In this paper, we investigate a new rectangular-fed printed open-slot antenna (POSA) with reflector, which has the advantages of improved radiation-pattern properties along with broad-bandwidth characteristics. The measured bandwidth of the proposed POSA with reflector is approximately 47.6% (Ϫ10 dB Ն S 11 ), thus, it can be used for PCS, DCS, and IMT-2000. But the measured bandwidth of the PCSA with reflector is approximately 46% (with VSWR Յ 2.0). The tilt angle at maximum gain is enhanced by using a modified POSA with reflector for practical applications. The radiation pattern null and distortion of the open-slot antenna exhibited better performances than those of the closed-slot antenna. The back-lobe level of the POSA with reflector also presented much better results than the PCSA with reflector. The proposed antenna obtained not only wider bandwidth but also better radiation patterns characteristics than the PCSA with reflector.ABSTRACT: This paper presents an active broadband-transmitting patch antenna, which works in the 1650 -2300-MHz band to provide GSM-1800 and UMTS services. An increase of the reflection bandwidth of the referenced passive antenna has been achieved due to the resistively equalized broadband-amplifying active antenna. An increase in equivalent isotropic radiated power (EIRP) of 11-12 dB compared to the passive antenna, with a ripple lower than Ϯ0.5 dB, has also been achieved.

The blackbody radiation spectrum is fundamental to any thermal emitter. However, by properly designing the emitter structure, a narrow bandwidth and high power infrared source can be achieved. This invention consists of a triple layer structure by sandwiching a dielectric SiO 2 layer between two Ag metal films on the Si substrate. The top Ag layer is perforated by periodic holes. When the device was heated, the background thermal radiation was suppressed by the bottom Ag whose emissivity is very low. The thermal radiation generated in the SiO 2 layer resonant between two metal films and the Ag/ SiO 2 and the Ag/air surface plasmon polaritons are induced and converted to light radiation. Strong resonance at Ag/ SiO 2 ͑1,0͒ degenerate modes results in the coherent light radiation at the wavelength associated with the dielectric constant of SiO 2 and the lattice constant of the perforated hole array. The ratio of the full width at half maximum to the peak wavelength is 0.114. This narrow bandwidth and high power infrared light source can be used to explore the biological response of cells and plants.

In this paper, we have developed an interpretation of transistor S-parameters by poles and zeros. The results from our proposed method agreed well with experimental data from GaAs FETs and Si MOSFET's. The concept of source-series feedback was employed to analyze a transistor circuit set up for the measurement of the S-parameters. Our method can describe the frequency responses of all transistor S-parameters very easily and the calculated S-parameters are scalable with device sizes. It was also found that the long-puzzled kink phenomenon of S-22 observed in a Smith chart can be explained by the poles and zeros of S-22

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A single-ended wideband downconversion Gilbert micromixer is demonstrated in this paper using 0.35-m SiGe BiCMOS technology. A transimpedance amplifier with resistive feedback is utilized in the IF stage while a broadband Marchand balun is employed to generate wideband differential local oscillator signals. The planar Marchand balun topology employed in this paper can generate truly balanced signals even in the presence of the lossy low-resistivity ( 10 cm) silicon substrate. A systematic approach to measure the frequency response of each individual stage in a Gilbert mixer is developed in this paper. This single-ended wideband mixer has the conversion gain of 15 dB, IP 1dB of 19 dBm, IIP 3 of 7 dBm, and the noise figure of 13 dB. The mixer works from 3.5 to 14.5 GHz. Index Terms-Downconverter, Marchand balun, micromixer, SiGe BiCMOS, silicon substrate, transimpedance amplifier (TIA), wideband.

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