On a mobile antenna installation I try to have 24" between mounts, I was told this by a Motorola FTR 30 Years ago.
As far as mounting on a tower I would think that 4 to 5 Ft would be a good start. That seems to be what I have seen on managed roof top antenna grid installations. On the AON building in Chicago the grid system the antennas are mounted 10Ft apart on the roof top. Paul R. Dumdie Jr. "73" W9DWP/R IRLP-NODE-4455 443.025/2A 145.270/1B/1Z/NAC-293 ARC-Radio-8 KCARES KCAPS HERD546 EX WB9QWZ WQGG738-462.725 AAR5CU/T www.riflesandradios.com www.theherd.com
