Optimal Design of Broadband Loaded Wire Antennas Based on Genetic Algorithm

This paper, using the frequency bandwidth, where both the gain and the VSWR (Voltage Standing Wave Ratio) of a monopole can satisfy the design requirement, as object function, mainly describes the process, in which the load locations, the matching network topology and their component values are optimized by the AGA (Adaptive Genetic Algorithm), to achieve a gain more than -2 dB in horizontal direction and a VSWR less than 3 in bandwidth as wide as possible. Moreover the design results are presented for monopoles with two concentrated loadings. It shows that the AGA is an effective method for designing wideband antennas.

Ultra broadband flat dispersion tailoring on reversed-rib chalcogenide glass waveguide

In this paper,we introduce a horizontal slot in the reversed-rib chalcogenide glass waveguide to tailor its dispersion characteristics.The waveguide exhibits a flat and low dispersion over a wavelength range of 1080 nm,in which the dispersion fluctuates between-10.6 ps·nm-1·km-1 and ＋11.14 ps·nm-1·km-1.The dispersion tailoring effect is due to the mode field transfer from the reversed-rib waveguide to the slot with the increase of wavelength,which results in the extension of the low dispersion band.Moreover,the nonlinear coefficient and the phase-matching condition of the fourwave mixing process in this waveguide are studied,showing that the waveguide has great potential in nonlinear optical applications over a wide wavelength range.

A novel broadband power amplifier in SiGe HBT technology

A novel broadband power amplifier fabricated in 0.13 m SiGe HBT technology is realized.The pseudo-differential structure is proposed to avoid the influence of the bonding wire due to the AC virtual ground created at the common emitter node.A compensated matching technique is adopted in interstage matching to expand bandwidth.A multi-stage broadband matching technique is used in an input/output matching network to offer broadband impedance matching,which ensures maximum power transfer.An adaptive bias circuit could improve linearity and efficiency in wide output power level.With 2.5 V power supply,the measured results achieve 96% 3-dB bandwidth（517-1470 MHz）,27.2 dB power gain,26.9 dBm maximum output power,19.7 dBm output 1 dB compression point,and 26.7% power added efficiency.

Designing broadband fiber optic parametric amplifier based on near-zero single ZDW PCF with ultra-flat nature

We propose a broadband fiber optic parametric amplifier（FOPA） based on a near-zero ultra-flat dispersion profile with a single zero-dispersion wavelength（ZDW） by using a selective liquid infiltration technique.The amplifier gain and bandwidth is investigated for a variety of fiber lengths, pump power, and operating wavelengths. It is observed that sufficient peak gains and broader bandwidths can be achieved with a small negative anomalous dispersion（β2≤ 0） and a positive value of the 4th-order dispersion parameter（t β4）around the pump. We can optimize an FOPA with a bandwidth of more than 220 nm around the communications wavelength.

A broadband helical loaded square cavity back antenna array

In this paper, a fundamental advancement of the basic helix design which expands to array having good bandwidth is proposed. The helix is inserted in a cavity. The result is a new antenna design that offers the performance characteristics and advantages of the conven-tional helix but in a much more compact physical size envelope. A 4-element rectangular helical array has been designed. For miniaturization and impedance matching, the helical wire is replaced by a rectangular cross sectioned strip. It has been observed that when the helix is inserted in a cavity, it behaves differently from a normal helical antenna. The effects of the cavity on the number of turns, the impedance of total antenna, and the reflection coefficient have been analyzed. The array is designed for 2.4 GHz. The return loss obtained is less than - 10 dB and the bandwidth is more than 1.3 GHz for the array.