Amplifying Drakkith's response, translating a whole circuit (that is moving it without turning it) through a uniform field will produce zero emf and zero current.
The Earth's field, over a large scale, is not uniform, and if you moved your circuit fast enough over a large enough distance for the non-uniformity to show up (i.e. a distance comparable with the Earth's radius), then there would be an emf, but this is almost certainly impracticable.
What IS feasible is to rotate a coil about its diameter in the Earth's field, making connections to an external circuit by means of slip rings. This is, of course, none other than an a.c. generator (with a very weak magnetic field!).