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SUMMARY:A simple method of evaluating dielectric properties of dielectric 
 layers at sub-terahertz frequencies using tapered dielectric waveguides
DTSTART;VALUE=DATE-TIME:20220706T153500Z
DTEND;VALUE=DATE-TIME:20220706T155000Z
DTSTAMP;VALUE=DATE-TIME:20260414T154527Z
UID:indico-contribution-811@events.ncbj.gov.pl
DESCRIPTION:Speakers: Valeri Mikhnev (CENTERA Laboratories\, Institute of 
 High Pressure Physics PAS)\nThe accurate knowledge of constitutive paramet
 ers of dielectric materials is demanded in numerous applications\, from de
 signing quasi-optical components\, antennas and sensors to nondestructive 
 testing. Terahertz time-domain spectroscopy (THz-TDS) is a recognized tech
 nique of the broadband material characterization\, but it requires a well-
 adjusted measurement setup\, special sample holders etc. Alternatively\, t
 he dielectric properties of materials can be evaluated using such widely u
 sed sub-THz apparatus as a vector network analyzer with frequency extender
 s. To this end\, they must be additionally equipped with the dielectric me
 asurement cells and corresponding software while the free-space measuremen
 ts require a careful preparatory work similar to THz-TDS systems.\nWe prop
 ose a simple transmission-mode method of evaluating dielectric properties 
 of thin-sheet materials utilizing a pair of metal-to dielectric waveguide 
 transitions connected to the sub-THz frequency extenders. The dielectric s
 ample under test is placed in the gap between two open-ended tapered diele
 ctric waveguides (DW). The dimensions of DW\, length and shape of the tape
 r have been chosen to ensure the best operation in the near field. The mai
 n advantage of the tapered DW is an extremely low reflection from the tape
 r both for outcoming and incident waves that makes the parasitic interfere
 nce in the measurement area negligible. This allows to use simple formulas
  for extracting the constitutive parameters of dielectrics. Due to small d
 imensions of DW\, the illuminated spot of the sample is even smaller than 
 in a free-space setup with focusing lenses.\nThe method was tested using t
 he frequency extenders V15VNA2-T/R (frequency range up to 75 GHz) and samp
 les of Teflon\, high-density polyethylene\, high-frequency laminate RT/dur
 oid 5870\, alumina with the dielectric constant in the range 2.08 to 9.8 a
 nd thickness of 0.8 mm to 2.4 mm. The measurement error in all cases was a
 bout 1-3%.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/811/
LOCATION:Novotel Warszawa Centrum Róża
URL:https://events.ncbj.gov.pl/event/75/contributions/811/
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