Will a cone of magnetic material increase the strength of earth's magnetic field?

If it's possible to guide magnetic field lines using a shaped magnetic material(cone) and the increase in magnetic field strength is proportional to the ratio of the areas of the two ends of the cone,will a cone of magnetic material held in the air or placed on the ground increase the density or strength of earth's magnetic field? In otherwords if I had a cone of 45 degrees with a 1 inch hole on top and 10 inches at the bottom and earth' average magnetic strength is approximately .45 gauss,at the top of the cone it should measure 4.5 gauss?

• Yes, this arrangement is sometimes being used in very sensitive fluxgate magnetometers. I think I saw this arrangement in a NASA planetary magnetometer once. I will try to dig up an image for you. I think you are off by a factor of ten, by the way... $(10:1)^2=100$. – CuriousOne Apr 20 '16 at 23:11