Tribander 14-21-28

[sm7vzx]

I made simulation on 5m long boom...it seems that radiator 20m and sleeve 10m are too close and very small change of distance between the affect the resonance on 10m... any chance for improvement...

Element Ф12 Ф16 Ф20 Ф25 Ф20 Ф16 Ф12 Spacing

1 1,71 1,25 1,25 2,50 1,25 1,25 1,71 0,0 R 20m
2 1,10 1,25 2,50 0 0 1,25 1,10 0,45 R 15m
3 1,41 2,50 0 0 0 0 1,41 0,95 R 10m
4 1,01 1,25 2,50 0 0 1,25 1,01 3,10 Z 15m
5 1,39 1,25 1,25 2,50 1,25 1,25 1,39 3,24 Z 20m
6 1,38 250 0 0 0 0 0 3,38 Z 10m
7 0,78 1,25 2,50 0 0 1,25 0,78 4,29 D 15m
8 1,285 250 0 0 0 0 1,285 4,55 D 10m


Elements are isolated from the boom, feeding at element number 5. Gap at element number 5 (Z20) is 10mm.`

[sm7vzx]

Re: Tribander 14-21-28

http://www.qsl.net/7s7v/antennas/2-3...(14-21-28mhz)/

[IK2XSL]

Re: Tribander 14-21-28

I made simulation on 5m long boom...it seems that radiator 20m and sleeve 10m are too close and very small change of distance between the affect the resonance on 10m... any chance for improvement...

Element Ф12 Ф16 Ф20 Ф25 Ф20 Ф16 Ф12 Spacing

1 1,71 1,25 1,25 2,50 1,25 1,25 1,71 0,0 R 20m
2 1,10 1,25 2,50 0 0 1,25 1,10 0,45 R 15m
3 1,41 2,50 0 0 0 0 1,41 0,95 R 10m
4 1,01 1,25 2,50 0 0 1,25 1,01 3,10 Z 15m
5 1,39 1,25 1,25 2,50 1,25 1,25 1,39 3,24 Z 20m
6 1,38 250 0 0 0 0 0 3,38 Z 10m
7 0,78 1,25 2,50 0 0 1,25 0,78 4,29 D 15m
8 1,285 250 0 0 0 0 1,285 4,55 D 10m


Elements are isolated from the boom, feeding at element number 5. Gap at element number 5 (Z20) is 10mm.`

Hi, nice project.
What about overall performance on air?
Is f/b as expected?
Weight?
Marco - IK2XSL.

[sm7vzx]

Re: Tribander 14-21-28

Hello Marco,
The performance on the air is OK, match to simulation. The only week point is 28MHz, very sensitive to wind blowing and not covering whole 28MHz band with accepting SWR...probably due to close spacing between Z20 and Z10. Small changes in distance between these elements change SWR.
The weight is ca 15kg with diameter of tubes.

73' Samir, sm7vzx

[ik2bcp]

Re: Tribander 14-21-28

The only week point is 28MHz, very sensitive to wind blowing and not covering whole 28MHz band with accepting SWR...probably due to close spacing between Z20 and Z10. Small changes in distance between these elements change SWR.

Hi Samir,
have you tried to add another sleeve for 10m?
Probably, with two sleeves of different lengths, you could have a broader bandwidth.
HyGain used this solution to its Explore14, naming it "Parasleeve".
73 de Guido, ik2bcp

[IK2XSL]

Re: Tribander 14-21-28

Hello Marco,
The performance on the air is OK, match to simulation. The only week point is 28MHz, very sensitive to wind blowing and not covering whole 28MHz band with accepting SWR...probably due to close spacing between Z20 and Z10. Small changes in distance between these elements change SWR.
The weight is ca 15kg with diameter of tubes.

73' Samir, sm7vzx

Hi Samir, you should try to connect some insulators between the 20m driver and the sleeve for 15m and 10m, to keep them always at the same distance when wind tries to move them.
Marco - IK2XSL.