Current Issue : January - March Volume : 2013 Issue Number : 1 Articles : 4 Articles
This paper presents an alterative implementation of a shunt open-circuited stub formultilayer microwave circuit.With making use\r\nof the proposed implementation, a simple and compact bandstop filter with a district bandstop characteristics and a first spurious\r\nat the third harmonic is proposed. The proposed filter exhibits about 12.5% fractional bandwidth of -10 dB signal rejection at\r\nthe center frequency of 2.04 GHz and flat group delay at the pass bands. Besides, by cascading a number of the proposed bandstop\r\nfilters designed at the different frequencies, multiband bandstop filters can be easily realized. A dual- (tri-) band design at the\r\ncenter frequencies of 2 GHz and 3 GHz (and 4 GHz) is designed, realized, and measured. The proposed bandstop filter well suits\r\nthe nowadays multilayer and compact radio frequency integrated circuit design....
Transformer-based shunt single pole, double-throw (SPDT) switches are analyzed, and design equations are provided. A mm-wave\r\ntransformer-based SPDT shunt switch prototype was designed and fabricated in 90nm digital CMOS process. It has a minimum\r\ninsertion loss of 3.4 dB at 50 GHz from the single pole to the ON-thru port and a leakage of 19 dB from the single pole to the\r\nOFF-thru port. The isolation is 13.7 dB between the two thru ports. Large signal measurements verify that the switch is capable\r\nof handling dBm of input power at its 1 dB compression point. The fabricated SPDT switch has a minute active area size of\r\n60 Ã?µmÃ?â?? 60 Ã?µm....
The paper describes the complex permittivity measurements of textiles and leathers in a free space at 330 GHz. The destructive\r\nrole of the Rayleigh scattering effect is considered and the angular-invariant limit for an incidence angle has been found out\r\nexperimentally within 25ââ?¬â??30 degrees. If incidence angle exceeds this critical parameter, the uncertainty caused by the Rayleigh\r\nscattering is drastically increased preventing accurate measurements of the real and imaginary parts of a bulky material. The\r\nphenomenon must be taken into consideration in predicting shielding effectiveness of materials covering hidden object in\r\nconcealed threat detection with millimeter-wave radar systems....
A commercial vinyl ester resin supplied by Hetron Chemical Pty. was reinforced with varying percentages by weight of sawdust.\r\nThe sawdust particles were sieved into 3 different sizes, which were <300 Ã?µm, 300ââ?¬â??425 Ã?µm, and 425ââ?¬â??1180 Ã?µm, respectively, with a\r\nview to increase its fracture toughness for civil and structural applications. The sawdust used varied from 0% w/t to 15% w/t in\r\nstep of 5% w/t. For higher w/t% of sawdust, the mixture would be too sticky to be mixed and cast. The cast composites were cured\r\nin ambient conditions and then postcured in microwave irradiation. They were then tested for fracture toughness using short\r\nbar tests. The values of fracture toughness of the composites increased with increasing particulate size, and this is due to the size\r\ndistribution of the filler. It was found that the optimum amount of sawdust (425ââ?¬â??1180 Ã?µm) was 15% w/t, with which the increase\r\nin fracture toughness was 126% as compared to neat resin and the reduction in cost was 15%. Furthermore, the optimum amount\r\nof sawdust (300ââ?¬â??425 Ã?µm) was also 15% w/t, with which the increase in fracture toughness was 28.3% as compared to neat resin\r\nand the reduction in cost was again 15%....
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