Device for measuring moisture in substrate and health of hair
A sensor for measuring moisture content of a substrate, comprising: a coplanar waveguide; a directional coupler having a pair of generally parallel first and second strips defining a coupling gap therebetween; and a high frequency signal generator electrically coupled to said first strip and operable to couple power to said second strip with the substrate placed across said coupling gap to thereby generate a coupled power signal in said second strip having an amplitude related to moisture content of the substrate.
1. A sensor for measuring moisture content of a substrate, comprising:
(a) a signal generator operating in the VHF, UHF or microwave range, from which a signal at a chosen operating frequency is generated;
(b) a directional coupler comprising two strips, a first strip and a second strip, wherein the first strip is generally parallel to the second strip such that a coupling gap is defined therebetween, wherein the substrate to be measured is placed across the coupling gap, the first strip being electrically coupled to the signal generator; and the first strip generating an electromagnetic field across the coupling gap to the second strip,
(c) the first strip is electrically coupled to a first port of a mixer;
(d) the second strip is electrically coupled to a section of coplanar waveguide, wherein the section of coplanar waveguide is designed to give a 90 degree phase shift to the signal at the chosen operating frequency, and the coplanar waveguide is electrically coupled to a second port of the mixer;
(e) the output of the mixer is electrically coupled to a computer with a visual display capable of a user-perceptible indication of the measured moisture content of the substrate; wherein the signal generator, the coplanar waveguide, and the mixer are integrated into a printed circuit board.
2. The sensor for measuring moisture content of a substrate of claim 1 wherein the coupling gap is 0.020 inches.
3. The sensor for measuring moisture content of a substrate of claim 1 wherein the printed circuit board is a Rogers board or a FR4 type board.