Solid Waveguide Research Articles

Unidirectional Wave Propagation in an Inhomogeneous Solid State Plasma Waveguide

Electromagnetic wave propagation through a semiconductor with a non-uniform density distribution in transverse magnetic fields has been studied theoretically. It is shown that waves in the UHF band will propagate in only one direction, determined by the directions of the external magnetic field and the density gradient. The experimental conditions required to observe such a wave are given.

Propagation in a Solid State Plasma Waveguide in a Transverse Magnetic Field

Microwave propagation at 24 Gc was observed in a waveguide filled by IhSb containing an electron-ion plasma at 77°K. A transverse magnetic field in excess of 5 KOe was used, and the transmission increased exponentially with increasing magnetic field intensiy. The transmission showed a sharp angular dependence on the field direction and a strong nonreciprocal character which may be of use in millimeter or submillimeter wave devices. Measurements of the phase shift in the InSb showed that the wave is transmitted only along the side of the waveguide determined by the magnetic field and power flow directions, and that the wave length increases with increasing magnetic field.

Velocity and Attenuation of a Narrow-Band, High-Frequency Compressional Pulse in a Solid Wave Guide

The usual solutions describing the propagation of continuous waves in solid plates and cylinders fail to predict the observed velocity and attenuation, and secondary signals, in the propagation of a narrow-band pulse of compressional waves of carrier frequency of the order of 10 Mc/sec. It is shown that all these factors may be accounted for if a slightly different form of solution is chosen, to fit more closely the conditions under which the propagation takes place. Both plates and cylinders are treated theoretically, and methods of obtaining approximate solutions of the modified frequency equations are discussed. The results of this analysis agree closely with those derived by other, less exact methods, which commence with the assumption that the solid medium behaves very similarly to a fluid. The relation of this work to the propagation of pulses at low frequencies is also discussed. A method of analysis similar to that employed here is also necessary to predict experimental results in the propagation of pulses in multilayered wave guides of any configuration, mechanical or electromagnetic.

Dispersion Effects in Ultrasonic Waveguides and their Importance in the Measurement of Attenuation

A study is made of the possible sources of error when the pulse technique is used to determine the absorption of compressional waves (of frequency 10-100 Mc/s) in low-loss solid materials, the specimens being cylindrical and acting as `waveguides'. A theoretical analysis is made of a cylindrical guide with transmitting and receiving transducers of arbitrary size: for simplicity the medium is assumed initially to behave as a fluid, and equations describing the possible modes of propagation and their relative amplitudes for a `piston source' transmitter are developed. The case of transmitting and receiving transducers of diameter equal to that of the guide is treated in detail, and the theoretical voltage at the receiving transducer is plotted as a function of distance from the source; the effects of interference between the several modes of propagation are apparent. The analysis is extended to solid waveguides, where reflections at the walls of the guide produce a partial conversion to transverse waves. The practical effect of this on mode interference is discussed, and the final results of the analysis are compared with experiment. The estimated errors in the measurement of attenuation are tabulated for several frequencies and compared with the intrinsic absorption in fused silica and single crystal germanium.