Slow wave time-domain reflectometer point level sensor

摘要: Slow wave, time-domain reflectometer based point level sensors and instruments. Such instruments include a transmission line having an inner conductor, outer shield that extends over conductor so as to define gap between the shield, dielectric material fills gap, except at point, thereby defining space, access opening for enabling being sensed fill space when is present. According invention has permittivity substantially different from sensed. Further included are pulse generator generating pulses on line, processing unit determining whether space. Beneficially helically wound around core, creating slow wave line.