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A simple formula based on transmission line modeling (TLM) is proposed to determine the VSWR < 2 impedance bandwidth upper frequency limit for a staircase-profile planar monopole antenna. After a brief description of TLM analogy for planar monopoles, the formula is derived from a theoretical exposition. Accordingly, four prototypes are designed, implemented and measured in such a way that they are required to cover direct sequence ultrawideband (DS-UWB) first band (up to 4.85 GHz), UWB (up to 10.6 GHz) and possible future broadband systems (e.g., up to 15 and 21.4 GHz). The formula predicts this limit with a maximum error of 7.4% in the prototypes studied. The height of the antennas is chosen so that they help to filter WLAN 5 GHz band on the H-plane. This condition determines the lower impedance bandwidth limit (1.3 GHz for all of them). The resulting improvement on antenna system transfer functions (ASTF) is also discussed. Index Terms--Broadband antennas, monopole antennas, transfer functions, transmission line modeling (TLM), ultrawideband (UWB) antennas.

This paper presents a new methodology for measuring integrated transformers. It gives a description of the transformer and its specifications and develops a measurement system. It also presents different transformer geometries and transformer terminal combinations. After the theoretical exposition of the measurement system, a differential-differential integrated transformer and a single-single integrated transformer are measured using this system in order to validate the methodology proposed. In the state-of-the-art, there is no fixed methodology for measuring the coupling factor k of a transformer. This paper presents a new methodology for obtaining this figure-of-merit systematically. As a result of this measurement, this paper presents the values obtained and corroborates the measurement system. Thus, this paper presents and explains a new systematic method for measuring transformers. Index Terms--Coupling factor, integrated transformer, measurement system, methodology.

From the current distribution on planar monopoles, transmission line modeling is applied to study this kind of antennas. Some reported techniques for broadband monopoles are approached by using this model from a qualitatively point of view. Conclusions are derived that help to match the monopoles over an ultrawide bandwidth regardless of whether they are folded or not. Folded configurations are obtained in order to provide solutions to specific designs and improve radiation pattern maintaining the planar monopole broadband behavior. Three compact folded prototypes with greater than 1:38 bandwidth are implemented and tested. Pulse distortion is also discussed for this type of applications. Index Terms--Folded-plate monopoles, impedance bandwidth, planar monopoles, transmission line modeling, ultrawideband (UWB) antennas.

One of the most restrictive linearity constraints to RF transmitter nonlinearity is the unwanted emission immediately outside the channel bandwidth, mostly known as adjacent channel leakage ratio (ACLR). In this paper, novel architecture design rules are presented for ACLR-level measurement in feedforward adaptive amplifiers. Both main and distortion signal power levels are obtained without any masquerading effect and with minimum component utilization. A prototype implementation is introduced to validate the proposed design rules, and a commercial spectrum analyzer is used for accuracy checking. Finally, the thermal stability has been tested for the -20 °C to 70 °C range. [ABSTRACT FROM AUTHOR]

A method using 180° hybrid coupler and vector network analyser to measure the radio frequency identification tag antenna impedance is presented. The impedance of a prototype antenna is measured by different experimental methods and compared with simulation results. The comparison results show that the proposed method has a good accuracy and it is more convenient. [ABSTRACT FROM AUTHOR]