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Fuel cells are used as a power generator in distributed generation and aircrafts applications. This paper proposes a new high step-up DC-DC converter with zero-voltage switching (ZVS) of switches and zero current switching (ZCS) of diodes, to be used as fuel cell's power conditioner. To have a ripple free input current, a coupled inductor can be used at the input side of the converter. The voltage gain of the converter is calculated and required conditions for soft switching have been presented. The voltage stress of elements of the proposed converter is discussed, the efficiency of converter is derived and finally experimental results have been used to validate the properties of the converter.

A broadband dual-polarized omnidirectional antenna is presented. The proposed antenna consists of two parts, an asymmetric biconical antenna and a cylindrical multilayer polarizer. To have an almost perfect omnidirectional radiation pattern in the horizontal plane and the main radiating beam position at around h575 8 , in the elevation plane, the asymmetric biconical antenna is used. Moreover, to provide dual polarization performance over the 2-18 GHz operational bandwidth, a multilayer polarizer is designed and optimized. Numerous simulations via Ansoft HFSS and CST microwave Studio CAD tools have been made to optimize the radiation pattern, gain, polarization, and the reflection coefficient of the antenna. Simulation results show that the radiation characteristics of the proposed antenna are extremely sensitive to the configuration and dimensional parameters of the multilayer polarizer. The designed antenna was fabricated with high mechanical accuracy and measured. Satisfactory agreement of computer simulations and experimental results was obtained. The main feature that distinguishes this antenna from the previous designs is the ability to provide the omnidirectional radiation pattern with small ripples, dual polarizations performance, and the wide bandwidth simultaneously. Based on these characteristics, the proposed antenna can be useful for broadband communication applications. V C 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:591-600, 2015.