Reinhard Mikuta

An improvement of defected ground structure lowpass/bandpass filters using H-slot resonators and coupling matrix method

A novel compact wideband high-rejection lowpass filter (LPF) using H-DGS is presented. The proposed filter has neither open stub nor cascaded high-low impedance elements. It consists of two coupled H-slots in the ground plane along with a compensated line. The effect of the new slot on the filter performance is examined. The comparison with the conventional filters shows that the proposed one guarantees a large rejected-band of 20dB from 2.5 to 16 GHz. Experimental measurements by means of HP8719D network analyzer agree well with simulated results which are carried out by Microwave Office. Based on H-DGS LPF Structure, a novel bandpass filter (BPF) will be is designed and tested verified by using both J-inverter and coupling matrix methods.

Characterization of non-dispersive infrared gas detection system for multi gas applications

Abstract In this work, we present a low cost multi gas detection system for simultaneous measurement of up to three gases. The main conclusions are based on the investigation of the concentrations of CO2 gas as well as of CH4 gas and of H2O vapor. It was found that the continuous heating of the IR source and the absolute values of thermopile voltages are not suitable parameters for the gas detection because of their high sensitivity to the influence of temperature and/or gas flow parameters. A sine like signal is preferential for our measurement system. The amplitude of the sine is very stable and is proportional only to the concentration of particular gas (according to the optical filter) and is not dependent on the concentration of other gases or on temperature. In this way, the CO2 gas concentration can be measured from 50 ppm to 400000 ppm with the same measurement setup. The lowest detectable concentration of CH4 was about 500 ppm.

Messanordnung zur kapazitiven Luft- und Gasfeuchtemessung (Test Set-up for the Capacitive Humidity Measurement)

In diesem Beitrag wird eine einfache und kostengünstige Schaltung zur Messung der relativen Luft- bzw. Gasfeuchte mittels kapazitiver Feuchtesensoren beschrieben. Die Messung der relativen Feuchte wird auf eine Quotientenbildung zurückgeführt, wobei einer der beiden Feuchtesensoren als Referenzelement ausgeführt ist. Der Quotient führt zu einem digitalen Informationsparameter, einer Zählmenge. In this paper a low-cost humidity sensor is described. The sensor consists of two capacitive elements, with one of the elements implemented as a reference. The other element measures the relative humidity of air or other gases. These two signals can be transformed by a simple circuit to a digital output parameter for further data processing.