Microwave interferometry appears to be a promising method for the study of wave and mass velocity in shocked dielectric materials. This paper discusses the mathematics concerning the frequencies and amplitudes in the microwave reflections from the shock wave and from an impacting piston which drives the shock into a nonreacting porous solid. Methods for the determination of the state variables in the compressed region between the shock wave and the piston are given. In this paper, these methods have been confirmed by experimental measurements in nonenergetic materials in which there is no ionization from chemical reaction. The microwave reflection from the shock wave traveling through an inert media is shown to result from a dielectric discontinuity at the wave front. Studies on energetic materials (explosives and propellants) are considered in a companion paper where ionization associated with the chemical reactions is required to explain the increased reflection from the shock front.

Shocked porous ball powders have been investigated by means of microwave interferometric techniques. Equations developed for interferometric measurements on inert materials apply for energetic materials until reaction at the shock front begins. As reaction begins, the microwave interferometer (MI) output exhibits characteristic changes in both the absorption and reflection of the microwave signal. These changes have been related to hot spot development at the shock front. The hot spots in a reacting bed have been experimentally approximated to a first order by including metallic particles in unreacting beds and measuring their effects on the propagation of microwaves. With the aid of dielectric measurements of the metallized beds, hot spot concentrations as a function of time were predicted from the MI output of reacting beds.

opment, t h a t d e t e c t s a vehicle's presence by measuring i t s m a g n e t i c s i g n a t u r e i n t h e r o a d w a y. An o p t i m i z e d t w o a x i s Brown fluxgate magnetometer i s used as the t r a n s d u c e r w i t h a d i g i t a l n u l 1 i n g l o o p t o p e r f o r m s e n s o r o f f s e t n u l l i n g and l o g i c f u n c t i o n s. An FM telemetry link containing three encoded tones conveys t h e roadway emplanted SPVD vehicle presence and device s t a t u s i n f o r m a t i o n t o a r o a d s i d e c o n t r o l u n i t w h i c h may i n t e r f a c e w i t h o t h e r t r a f f i c c o n t r o l s y s t e m s. A m i n i m u m o n e y e a r o p e r a t i o n a l l i f e t i m e i s a n t i c i p a t e d i n a roadway with a 20,000 v e h i c l e s / d a y t r a f f i c f l u x .

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