Hello All.
                    The DDRR Antenna
The DDRR (Directional-discontinuity Ring Radiator), vertically polarized 
antenna....The DDRR illustration in the 1967 Radio Amateurs Handbook shows 
two wire circles, the top wire being an open circle and the bottom as a 
closed circle.
One end of the open circle attaches to the bottom circle as H in the formula. 
The feedpoint is X distance from the open wire attachment, fed with RG-8/u, 
shield to bottom circle. The illustration also shows a grounded point on the 
bottom circle, which means it is attached or laid on the ground. Not required 
as the antenna we made was grounded by the vehicle body.
Length (circumference) around the top (open) or bottom (closed) wire, in 
feet, L = 252/f(Mhz) (IE; 64.7 feet for 3.9Mhz).Height, or spacing between 
the two elements; H=8.5/f(Mhz) (IE; 2.2feet at 3.9Mhz).The feed point 
distance, X, is given approximately by X = 28/f(Mhz).(IE; 7.2 feet at 
9Mhz.)
My notes from the experimenting we did (c1969) on 11 meters shows the wire 
lengths L to be 9' 3 5/8", the spacing H to be 3 3/4" and the feedpoint X at 
12 3/8"..the experiment was figured for 27.1Mhz...:)
This antenna was mounted in the back of an El Camino.  It performed very 
well, although it had a high wind resistance and needed to be guyed so it 
wouldn't blow over at 65mph...This kind of antenna experimenting is what 
brought me to Amateur Radio in 1970...now that I could work VHF and UHF, the 
antennas I built were much easier to handle...And you guys thought CB'ers 
were nothing but skip talking truckers and hillbillies...
Anybody interested in building UHF stacked Quagi's, let me know..
... Roy's Radiator Shop, Best place in town to take a leak...
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