Vertical 2x7m-Double-Zepp |
The Battle-Creek-Special |
The vertical polarized 2x7m-Double-Zepp-Antenna
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The vertical Double-Zepp 2x7m is a very simple, effective 8-Band-antenna. The end of the Dipol must be 5-10m above the ground. My antenna had the feeding point in 13m 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 10-80m and about 9m 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 18m 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 4,50m and a 10m long fishing rod. |
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Gain and the angle of the radiation:
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Band |
10m |
12m |
15m |
17m |
20m |
30m |
40m |
80m |
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Gain |
2,7dBd |
2,91dBd |
1,51dBd |
0,38dBd |
-0,80dBd |
-1,51dBd |
-2,13dBd |
-1,85dBd |
| 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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10m-Band The antenna is longer than 2x5/8-Lambda, therefore it has a second lobe with 70°. Gain: 2,7dBd at 8° |
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12m-Band Here is the length 2x5/8-Lambda and an excellent pattern is the result. Gain: 2,91dBd at 9° |
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15m-Band Gain: 1,51dBd at 10°
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17m-Band Gain: 0,38dBd at 11°
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20m-Band Gain: -0,8dBd at 12°
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30m-Band Gain: -1,51dBd at 14°
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40m-Band Gain: -2,13dBd at 17°
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80m-Band Gain: -1,85dBd 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. |
