Assuming the following: 1. Noisy, suburban neighborhood 2. 4 foot diameter loop 3. Remote tuned, with trenched coax and isolated connections at both ends. Given these parameters can someone tell me if a shielded loop or an unshielded air core loop would work best? Objective is weak signal lowfer, MW BCB, and 160 Meter DX receive antenna. 73, Les Rayburn, N1LF