Topband: K9AY loop -- adding additional radials?

[Peter Bertini]

Adding  four  cheap 3/8" 4-ft  TV ground rods--one  at each of  the ends of
each of the 21 foot radials-- did the trick.  The lone ground rod at the
hub was not enough.  Now have good deep nulls in all 4 quadrants.. Adding
four more radials didn't seem to improve things as much as the first set of
radials and the additional ground rods.  Now a happy camper!!