Re: cable thickness
 

I use SSB Aircell 5, as well as LMR400. What does that say about my IQ?

Re: cable thickness
 

Not entirely true, the thickness of a transmission antenna can increase the resonant bandwidth so a thicker dipole might have more bandwidth than a thinner dipole but this bandwidth is in relation to forward and reflected power (otherwise known as SWR measurements).

This is though totally different to bandwidth of a carrier medium like co-axial cable of which he is getting mixed up with.

Re: cable thickness
 

Ah, resonant bandwidth... I was thinking resonant frequency and baseband bandwidth.

Re: cable thickness
 

Practicalities seem to be the biggest problem with thicker elements, it's not much of a problem for VHF or UHF but to make a large increase with for example a top band dipole would be impractical, hence the use of birdcage for HF. I did play around with a prototype VHF 30-90MHz Fractal antenna a few years ago, that had a nice wide bandwidth, reasonably good efficiency and low VSWR across the band, unfortunately the design wasn't mechanically practical for the intended application.


The biggest limitation on bandwidth with coax is generally the absorbing properties of the dielectric as frequency increases. The formula to calculate the loss at a particular frequency when provided with the actual loss at a lower frequency is generally logarithmic until this point is met, then it becomes very unpredictable. The use of a foam dielectric in cables such as LDF4-50a and LDF5-50a (There are more modern types and this shows my age) allows them to be used generally at a higher frequency than the PTFE dielectric types.

Re: cable thickness
 

Ecoflex 15 inparticular which has a gas rich dielectric compound is usable up to 6GHz and there's a more recent plus version which can run up to 8GHz.

I use it on my 2m and 70cm arrays which is probably a bit of overkill but it's mechanically very nice and flexible thus easier to route and work with than hardline :)

Re: cable thickness
 

Aircell 5 is 1/3rd as thick and rated to 10Ghz.

Re: cable thickness
 

Aircell 5 is nice stuff for a short run. A bit lossy for my application as there's a pretty long run up the tower to the pre-amps so the Ecoflex 15 was the compromise between having something approaching heliax for attenuation characteristics but flexible enough to work with easily when doing installation and maintenance.

Re: cable thickness
 

Yeah, it's power handling isn't particularly high either but enough for short runs on 2-6Ghz microwave bands as you say. I have a reel of LMR400 as well. Not as good as Ecoflex but a bit cheaper but both are just too thick to run around a building without anybody noticing :p: (Bloody conservation area/listed buildings...)