It is known that if a conductor resides in the neighboring of an antenna with a small distance relative to the wavelength, it induces a reverse current on the conductor. This paper involves the unavoidable coupling effects on some common types of LF antennas, due to the large wavelength in this frequency band. In particular, after some discussions about top-loaded antennas, the coupling effect ...

E lectrically small antennas have been an important part of communications engineering since the beginning. Whether they are small compared to the extremely long wavelengths used at the lowest radio frequencies, or intended to save space in GHz-range wireless devices, the basic principles are the same. This tutorial will review those principles, with primary attention to describing the performa...

Antennas for hand-held communication devices are necessarily small, and typically use wavelengths λ that are large compared to the size of the antenna. This typically implies that the magnitude of the antenna reactance X (= imaginary part of the antenna impedance) is large compared to that of its radiation resistance Rrad (which is related to the time-average radiated power P and the peak curre...

The voltage difference between the two arms of the antenna is On the right is Fig. 86 from [2]. In general the electric field is related to the scalar and vector potentials by E = −∇V − ∂A/∂t = −∇V + iωA, assuming a time dependence of the form e−iωt. Then, ∫ 2 1 E · dl = V1 − V2 + iω ∫ 2 1 A · dl. However, close to a small linear dipole antenna the electric field is much larger than the magneti...

detection of stealth targets calls for employment of high-power radars which itself relies on usage of high-gain antennas like large parabolic reflectors. in the past few years, using of an array with many small reflectors instead of a large reflector antenna has been considered. this method provides enhanced eirp by a factor of n2 where n is the number of array antennas. regarding improvement ...