Review of progress in the field of anomalous dispersion

It may be concluded from the current literature that definite progress has been made in studies of electrical anomalous dispersion and may be arbitrarily summed up with the following observations: First, the scope and nature of the electrical measurements have been greatly expanded. Second, an increased amount of descriptive matter on ultra high frequency technique involving theory of circuits and design of instruments reflects a fraction of the important work being done in different bands of electrical spectrum. Many of these technical descriptions have been presented in a clearer form than in previous classical treatments. Third, increased attention has been given to the behavior of the high molecular weight compounds, particularly of the synthetic polymer family. Fourth, accounts have been given for the application of high frequency, particularly in radio frequency heating. Fifth, it is encouraging that more research has been done on electrical behavior of surfaces and thin films. This latter avenue of approach is of importance to the insulation field. It is observed that in many of the papers care has been taken in the original project to prepare and carefully control the chemical systems being studied. It still behooves every investigator in dielectric constant, power factor and conductivity investigations to carefully prepare material to be measured or to know the past history of the materials. This is particularly true of the high molecular weight compounds such as synthetic polymers which are largely influenced in their nature by the methods of preparation. It is still urged that when various chemical substances are investigated for anomalous dispersion effects that measurements be extended over wider ranges of the electrical spectrum. Certainly, with the increased knowledge of high frequency technique such an extension into higher frequency ranges will be made possible.