Having used a full size 1/4 wave ground mounted (2) verticals w/spacing to achieve ( black figure 3) pattern for 80/160m(barracuda pattern)
One must remember achieving directivity, in those patterns creates equall or Greater Nulls opposite those greater peak directions. Thus even with no delay shifts, the null created at 90 degs to antenna is very deep.
I remember experimenting with "Dual Phased" antennas on a pick-up I had. I also set-up the same for couple other operators. The key to remember was I never got max signal forward/rear, the max always resembled the pattern on lower left figure Freecell displayed.
The corners were always stronger than straight front/rear, I always attributed this to the pattern distortion created by the less than quarter wave spacing on a pick-up. Hard to get spacing like 104 inches apart (in the clear) as any cab, body parts would cause pattern distortion.
Thus you spent a great deal of time trying to achieve the front/rear pattern, only to find out you still had one direction seemed to prove better than all the rest. I always found one of the "rear" corners were the "Hot" spots.
Trying to create this(strongest front/rear) pattern on Semi rig would be almost impossible in the truest sense.
VHF/UHF frequencies were better suited for that front/rear pattern than any frequency below say 50 MHz
So my worthless 2 cents.
All the Best
Gary
