Abstract :
It appears to be common practice in almost all introductory texts in electromagnetic theory to introduce radiation by means of "currents" in free space, rather than on a conducting structure. Then the assumption is made, often implicitly, that the results are applicable to currents on conductors. Two questions then arise: What justification is there for using a potential integral for inhomogeneous media? How can a metallic structure radiate energy (from what appears to be a distributed source along the antenna) when it has zero tangential electric field? In contrast to this unsatisfying approach, the authors develop in this paper a potential integral for the conductor problem which contains the unknown, but measurable, current on the conductor. The integral is identical in form to the one commonly used for currents in free space, but the meaning of all terms is now clear, and the assumption that the free-space potential integral is applicable to the conductor problem is shown to be unnecessary. Finally, the authors show that an appealing viewpoint on the concept of energy being radiated from each point on the antenna is that primary radiation is from the feed gap alone and that the antenna structure acts as a scatterer or reradiator.
