Improvement in efficiency-bandwidth product in small dielectric loaded antennas

Direct Measurement of Small Antenna Radiation Efficiency by Calorimetric Method

“…Fluctuations of about its controlled constant average which are fast compared to the time constant of the box cannot penetrate deeply into the insulation. Inspection of the characteristic equation associated with (8) leads to the identification of a thermal "skin depth" (10) where denotes the frequency of a sinusoidal variation of temperature over time. The similarity to the skin effect in electromagnetics is not accidental since the same parabolic partial differential equation applies.…”

“…The similarity to the skin effect in electromagnetics is not accidental since the same parabolic partial differential equation applies. Equation (10) suggest that the controller should be designed for fast response, allowing for some overshoot to obtain a rapidly oscillating, exponentially damped return of to its constant reference value. Fig.…”

“…An accurate efficiency measurement technique of general Color versions of Figs. 5,9,10,11,12,14 are available online at http://ieeexplore.ieee.org.…”

“…The Wheeler cap method was originally proposed for electrically small radiators which would not include mobile terminals in general. Attractive for its low cost, it is widely employed also beyond this limitation [9], [10], although conceptual difficulties [3], [11], [12] and practical problems (cavity resonances) [13], [14] rise (see Section V). Good results have nevertheless been reported in many applications [15], [16], and repeatability has been rated superior to 3-D pattern integration [7].…”