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A compact broadband circularly polarized elliptical slot antenna (CPESA) composed of two linked elliptical slots is presented. In order to realize the proposed CP antenna, two rectangular stubs are embedded in the feedline structure to excite two orthogonal vectors. By embedding two rectangular stubs in the feedline structure and removing of four rectangular slits from the ground plane, the return loss and the axial-ratio (AR) bandwidths are noticeably increased. The designed CPESA with the compact size of mm operates over the frequency band between 4.3-8 GHz (60%) for and exhibits a 40% (4.3-6.5 GHz) CP bandwidth. Throughout this letter, the design process of the proposed antenna is presented and discussed in detail. Index Terms-Axial ratio, C-band, elliptical slot antenna, microstrip antenna.1536-1225 © 2013 IEEE

A simple compact broadband circularly-polarised square slot antenna (CPSSA) fed by a coplanar waveguide is presented. A CP bandwidth larger than 38.2% can be attained simply by embedding two inverted-L grounded strips around two opposite corners whereas the impedance bandwidth can be greatly improved through the tuning stubs. The designed CPSSA antenna is 25 × 25 × 0.8 mm 3 , which is 56% smaller than previous CPSSA structures operating over the frequency band between 2.9 and 11.2 GHz for VSWR , 2.

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Summary This paper proposes a new adaptive clamp based on the hybrid operation of the interleaved two‐switch flyback micro‐inverter in one‐phase and two‐phase discontinuous conduction modes (DCM) depending on the output power of the PV panel. The proposed adaptive clamp controls the second switch of the two‐switch flyback structure based on the drain‐to‐source voltage spike of the flyback's main switch during the turn‐off process. Thus, in low‐voltage regions, a conventional flyback (single‐switch) operation is achieved with reduced switching, gate driving, and clamp diodes losses. Also, in the low output powers of the micro‐inverter, only one phase of the micro‐inverter operates to decrease the power loss associated with one phase. The theoretical analysis, simulation, and experimental results show the effectiveness of the proposed adaptive clamp and the phase control methods in improving the efficiency in all power ranges.

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This paper proposes a new soft switching high step-up DC-DC converter .The proposed converter is a kind of quadratic boost converter with the coupled inductor. The converter provides high step-up voltage gain with proper duty ratio and low switch voltage stress. Additionally, the stored energy in the leakage inductor of the coupled-inductor can be recycled to the output capacitor. In this converter an auxiliary circuit consist of one auxiliary switch and clamp capacitor is used for providing ZVS condition for all switches (switch and an auxiliary switch), and also the main switch is turned off under almost ZVS due to snubber capacitor. Also the proposed convertercontrolled by PWM signal, and so the implementation of control circuit is simple. To confirm the performance of the proposed converter, this converter is simulated by PSPICE.

In the unfolding-type interleaved two-switch flyback inverter (ILTFI) operating in discontinuous conduction mode (DCM), the hybrid control strategy combining the one-phase DCM and the two-phase DCM has a significant impact on improving the efficiency under all load conditions. In the situation where the marginal power of this control strategy is increased, the converter may enter CCM. Consequently, the converter cannot track the reference current and the output current quality is notably decreased. To tackle this issue, a novel hybrid control method is proposed which varies the switching frequency based on the output power. The proposed approach is immune to the loss analysis and power losses of the components. Hence, it is independent of components selection and their characteristics. In this case, the smooth transition between the one-phase and the two-phase operation modes is guaranteed without affecting the output power quality and the stability of the converter in DCM. The control complexity of the proposed scheme is low and the converter can be easily controlled in DCM. The performance of the flyback microinverter with the proposed hybrid control scheme is verified by the simulation and the experimental results together with the loss analysis.