AbstractsEngineering

An apparatus has been constructed in which the output of a 5 mc/s crystal-controlled oscillator of short-time frequency stability 1 in 108 is frequency multiplied to frequencies of 270 mc/sec and 2970 mc/sec. The oscillator frequency is variable by ± 600 cps by varying the capacity across the crystal, the frequency deviation from 5 mc/sec being measured within 0.1 cps by comparison with a 5 mc/s frequency standard and standard tuning forks. By obtaining resonance-curves of a high-Q resonant cavity at 270 mc/s measurements have been made of the dielectric constant and loss tangent of dry air and three dry non-polar gases. The loss tangent of each of the gases at N. T. P. is shown to be less than 5 x 10-6. Preliminary similar measurements on dry air have been made at 2970 mc/s. The application of the apparatus to measurements on liquids and solids is discussed in detail.