In this paper, we present a THz attenuator based on the sub-wavelength metal s tructures. The T Hz attenuator is designed and fabricated on a copper foil. We measured TH z transmission of the at tenuator by means of terahertz time domain spectroscopy. The experimental results s how th at the attenuator ca n h ave a good frequency selectivity which depends on the polarization of THz radiati on. ...

This paper presents the 4~6GHz 6-bit MMIC digital attenuator with low phase shift. Phase compensation techniques were used in the MMIC design to reduce the phase shift. This attenuator is fabricated with 0.25μm GaAs PHEMT process. Simulation results of the developed MMIC chips in the 4~6GHz show that the 6-bit MMIC digital attenuator has 0.5dB resolution and 31.5dB dynamic attenuation range, in...

An attenuator supporting meander-line (ASML) slow wave structure (SWS) is proposed for a Ka-band traveling tube (TWT) and studied by simulations experiments. The ASML SWS simplifies the fabrication assembly process of traditional planar metal meander-lines (MLs) structures, employing an to support ML on bottom enclosure rather than welding them together sides. To reduce surface roughness molybd...

This paper presents the x-band 5-bit MMIC digital attenuator with low phase shift. Phase compensation techniques were used in the MMIC design to reduce the phase shift. This attenuator is fabricated with 0.2μm GaAs PHEMT process. Measurement results of the developed MMIC chips in the xband show that the 5-bit MMIC digital attenuator has 0.5dB resolution and 15.5dB dynamic attenuation range, inp...

We introduce a technique for ultrawideband measurement of terahertz pulses called dithered-edge sampling ~DES!. The technique makes use of a photoconductive receiver, but the detection bandwidth is much wider than that of the receiver alone. The key to increasing the bandwidth is the addition of an ultrafast optically triggered attenuator that chops the terahertz pulse before its detection. The...

We have developed a continuously tunable, broadband terahertz attenuator with a transmission tuning range greater than 10. Attenuation tuning is achieved electrically, by simply changing the DC voltage applied to a heating wire attached to a bulk silicon wafer, which controls its temperature between room temperature and !550 K, with the corresponding free-carrier density adjusted between !10 cm...

We present a practical and inexpensive method for creating physical objects that cast different color shadow images when illuminated by prescribed lighting configurations. The input to our system is a number of lighting configurations and corresponding desired shadow images. Our approach computes attenuation masks, which are then printed on transparent materials and stacked to form a single mul...

With the aim of achieving constant insertion loss, this paper presents the design of a 24 GHz reflectivetype phase shifter (RTPS) integrated with a switched -attenuator for phased array transmitters. Three RTPS circuits with hybrid coupler and capacitive-type reflective loads are cascaded to obtain required phase-shift. Accumulation-mode MOS (AMOS) varactors are used as reflective loads for pha...

A genetically structured mathematical model of the trp attenuator in Escherichia coli based on known coupling mechanisms of the transcription of the trp leader region and translation of the trp leader peptide region is proposed. The model simulates, both qualitatively and quantitatively, the effects of tryptophan on the repression of cloned gene products. It shows that repression by attenuation...