RSI Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

May 2010

Volume 81, Issue 5, Articles (05xxxx)

Return to All Sections
back to top
RSS Feeds
back to top Electronics; Electromagnetic Technology; Microwaves

X-ray microfabrication and measurement of a terahertz mode converter

T. H. Chang, B. Y. Shew, C. Y. Wu, and N. C. Chen

Rev. Sci. Instrum. 81, 054701 (2010); http://dx.doi.org/10.1063/1.3385685 (4 pages) | Cited 1 time

Online Publication Date: 4 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Mode converters are critical for frequency-tunable terahertz gyrotrons. This study reports the development of a broadband TE02 mode converter centered at 0.2 THz. An octafeed sidewall coupling structure was employed and the mode purity was analyzed. The converter was built using the technique of x-ray microfabrication. The x rays irradiated on the SU-8 resist and generated a template of very high thickness of 1.295 mm. Pulse electroplating technique was used to deposit copper on the structure along the template. The parts then went through precise machining and the residual resist was removed via high-flux radical etching. A computer-aided diagnostic system was introduced to measure the performance of the converter. Results suggest that the frequency response of resistivity should be taken into consideration for the devices in terahertz region.
Show PACS
84.40.-x Radiowave and microwave (including millimeter wave) technology
07.10.Cm Micromechanical devices and systems
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.15.Pq Electrodeposition, electroplating
85.40.Hp Lithography, masks and pattern transfer
81.65.Cf Surface cleaning, etching, patterning

High electric field effects on gigahertz dielectric properties of water measured with microwave microfluidic devices

Chunrong Song and Pingshan Wang

Rev. Sci. Instrum. 81, 054702 (2010); http://dx.doi.org/10.1063/1.3405975 (5 pages) | Cited 3 times

Online Publication Date: 5 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Silicon microstrip line devices with 260 nm planar microfluidic channels are fabricated and used to investigate water dielectric saturation effects. Microwave scattering parameter measurements are conducted from 1 to 16 GHz under different uniform dc electric fields. When the applied dc field is increased to ∼ 1 MV/cm, the measured transmission coefficient S21 is increased up to 18 dB, which indicates a large change in water dielectric properties. Extracted water permittivity (ε = ε′+jε″) shows that ε′ and ε″ are changed up to 70% and 50%, respectively.
Show PACS
77.22.Ch Permittivity (dielectric function)
84.40.-x Radiowave and microwave (including millimeter wave) technology

A tunable radio-frequency magnetic probe

B. Sun, G. Y. Yuan, W. G. Huo, and Z. F. Ding

Rev. Sci. Instrum. 81, 054703 (2010); http://dx.doi.org/10.1063/1.3402288 (8 pages) | Cited 1 time

Online Publication Date: 7 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A tunable center-tapped transformer is proposed to increase the output of a rf magnetic probe and improve the signal-to-noise ratio. The tuning is implemented by a variable capacitor connected parallel with the primary winding of the tunable center-tapped transformer. Undesirable common-to-differential conversion is reduced by installing a compensating capacitor. In addition, a planar Faraday shield is installed between the windings of the transformer to further suppress the electrostatic coupling. It is found that tuning the variable capacitor can result in a resonance in the output voltage of the rf magnetic probe. The largest output voltage, achieved with the tunable magnetic probe under the optimal condition, is higher than that with a conventional one by an order of magnitude. Effects of the compensating capacitance on the common-mode output voltage are studied and discussed. Influences of parameters such as cable length, the coupling coefficient, and the step-up ratio of the transformer on the output voltage are also presented. Analytical derivations and numerical calculations based on the equivalent circuit are performed to elucidate the characteristics of the differential mode.
Show PACS
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables

Microcontroller-based binary integrator for millimeter-wave radar experiments

Pekka Eskelinen, Jukka Ruoskanen, and Jouni Peltonen

Rev. Sci. Instrum. 81, 054704 (2010); http://dx.doi.org/10.1063/1.3424852 (4 pages)

Online Publication Date: 12 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An easily on-site reconfigurable multiple binary integrator for millimeter radar experiments has been constructed of static random access memories, an eight bit microcontroller, and high speed video operational amplifiers. The design uses a raw comparator path and two adjustable m-out-of-n chains in a wired-OR configuration. Standard high speed memories allow the use of pulse widths below 100 ns. For eight pulse repetition intervals it gives a maximum improvement of 6.6 dB for stationary low-level target echoes. The doubled configuration enhances the capability against fluctuating targets. Because of the raw comparator path, also single return pulses of relatively high amplitude are processed.
Show PACS
84.40.Xb Telemetry: remote control, remote sensing; radar
84.40.-x Radiowave and microwave (including millimeter wave) technology
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology

High frequency, high time resolution time-to-digital converter employing passive resonating circuits

Giancarlo Ripamonti, Andrea Abba, and Angelo Geraci

Rev. Sci. Instrum. 81, 054705 (2010); http://dx.doi.org/10.1063/1.3432002 (7 pages)

Online Publication Date: 28 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A method for measuring time intervals accurate to the picosecond range is based on phase measurements of oscillating waveforms synchronous with their beginning and/or end. The oscillation is generated by triggering an LC resonant circuit, whose capacitance is precharged. By using high Q resonators and a final active quenching of the oscillation, it is possible to conjugate high time resolution and a small measurement time, which allows a high measurement rate. Methods for fast analysis of the data are considered and discussed with reference to computing resource requirements, speed, and accuracy. Experimental tests show the feasibility of the method and a time accuracy better than 4 ps rms. Methods aimed at further reducing hardware resources are finally discussed.
Show PACS
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
06.30.Ft Time and frequency
02.30.-f Function theory, analysis

Transportable high-energy high-power generator

B. M. Novac, I. R. Smith, P. Senior, M. Parker, and G. Louverdis

Rev. Sci. Instrum. 81, 054706 (2010); http://dx.doi.org/10.1063/1.3428726 (5 pages) | Cited 1 time

Online Publication Date: 28 May 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High-power applications sometimes require a transportable, simple, and robust gigawatt pulsed power generator, and an analysis of various possible approaches shows that one based on a twin exploding wire array is extremely advantageous. A generator based on this technology and used with a high-energy capacitor bank has recently been developed at Loughborough University. An H-configuration circuit is used, with one pair of diagonally opposite arms each comprising a high-voltage ballast inductor and the other pair exploding wire arrays capable of generating voltages up to 300 kV. The two center points of the H configuration provide the output to the load, which is coupled through a high-voltage self-breakdown spark gap, with the entire autonomous source being housed in a metallic container. Experimentally, a load resistance of a few tens of Ohms is provided with an impulse of more than 300 kV, having a rise time of about 140 ns and a peak power of over 1.7 GW. Details of the experimental arrangement and typical results are presented and diagnostic measurements of the current and voltage output are shown to compare well with theoretical predictions based on detailed numerical modeling. Finally, the next stage toward developing a more powerful and energetic transportable source is outlined.
Show PACS
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
88.80.fh Supercapacitors
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close