Experiment! Try a one or two turn secondary. Sometimes you have to throw the textbook and theory out the window. The original design for my 1 metre loop called for a single secondary winding, twisted about the fourth turn of a seven turn primary winding. I tried various coupling methods and eventually opted for a single turn spaced 2 cm below the fourth primary winding. Signal level became considerably reduced, but null/peak increased. My Icom R71A countered the reduced signal level. May, 1995 (Author of advice unknown)