If you go here you can see the three antennas I have on my rooftop in Loves Park.http://www.avsforum.com/avs-vb/attac...3&d=1309136914
Here is a long convoluted post about the simultaneous use of all 3 of them. This message complexity is due to the sometimes complex situations brought about by using 2-3 antennas at once -- so please bear with me.
The top one does Madison with most stations received 24/7, esp. ch 27 which now has 1000 Kw of ERP as I recall. Most of the other Madison channels have between 171 Kw and 603 Kw according to a page I read.
But, when I hook up a third antenna, either the Yagi pointed at ch 13 (Rockford) or the 4 bow-tie pointed at channels 23 and 39 (Rockford), channels such as 21, 03 (50) and 45 -- all in Madison -- disappear. However Channel 27 (Madison) with its highest power still remains.
Is this reception problem due to an interaction between various frequencies radiated by certain antenna combos or is it just a simple signal strength reduction because of the need for a 2nd antenna combining device in the mix? Channels 13 and those in Madison are joined by a combiner (UHF and VHF) with the third VHF (channels 23 and 39) joined by a splitter placed in backwards. All of this results in only one cable going to the TV set.
So, is the problem reduced signal strength because of a 2nd signal management element in the mix or an interaction between a 3rd antenna and the other two? I even changed the phasing of one of the DB4s to remove the possibility that its received signals were interfering with the other DB4.
Next week I will remove both the Yagi and DB4 antennas for Rockford and replace them with one combo antenna (Antennacraft HBU22) that does both VHF and UHF. This should provide reception on all local and Madison channels and permit their received signals to be combined down to only one lead to the TV with only a backwards splitter to join Madison channels to the local channels. The combo antenna supposedly will replace the use of one combining element and make available reception of all Madison and Rockford channels with the use of only one combining device, not two as previous. Is this true?