Inductive coupler

#This application is related in subject matter to application Ser. No. 71,634, filed concurrently herewith and assigned to the same assignee as the present invention.

#1. Field of the Invention

#The invention in general relates to signal and/or power coupling devices, and more particularly to one of the inductive coupler variety.

#FIG. 1 is a view, partially in section, of a prior art face-to-face inductive coupler;

#FIG. 2 are curves illustrating the performance of the coupler of FIG. 1;

#FIG. 3 is a view of another prior art inductive coupler;

#Referring now to FIG. 1, there is shown a typical prior art face-to-face inductive coupler. The coupler 10 is comprised of two housing parts 12 and 13 each including a respective C-shaped core member 15 and 16 having respective windings 18 and 19. Stainless steel cover plates 21 and 22 protect the core members from the ambient medium such as an underwater environment.

#Windings 18 and 19 are electrically connected to respective cables 24 and 25 which in one typical use convey data or information signals. Such couplers are extremely sensitive to variations in frequency response due to relative separation of the two mating portions 12 and 13. For example, in FIG. 2, curve 30 illustrates a typical frequency response with no gap between the mated portions. Curve 31 illustrates the degraded response if the housing parts are separated by a distance of 0.031 inch (0.0787 cm). The curves illustrate that at 100 kilohertz (kHz), there is an approximately 2 dB reduction in response, however, at the lower frequencies, the difference is significantly greater.

#Another type of prior art inductive coupler which has been proposed for use in an explosive atmosphere is illustrated in FIG. 3 in cross-section and includes an outer cylindrical member 34 having radially inwardly-extending flanges 35 and 36 at each end whereby a winding 38 is fixed in the interior of the cylinder. The other core member 40 includes two end discs 41 and 42 joined by a cylindrical center limb 43, the arrangement carrying winding 45.