Theory and experiment have run hand-in-hand leading the way toward new concepts and new radiating and receiving structures throughout the history of antennas. Sometimes new antennas were developed through experiment with supporting analysis coming later and perhaps pointing the way to optimization. In other instances, the analysis pointed the way with experiment showing that the analytical model could be achieved in the physically real world. Regardless of the origin of the idea, the most effective results have occurred when the theoretical analysis and the experimental measurements come together. For the experimental and theoretical results to agree, both must describe a model that has exactly the same electromagnetic boundary conditions. Since it is rarely possible to have identical models in the theoretical and the real world, the models must be critically examined, their differences identified, and at least approximately taken into account. Theoretical concepts such as “less than” and “thin” must be reconciled in each experimental model. Similarly, the measurement process must be critically examined to understand exactly what is being measured. Are sampling probes extracting enough power to distort the interference pattern on the transmission line? Are the fields being sampled too close to a discontinuity? Are loop probes being excited only in their basic mode? Finally, there is always the basic question in antenna experiments: “To what in the world are the elements really coupling?”

Measurement procedures on uniform sections of transmission lines have been discussed many times [1–7].