Abstract: An electromagnetic gradiometer (EMG) survey kit includes a lightweight man-carry boom about ten feet long. Matched magnetic dipole antennas are attached at each end and connected to a differential EMG receiver able to make measurements in the picoTelsa range. A pair of staging tripods allow the man-carry boom to be prepared for field use and assist the user in positioning themselves under a shoulder sling. An air core transmitter loop antenna and a low frequency square wave generator are spotted nearby a survey on the ground surface. Its emissions will illuminate any underground conductive structures with primary electric field waves. These in turn will reradiate near field magnetic waves that can be detected by the EMG receiver while walking around in a search area on the ground surface. GPS navigation receivers are used to locate and log the changing positions of the EMG receiver and stationary loop transmitter.

Abstract: An electromagnetic gradiometer (EMG) survey kit includes a lightweight man-carry boom about ten feet long. Matched magnetic dipole antennas are attached at each end and connected to a differential EMG receiver able to make measurements in the picoTelsa range. A pair of staging tripods allow the man-carry boom to be prepared for field use and assist the user in positioning themselves under a shoulder sling. An air core transmitter loop antenna and a low frequency square wave generator are spotted nearby a survey on the ground surface. Its emissions will illuminate any underground conductive structures with primary electric field waves. These in turn will reradiate near field magnetic waves that can be detected by the EMG receiver while walking around in a search area on the ground surface. GPS navigation receivers are used to locate and log the changing positions of the EMG receiver and stationary loop transmitter.

Abstract: An embodiment of the present invention is a roadway sensor for surface installation in a hole such that a thin ceramic contact sensor may be used to measure and cross-compare fundamental physical antenna parameters of the space immediately above a roadway or bridge surface. Measurements are combined by a microprocessor to discriminate between dry pavement, water (rain), snow and ice above the sensor head. Ambient surface temperature, water depth and ice/slush conditions are determined to estimate any hydroplaning hazard and ice/antifreeze/water mixtures. The sensor comprises an antenna that exhibits a resonant frequency and an input admittance including a real term; a Maxwell bridge coupled to the antenna for detecting the resonant frequency, input admittance and real term; and a frequency sweeping oscillator for driving the antenna at a plurality of frequencies proximate in frequency to the resonant frequency.