Billy F. Riddle

Complex permittivity measurements of common plastics over variable temperatures

In this paper, we present complex permittivity data at microwave frequencies (approximately 10 GHz) for many common plastics over a temperature range of 122 to 375 K. The measurements were made with a TE/sub 01/spl delta// dielectric resonator placed inside an environmental chamber. Data are presented for the following materials: acrylonitrile butadiene styrene, polytetrafluoroethylene, cross-linked polystyrene, tetrafluorethylene-perfluorpropylene, polypropylene, polysulfone, polymethylmethacrylate, polyvinyl chloride, polycarbonate, high-density polyethylene, polyoxy-methylene (acetal homopolymer), and polyamide.

Uncertainty of complex permittivity measurements by split-post dielectric resonator technique

Abstract Split-post dielectric resonators operating at frequencies 1.4–5.5 GHz were used to measure complex permittivity of single crystal standard reference dielectric materials with well known dielectric properties previously measured by other techniques. Detailed error analysis of permittivity and dielectric loss tangent measurements has been performed. It was proved both theoretically and experimentally that using split post resonators it is possible to measure permittivity with uncertainty about 0.3% and dielectric loss tangent with resolution 2×10 −5 for well-machined laminar specimens.

Time-Domain Free-Field Measurements of the Relative Permittivity of Building Materials

Time-domain free-field measurements comprised the dielectric properties of several common building materials using dual-ridged guide antennas and 1 mtimes1 m samples placed on an optical table covered with an absorber. The samples are polycarbonate, gypsum, plywood, a brick wall, and a concrete wall. Time gating and deconvolution are used to isolate a samples front and back surfaces to obtain the measured reflection coefficients (RCs) and transmission coefficients. Theoretical reflection and transmission equations were generated from a plane-wave model. Relative permittivity is obtained by varying the parameters in the Kirkwood-Fuoss equation until a best fit between the theoretical and measured reflection and transmission coefficients is obtained.

Dielectric and Magnetic Measurements: A Survey of Nondestructive, Quasi-Nondestructive, and Process-Control Techniques" *

A review of the most common methods for nondestructive permittivity and permeability measurements is presented. Transmission-line techniques, coaxial apertures, open resonators, surface-waves, and dielectric resonator methods are examined. Measurements on bulk, thin materials, and thin films are addressed. Measurement fixtures that can be used as sensors are highlighted. The frequency range of applicability and typical uncertainties associated with each method are addressed.

Impedance control for critically coupled cavities

Cavity resonators are often used in low phase noise oscillators that utilize carrier suppression. These oscillators are employed in systems that measure phase noise in frequencies as high as 100 GHz. In order to achieve the maximum suppression needed in these low noise designs, the cavity must be operated at critical coupling. However, this large coupling level loads the cavity, which significantly lowers its quality factor and shifts its resonant frequency. In this paper, we present a matching technique that can be used to minimize these loading effects by controlling the input impedance of the cavity and optimizing its response at resonance, thus producing the maximum amount of carrier suppression

A 40 GHz Air-Dielectric Cavity Oscillator with Low Phase Modulation Noise

Abstract: We describe a 40 GHz cavity stabilized oscillator (CSO) that uses an air-dielectric cavity resonator as a frequency discriminator to reduce the phase modulation (PM) noise of a commercial 10 GHz dielectric resonator oscillator (DRO) frequency multiplied by four. Low PM noise and small size were the main design goals. Single sideband (SSB) PM noise equal to −128 dBc/Hz at a 10 kHz offset from the carrier frequency is achieved for the CSO. In addition, we report on the PM noise of several Ka-band components.

High spectral purity oscillator at 40 GHz: Design using air-dielectric cavity

We describe the design of a low-phase modulated (PM) noise 40 GHz oscillator that uses a conventional air-dielectric cavity resonator as a frequency discriminator to clean up the PM noise of a commercial 10 GHz dielectric resonator oscillator (DRO) multiplied by four. The main features of this design incorporate (1) unloaded cavity quality factor (Q) of 30,000, (2) high coupling coefficient, (3) large carrier suppression by use of interferometric signal processing, (4) large operating signal power of approximately 1 Watt (W), and (5) relatively small size.