The vertical polarized 2x7m-Double-Zepp-Antenna
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The vertical Double-Zepp 2x7 m is a very simple, effective 8-Band-antenna. The end of the Dipol must be 5-10 m above the ground. My antenna had the feeding point in 13 m above the ground, the diagrams are for this mounting. Is the end to close to the ground, the pattern has a higher radiation angle. The antenna was fed with 450-Ohm-Wireman-cable. You must have an antenna-tuner for the matching of the system. I used the SG-239 for all bands from 10-80 m and about 9 m Wireman to the roof of my house. You can use a wooden pole for support or a high tree. |
| Unfortunatly the hurricane
"Kyrill" in February 2007 broke my 18 m high pine-tree with the
vertical before I could take a photo shot. All other antennas survived the
storm without any damage.
The support for the upper wire was a glassfibre windsurfing boom with 4,50 m and a 10 m long fishing rod. |
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Gain and the angle of the radiation:
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Band |
10 m |
12 m |
15 m |
17 m |
20 m |
30 m |
40 m |
80 m |
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Gain |
2,7 dBd |
2,91 dBd |
1,51 dBd |
0,38 dBd |
-0,8 dBd |
-1,51 dBd |
-2,13 dBd |
-1,85 dBd |
| Angle |
8 ° |
9 ° |
10 ° |
11 ° |
12 ° |
14 ° |
17 ° |
22 ° |
The following diagrams are for a real ground with a medium resistance, plotted with EZNEC v. 5+ from W7EL.
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10-m-Band The antenna is longer than 2x5/8-Lambda, therefore it has a second lobe with 70°. Gain: 2,7 dBd at 8° |
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12-m-Band Here is the length 2x5/8-Lambda and an excellent pattern is the result. Gain: 2,91 dBd at 9° |
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15-m-Band Gain: 1,51 dBd at 10°
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17-m-Band Gain: 0,38dBd at 11°
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20-m-Band Gain: -0,8 dBd at 12°
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30-m-Band Gain: -1,51 dBd at 14°
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40-m-Band Gain: -2,13 dBd at 17°
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80-m-Band Gain: -1,85 dBd at 22° On 80m are some losses in the Wireman-cable, because the feedpoint impedance on 3,6 MHz is very low (9 - j 1150 Ohm). But you must try it out. |
