| Open-sleeve principles | VHF-Duoband principles | Duoband-Yagi 6m/10m | Triband-Yagi 6m/4m/2m | Duoband-Dipol 2m/70cm | 2m/70cm 2+2/3 El. | 2m/70cm 4+5 El. | 2m/70cm 5+8 El. |
Duoband DK7ZB-Yagis 2m/70cm with 2 Elements on 2m
and 2/3-Elements on 70cm and one Feedpoint
These Yagis cover the range of 144-146MHz on 2m and 430-440MHz on 70cm.
They can be used for alle modes (FM and SSB/CW). On both bands the SWR is good across the whole band.
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The 2+2-Element- Duoband-Yagi
4,12dBd on 2m 5,4dBd on 70cm |
|
The vertically polarized Yagi built by Volker, DO1SN |
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 |
 |
|
Band |
Gain |
F/B |
3dB-angle
hor. |
3dB-angle
ver. |
|
145MHz |
4,1 dBd |
10 dB |
69,8° |
137,2° |
|
435MHz |
5,4 dBd |
11 dBd |
40,7° |
167,2° |
Lengths and Positions of the Elements, all 6mm Diameter
|
Element-Nr. |
Element |
Length |
Position |
|
1 |
Reflector
2m |
1022mm |
0mm |
|
2 |
Reflector
70cm |
322mm |
230mm |
|
3 |
Radiator
2m u. 70cm |
938mm |
370mm |
|
4 |
Open-Sleeve-Element 70cm |
318mm |
392mm |
The radiator box with the 50-Ohm-choke, 40cm RG-188 (or similar) on 16-20mm PVC-tube
The homemade holder for the boom, lightweight and inexpensive
The 2+3-Element Duoband-Yagi
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With an addional director the gain on 70cm can be increased to 6,2dBd. The SWR on 70cm is better in the range 430-438MHz. For receiving above 438MHz the antenna is good enough! So we have 2 elements on 2m and 3 elements on 70cm. The data on 2m are they same as with the 2+2-El.-Yagi.
|
|
Elements
(6mm) |
Length |
Position |
|
Reflector
2m |
1022mm |
0mm |
|
Reflector
70cm |
320mm |
230mm |
|
Radiator
2m u. 70cm |
939mm |
370mm |
|
Director
1 70cm |
323mm |
399mm |
|
Director
2 70cm |
297mm |
500mm |
