It’s a compromise antenna and needs a tuner like most Chameleon products
They released a SOTA antenna and I made my own
However, they work and you get Multi band operation
John ve3ips
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My guess is that they connected two RF transformers (5:1) in parallel to increase output.
I also tested two in parallel to increase output. But I’m curious why they used the capacitor in the photo.
I’d guess it’s for low-band matching.
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Dale,
That’s a good point about the impedance of the folded turn. I wondered why the wire didn’t just go through one half of the winding. The impedance is proportional to frequency so I suspect it was built on the basis of let’s try this and see if it works better at the top end.
For great VSWR across the band’s a 6 dB attenuator will give this for 1 S unit loss. Needs a heatsink.
An approximate matching device should give a better signal because it transfers more power into the antenna even if the VSWR seen at the tx is a bit higher than desired.
I think there is some truth in the saying that “(getting) a low VSWR can kill you”
73
Ron
VK3AFW
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Hi Ron,
This configuration is a conventional transformer 1t:2t ratio or 12.5 Ω / 50 Ω, the folded back 1/2 turn which is a cleverly trick to induce a stray capacitance for high frequency compensation without changing the 1t:2t to 1t:3 ratio as a folded 1/2 turn having a cancelled inductance. G8JNJ claimed the fold back turn is his own IP.
For 5 Ω / 50 Ω transformer, you would need a wide band transformer, composed of transmission lines winding and capacitors for high frequency compensation.
https://cache.nxp.com/docs/en/application-note/AN749.pdf
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