| Construction | 12-Ele.-28-Ohm | 13-Ele.-28-Ohm | 14-Ele-28-Ohm | 16-Ele.-28-Ohm |
| 17-Ele.-28-Ohm | 19-Ele.-28-Ohm | 21-Ele.-28-Ohm | 23-Ele.-28-Ohm | 27-Ele.-28-Ohm |
70cm-Longyagis in 28Ohm-DK7ZB-Design
Short Data of the Yagis at 432MHz
| Type | 12-El. | 13-El. | 14-El. | 16-El. | 17-El. | 19.-El. | 21-El. | 23-El. | 27-El. |
| Boom | 2,50m | 3,00m | 3,10m | 3,88m | 4,05m | 4,65m | 5,25m | 5,70m | 7,05m |
| Gain | 13,8dBd | 14,5dBd | 14,6dBd | 15,5dBd | 15,6dBd | 16,2dBd | 16,6dBd | 17,0dBd | 17,7dbd |
The elements have 10mm, 8mm or 6mm diameter, because this is very uncritical and you get the expected datas! For the tuning let the radiator 2mm longer and cut for best SWR at 432MHz. If the minimum is worse than 1.3 you should try to change the place of D1 +/-5mm. If you have a spectrum analyzer you can follow that rule: Making D1 shorter raises the resistance of the radiator, making it longer the resistance will drop down. Greater changes in the length of D1 as +/- 1mm will cause another radiator length!
I have redesigned some Yagis (12/2003) with "EZNEC", because the "cut-off"-frequency was very close to 433MHz, now the antennas have 0,05-0,1dB less gain, but the design is not so critical and the bandwidth is greater.
The 2x75-Ohm-coax-cable in the box with the N-socket for the DK7ZB-match Here with the 12mm-Radiator |
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Mounting of elements With these clamps the 8mm-elements are mounted isolated 2-3mm above the boom. The screw has 3mm and is stainless steel. The screw and the electrical contact to the boom has no influence to the length of the element. |
The parallel 75-Ohm-Cables for the DK7ZB-Match (see other Webpage!) Length Lambda/4*V V=Velocity of propagation e.g. for Full-PE (RG-59) V= 0,67 Foam-PE V=0,81-0,82, PTFE V= 0,7
Use a good cable with a good braid for high screening effectiveness! |
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The Reflector, Radiator and Director 1 with the mounting box. The cable must be mounted symmetrically between the two element-halfs! |
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Waterproof construction by Helmut, DL2MAJ |
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Assembling of the elements for a 4x23-Element-Group at OL6R
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The Radiator-Box for a 23-Ele. at OL6R |
