We describe a novel method for measuring the unconstrained flatness error of thin, plane-parallel precision optics. Test parts are floated on high-density aqueous metatungstate solutions while measuring the flatness error with an interferometer. The support of the flat optics by the uniform hydrostatic pressure at the submerged face of the flat optic eliminates flatness errors caused by mountin...

In angle calibrations the uncertainty contributions of the autocollimator and index table are easily estimated as these uncertainties are well documented, but it is more difficult to determine the uncertainties associated with flatness deviations, eccentricity and pyramidal errors of the measuring faces. Deviations in the flatness of angle surfaces have been held responsible for the lack of agr...

This work describes the comparison of the amplification characteristics (gain) and the Noise figure (NF) of the Thulium and Erbium in three different host materials which the Yttria Alumina-Silica glass, Fluoride and Tellurite fiber glass. The gain using these host materials covers the range 1.45-1.65 μm. Thulium doped fiber amplifier (TDFAs) operated in the region of wavelength (1480-1510 nm) ...

A symmetric Power Amplifier with an optimized impedance quarter wave transmission line is presented using a thermally enhanced high Power LDMOS FET i.e. a 140W Infineon PTFC261402 device. This implementation is realized in the operating frequency of LTE Band41 (2.496GHz-2.69GHz) applicable for LTE base stations. This design achieves a high efficiency that persists for an output power back off r...

in this paper, an intelligent control strategy based on combination of the “flatness based control technique” and the “perturbation and observation (p&o;) mppt algorithm” is developed and investigated to control a hybrid electric energy source (heps). this ehps is composed of a fuel cell system (fc) and a solar panel (sp), as the main source and a supercapacitor bank (sc), as the auxiliary sour...

We demonstrate supercontinuum generation in a PCF pumped by a gain-switched high-power continuous wave (CW) fiber laser. The pulses generated by gain-switching have a peak power of more than 700 W, a duration around 200 ns, and a repetition rate of 200 kHz giving a high average power of almost 30 W. By coupling such a pulse train into a commercial nonlinear photonic crystal fiber, a supercontin...

In this paper, a D-band power amplifier (PA) based on 0.5-μm InP DHBT is presented. Wilkinson combiners with broadband stepped-impedance matching are used, and the eight-way PA is designed for wideband power performance. As input power is fixed at 3 dBm, the PA exhibits a saturated output power of 16.8 dBm and 7.9% PAE at 150 GHz with >45-GHz 3-dB power bandwidth from 125 GHz to 170 GHz. Meanwh...

Our paper, ‘Human Geography without Scale’ (Marston et al. 2005), is developed in two parts: a critique that is immanent to scale, where we show that, even on the grounds of contemporary spatial theory, the concept is deficient; and a critique that is extrinsic to those grounds, where we make a contribution to an alternative ontology that does not rely on the transcendental abstraction of scale...

A novel approach to broadband log-periodic antenna design is presented, where some of the most powerful evolutionary algorithms (EAs) are applied and compared for the optimal design of wire log-periodic dipole arrays (LPDA) using NEC (Numerical Electromagnetics Code). The target is to achieve an optimal antenna design with respect to maximum gain, gain flatness, Front to Rear ratio (F/R) and SW...

This paper describes the design of an X-band balanced low noise amplifier (LNA) using an available HJFET device. The balanced LNA consists of a pair of electrically similar transistors whose input and output signals are divided or combined by 3 dB two-stage Wilkinson power dividers. The proposed balanced LNA is fabricated and measured. The measured results show that the noise figure is 1.30 dB ...