DK7ZB Triple-Leg

This antenna was used at the DX-peditions by CE0Y/DK7ZB and CE2/DK7ZB in October 2010 with good results. The supporting structure is a 15-m-glassfibre mast of DX-Wire. The antenna can be used on all bands from 10-40 m.

You need 4x 7-m-wires.The lower guys are the 7-m-radial-wires of the Triple Leg, the upper guys are insulated ropes made of dyneema. The antenna is fed with a 400-Ohm-Wireman cable.

Of cause you need an symmetrical antenna tuner for this antenna. In this case the twinlead was 12 m long. See the impedance points in the tables below.

Band	Impedance at Feedpoint	with Wireman 3,20 m	with Wireman 12 m	Gain	Elevation angle
10 m	75 + j 395 Ω	41 - j 110 Ω	92 - j 426 Ω	+ 2,3 dB	9 °
12 m	256 - j 900 Ω	68 + j 314 Ω	60 - j 224 Ω	+1,46 dB	11°
15 m	2960 - j 1265 Ω	52 - j 23 Ω	235 + j 900 Ω	0 dB	12°
17 m	900 + j 1330 Ω	65 - j 180 Ω	233 + j 246 Ω	-0,5 dB	13°
20 m	154 + j 108 Ω	444 + j 445 Ω	434 + j 439 Ω	-1,2 dB	15°
30 m	60- j 31 Ω	306 + j 321 Ω	73 - j 166 Ω	-2 dB	18°
40 m	28 - j 385 Ω	16 - j 100 Ω	125 + j 970 Ω	-2,4 dB	22°

The impedances at the feedpoint show a problem at the 15-m-band (impedance to high, Voltage maximum). Therefore it is recommended to feed with Wireman-cable of 3,20 m or 12 m. With these lengths a tuner has the best conditions for matching. With 3,20 m the box with the tuner is mounted at the mast. From there a coax-cable is leading to the station. If you need a longer feeder, use 12 m to the tuner.

The SG-239 is used with great success for the feeding of the 7-m-Triple-Leg.

The input has a balun (2x5 turns PTFE-coax on FT117-77) and a choke for the 12 Volt input (10 turns wire on FT82-77).

The azimuth diagram on lambda/4 lengths is nearly like a circle (look for 30 m). If the length is greater than lambda/4 the radiation gets a figure like the diagram for 10 m.

If you need four "radials" (better for the supporting structure!) you can use that without any problems. Then you have no "Triple-Leg", it is now a "Quadruple-Leg".