Practical Antenna Handbook 5/e, 5th Edition

CHAPTER 7Large Wire Loop Antennas

Loop antennas are characterized as small or large depending on the dimensions of the loop relative to the wavelength of the operating frequency. These two types of loops have different characteristics, work according to different principles, and serve different purposes. Small loops are those in which the current flowing in the wire has approximately the same phase and amplitude at every point in the loop (which fact implies a very short wire length, i.e., less than about 0.2λ). Such loops respond to the magnetic field component of the electromagnetic radio wave. A large loop antenna has a wire length greater than 0.2λ, with most being λ/2, 1λ, or 2λ. The current in a large loop varies along the length of the ...