Frequency-selectable dual-band wilkinson divider/combiner

A technique for realising a compact frequency-selectable dual-band Wilkinson divider/combiner is presented in this study. To provide a frequency-selection function, the band-pass transmission-line transformer (TLT) in a dual-band device is replaced with a tuneable band-reject TLT. To realise this tuneable device, a variable capacitively loaded spur-line filter is proposed for its compact size. The theory based on an ideal transmission-line circuit is developed to provide a design procedure. The proposed circuits are demonstrated with simulated and measured results of a Wilkinson divider/combiner fabricated on FR4 substrate

Differential six-port reflectometer for determining dry rubber content of latex

This study presents the application of a differential six-port reflectometer to the design of a portable system for measurement of the dry rubber content (DRC) of latex. The proposed DRC measurement system consists of a 1 GHz reflectometer used with an open-ended coaxial-probe sensor, a temperature sensor, a display and a microcontroller. The complex permittivity and temperature of the rubber latex are measured, and a temperature-dependent model for DRC determination based on a dielectric mixture theory is used. The reflectometer performance is verified by comparing the measured complex permittivity with the results obtained from a commercial dielectric measurement system. Finally, the accuracy of the DRC measurement system is assessed by comparing the measured DRCs from different latex samples over the range of 10–40°C with the standard oven-drying method