4. POSSIBLE RESONANCE CHARACTERISTICS OF HABITABLE SPACE The term resonance implies the existence of reflective boundaries and the build-up of high field amplitudes (equation 15) by multiple reflections. A standing-wave field alternates between electric and magnetic energy storage and is sustained by the energy coupled into the resonator. The Q-factor (11) can be calculated for simple cases (Appendix B) or determined, for example, by exciting a resonant structure with pulsed microwaves and measuring the ringing time t yielding After the time t, the energy content of the resonance has dropped to 1/e of its starting value. 4.1. Cavity Resonator In general, any closed and somewhat reflecting cavity will support resonances regardless of its shape if only its dimensions are fixed and large compared to the wavelength X . In most cases such conditions are met by habitable space. The spectrum of possible resonances for a given XQ becomes increasingly dense with growing cavity dimensions. The number of allowed resonance modes for a given geometry (see examples in Appendix B), the so-called "mode density", is approximately given by (Wilson et al., 1946, Kinzer and Wilson, 1947) 3 For example, a room of the size 4 x 5 x 2.5 = 50 m can exhibit, in principle, on c the order of Nv« 2.3 x 10 resonance (x = 12 cm) modes. These modes are expected to exhibit low Q-factors (Q < 10) in houses owing to the fact that walls usually are made from dielectric materials and reflect only part of the incident wave. Metal walls on the other hand are subject to ohmic (field-induced currents) and dielectric losses (wall coatings). In addition, the presence of lossy interior objects will dampen the resonance field.
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