Theory of the Quadlongs  4/6mQuadlongs  2mQuadlong  2m4xQuadlong  2m4xOblong  The Hentenna (2 m, 4m, 6 m) 
The 144MHzDK7ZBQuadlong and DoubleQuadlong
New DoubleQuadlong see down!
The 2mQuadlong was designed for 144,3 MHz to use it for horizontal polarisation in the CW/SSBmodes.
Stacked versions see below!
Short Data of the DK7ZBQuadlong Gain 6,5 dBd, F/B 18,5 dB 3dBangle hor. = 72°, 3dBangle ver. = 70° 
Picture right: Scheme of the Quadlong
Impedance 28 Ω , feeding with the DK7ZBMatch Dimensions for the 144MHzQuadlong: Distance LoopReflector = 300mm
Important: All lengths given from center to center! Lengths in the table below.

2x 28OhmQuadlong stacked Built by Gunter, DL2DRG 
Diameter Loop rods  Length ver  Length hor  Length Reflector 
4mm  782 mm  314 mm  1030mm (8mm) 
5 mm  785 mm  314 mm  1034 mm (5 mm) 
6 mm  787 mm  314 mm  1033 mm (8 mm) 
10 mm  797 mm  314 mm  1034 mm (10 mm) 
The stacked Version with the 25ΩQuadlong
For the stacked version the impedance of the single Quadlong was changed to 25 Ω at XX because with that impedance a clever stacking is possible. With two lengths L of 50Ωcoax 3/4 λ* V (with fullPE 2 x 103,5 cm) we have an impedance transformation to 100 Ω at XX. With both cables parallel we get 50 Ω at XX. The first 45 cm of the cable starting at XX is wound to a coaxchoke for balanced feeding of the loop. The distance between the two antennas (parts 3 and 10) is 110 cm. This feeding is described at the 2x25ΩYagis stacked (LightweightYagis). 
Gain 9,6 dBd F/B 21 dB 3dBangle hor. = 72,2° 3dBangle ver. = 30,0° The gain is 9,6 dBd with excellent radiation patterns. The 9,83 dBd in the right plots are without the stacking losses. Lengths (6mmelements): Hor. (3, 4, 9, 10) = 298 mm Ver. (1, 2, 7, 8) = 806 mm Reflectors 1029 mm, 8mmDiameter Distance RefLoop 295 mm 

The 144MHzDK7ZBDoubleQuadlong
The Quadlong can be built up with a double frame. The gain increases only 1 dB, but this antenna has a greater bandwidth than the single Quadlong. Feeding with the DK7ZBchoke, the same as for the Quadlong. 
Data of the DK7ZBDoubleQuadlong: Impedance 28 Ohm Gain 7,5 dBd F/B 23 dB 3dBangles 72° hor 55° ver 
The gain is 0,7 dB higher than the well known "DoubleQuad" by DL7KM and DJ9HO. The mechanical construction is much easier! 
The lengths ot the elements, distance center to center of the tubes
Ref.Length  1050 mm (10 mm) 
D (RefLoop)  320 mm 
3, 4, 6 (hor)  312 mm (10 mm) 
1, 2, 5, 7 (ver)  725 mm (10 mm) 
New DoubleQuadlong with higher gain and 50 Ohm impedance
With feeding in the
lowest section (not in the middle) and a greater ratio between the
horizontal and vertical parts we get new characteristics: Impedance 50 Ohm Gain 7,8 dBd 
All tubes 8 x 1 mm Aluminium