mode antenna with omni-/unidirectional radiation is proposed for operating 2.45/5.8 GHz bands. The lower-band antenna consists of 4 modified quarter-mode substrate-integrated waveugide (QMSIW) elements, which are excited in-phase and with same magnitude to obtain vertically polarized omni-directional radiation. The upper-band antenna is based on a four-port square patch with differential feed to achieve highly-isolated dual-polarization with broadside radiation. In addition, the square patch is loaded with four overlapped-corner-mushroom structures to broaden the upper bandwidth. The final design with overall size of of 90 90 3.66 mm (0.735 0.735 0.03 at 2.45 GHz) was fabricated and measured. Measurements show a 10-dB return loss bandwidth of 160/400 MHz and a gain of 3.4/8.5 dBi at 2.45/5.8 GHz bands, respectively. Furthermore, the antenna prototype demonstrates an isolation of more than 30 dB among all ports. Especially, the isolation among the two ports of the upper-band elements is better than 40 dB.

CubeSat structure satellites have limited communication ability as a result of limited power and size, as well as low cost transceivers. The communication between CubeSat and the Earth station therefore faces a lot of risks such as impairing transceiver performance and degrading mission data throughput. In this paper, a design of S-band transceiver for telemetry, tracking and control (TT&C) is presented for use onboard CubeSat satellites. The transceiver can provide a measured 96 Kbps of data rate with maximum output power of 39.3 dBm (8.5 W) and an overall volume of 87.4 93.4 20 mm3 with total mass of 252 grams including aluminum housing.

Effect of curvature of antipodal structure on Vivaldi antennas is presented in this paper. The results indicate that inner curvature has a significant impact on the return loss S11. In addition, a new estimation of lower frequency limit is shown. Based on our design, an antipodal Vivaldi antenna has been fabricated and verified its properties through measurements.

In this paper, a small metamaterial antenna with high efficiency is presented. The antenna is proposed for 2.4 GHz Wireless Local Area Network (WLAN) application. The metamaterial resonant antenna is designed with a mushroom structure which based on the zeroth order resonant characteristic of a composite right/left-handed transmission line (CRLH TL). The antenna is designed on the low-cost FR4 substrate with dielectric constant er = 4.4 and tan δ= 0.02. The antenna is simulated and optimized by HFSS 14. The simulation results show that antenna has small size and a good bandwidth with range from 2.40-2.48 GHz for return loss S11 less than -10 dB. The proposed antenna offers high efficiency 72-75% in operation bandwidth. The overall dimension of the antenna is 20.0×22.0×1.6 mm3 including the antenna substrate.

In the last decades several population-based heuristic search techniques have been developed for the optimization of combinatorial electromagnetic problems, all of them are modeled on the concepts of natural selection and evolution e.g. Genetic Algorithm (GA), Particle Swarm Optimization (PSO). Moreover, vast variations of original methods can be found in the literature. In this paper, with the intent of examine the reliability and convergence speed of those methods, some comparisons in optimizing a dual-ring microstrip antenna will be presented. Preliminary results are here presented to demonstrate the analysis of robustness and effectiveness of optimization tools.

Nowadays the design of complex real electrical, electronic or electromagnetic systems may effectively exploit the characteristics of population based global optimizers. One of the main drawbacks of the adoption of these optimizers in the design of a real system is the difficulty in the introduction, in the optimized design algorithm, of all the heuristic knowledge already available in the field. In order to overcome this problem compact genetic algorithms, classified as estimation of distribution algorithm, could be very effective, since they apply and manipulate a suitable probability vector to represent the distribution of good solutions. Unfortunately, their straightforward implementations usually lack of exploration, and they are easily trapped in local maxima. In order to overcome even this drawback and to develop a compact genetic algorithm with both the required exploitation, of the heuristic knowledge, and the exploration, for avoiding local maxima, in this paper a modified cGA is proposed by implementing more probability vectors and adding a suitable learning scheme to the traditional one in order to ensure the effectiveness of the algorithm. The here proposed new algorithm has been tested on some mathematical test functions and on a typical EM design problem, a microwave microstrip filter synthesis.

The objective of this work is the design of a 32×32 element X-band reflectarray, in which the re-radiated elements have no conventional shape and enough degrees of freedom to compensate both the spatial and frequency phase variation of the re-radiated field. In particular, here we focus on a re-radiating element consisting in two concentric square rings in which two different and quite independent geometric parameters are varied.