Small Antenna Design

APPENDIX C

The Small Loop

Loop antennas come in a variety of shapes but the most common single-turn shapes are the circle and the rectangle. In this appendix I use results from Appendices A and B to find the radiated field for a small circular loop carrying a uniform (independent of position) current. Figure C.1(a) shows the setup for a loop in the x-y plane, and Figure C.1(b) shows the decomposition of a current-length element. As pointed out in Chapter 2, the vector orientation of the radiated fields depends on the direction of the current source. In electromagnetic theory, the current density is given a vector character, and when current density times volume, , is converted into total current times length, it is the length element that is ...