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

70-cm-Longyagis in 28-Ohm-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

All Yagis in 28-Ohm-Technology, elements mounted with polyamid-clamps (Konni) or similar and 10, 8  or  6mm Diameter. Electrical details on the pages you see above, plots with "YO" from K6STI and "EZNEC +4"  from W7EL

The elements have 10 mm, 8 mm or 6 mm 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 432 MHz. 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 433 MHz, now the antennas have 0,05-0,1dB less gain, but the design is not so critical and the bandwidth is greater.

70-cm-EME at


with 2x17-Ele.-28-Ohm-Yagi

Antennas built by Philippe, F1DUZ

The 2x75-Ohm-coax-cable in the box with the N-socket for the DK7ZB-match

Here with the 12mm-Radiator

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!

The Reflector, Radiator and Director 1 with the mounting box. The cable must be mounted symmetrically between the two element-halfs!

Waterproof construction


Helmut, DL2MAJ

Assembling of the elements for a 4x23-Element-Group at OL6R

The Radiator-Box for a 23-Ele. at OL6R