An experimental and theoretical investigation into methods concerned with "reflection loss" for microwave absorbing materials

There have been many recent advances in telecommunications, which have led to increased attention in reducing microwave interference. However, some vital persistent problems in the field of microwave absorption have hindered such research despite the amount of work published. Indeed, an inaccurate method of characterization and interpretation of experimental results using reflection loss has become common-place and is regularly used. It is demonstrated here that this established theory of reflection loss contradicts fundamental principles in transmission-line theory and as a result is used to interpret experimental data wrongly. The input impedance in transmission-line theory has been distorted in microwave absorption reports and the concept of impedance matching from reflection loss is illogical. In the present work, using newly obtained experimental data, a simple procedure has been developed that successfully relates such data with the correct theory. This involves classifying the interactions between material and microwave into two distinct categories, namely isolated interface and material acting as a circuit element. The problems associated with the previous concepts defined by the term reflection loss, RL, have been clarified. The sophisticated relationship between reflection coefficient and input impedance has been discussed.