Triband Antenna 6M/2M/70CM

V

VK3ZNA

Guest
Has anyone built a TriBand antenna for the 6M/2M/70CM band?
My first thought was to maybe try a J Pole but then I've spotted this one...





The IC-706 covers the HF bands and the 6M-70cm bands so a suitable non HF antenna is needed.
Does anyone have a recommended design?



It should work provided that the interconnections are wires. I tried using RG213 and it didn't work, I used actual lengths and reduced to compensate for velocity factor. My next attempt is to use LDF5/50 lengths with the wires. I have a few short lengths of LDF5 to try it out. LDF5 will fit in 23mm conduit.
Geoff VK3ZNA
 
V

VK3ZNA

Guest
Hi Ray, It worked as a high gain single band antenna, as per the K5FRC article.

Regards
Geoff
 
V

VK3YNV

Guest
Hi Geoff,

Still trying to get my head around how a coaxial co-linear works, best I can figure is the half wave sections reverse the phasing so that each half wave section radiates in phase. That means the coax braid becomes the radiator in each alternate section. I'm thinking that the first quarter wave section is providing the matching to the first end-fed half wave? The other half of the quarter wave (ground side) is where you put the balun?

Finally stick a quarter wave on top, just to eliminate corona discharge? ( half joking )

Regards
Ray
 
V

VK3YNV

Guest
Looking at the numbers for the Triband coaxial Denys posted.

On 2M it's 1/4,1/2,1/2,1/2,1/4 Which is pretty much the traditional coaxial co-linear.
On 70cm it's 1 1/4, 1 1/2, 1 1/2, 1 1/2, 1 1/4. So if you subtract the whole wavelengths, the phasing is the same as the 2M array.

On 6M it's a bit problematic, none of the cross over points are phase reversal points, so no gain from phase re-inforcement, however the overall length is close to (but not exactly) a 3/4 wave, so ignoring the phasing, it's probably acting like a 1/2 wave over a 1/4 wave. But I'm guessing.

Regards
Ray
 
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