8 Bay Antennas
If you live in the deep fringe or just want to get the most stations you can then an 8 bay may be the answer. These antennas can get quite large especially the vertical stacked version with a wide curved screen reflector.
The vertical stacked 8 bay gets it's gain by squeezing the elevation reception pattern it's advantages over a horizontal stack are better gain due to the larger capture area of the reflector screen and a better co-phase harness arrangement because the harness can be ran pretty much straight from each 4 bay to the other. The Vertical stack also has a wider azimuth beam which makes aiming easier but the tighter elevation beam makes the antenna more sensitive to elevation tilting.
The Horizontal stack is the more traditional approach used by most commercial TV antenna manufacturers, the Channel Master 4228 is a prime example of a Horizontal stacked 8 bay. These make more gain by squeezing the azimuth beam, this makes for a very selective antenna and that can be good when you want to tune out a station just off axis. The narrow beam can make aiming tricky for deep fringe stations unless a very good rotor is used. Feeding a horizontal stack can also be tricky because of the sharp angles that have to be bent into the co-phase line to get around the mounting points and frame work. I have done some testing and HERE is a link to some testing I did comparing the 2 balun combiner to the open wire feed approach.
The picture below is a 10" whisker version and uses a pair of 40" tall by 42" wide reflector curved screens this monster is a noticeable improvement over a 4 bay but can be a sail in the wind and could only be used with a very well supported mast or tower.
Below is the antenna used in the 2 balun combiner and open wire feed test. It uses 9 3/4" elements spaced 9 1/2" apart and the 4 bays are spaced 26" apart. It uses a 40" high by 56" wide reflector screen with angled inner and outer edges. The reflector is made of 2" x 4" wire fence to cut down on wind loading and the frame is made of aluminum.
Both 8 bay antennas make a noticeable improvement over a 4 bay but are really over kill for most situations. I have yet to do some head to head testing between the 2 but computer models show the vertical stack to have more gain on VHF-HI and UHF.
An 8 bay can be built from 2 M4 kits and I have a drawing of a co-phase line for the Vertical stacked version. The drawing is sized for a 10" x 9 1/2" bay spacing but could be used with others by simply shortening the section either side of the feed point equally to fit your spacing.