Overview

From APPLIED MICROWAVE & WIRELESS, VOL. 12, NO. 11, NOVEMBER 2000

For most of us, discoveries in the art are rare. My books reviewed the contributions of many engineers and contained a limited number of original ideas. I recall many excited moments during my career that faded upon the realization that a discovery was actually a measurement error, misunderstanding or rediscovery.

In 1997, an engineer requested that I examine his measured data for an inductor. The data was unexpected, so I decided to measure a simple solenoid with a network analyzer. The analyzer display stunned me. This moment of excitement would not fade. The industry s accepted and century-old inductor model was wrong. Why had no engineer before me performed this simple experiment and written about it? The significance of the experiment began to unfold at my desk as I examined the problem mathematically. As is often the case, new knowledge is both satisfying and useful. The purpose of this paper is to describe new filter and oscillator structures suggested by the new model. First, I will review the historic inductor model, then the new one.

The Historic Model

One need only ponder a solenoid inductor to realize that the close spaced turns are capacitively coupled. But how do you measure capacitance that is shorted by a turn of wire? Webster [12] solved this problem by building a parallel-resonant mode oscillator using an inductor...