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.

The 2+2-Element-

Duoband-Yagi

 

4,12dBd on 2m

5,4dBd on 70cm

The vertically polarized Yagi

built by  Volker, DO1SN

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

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