Re: EFHW from ARRL


Paul Christensen
 

>”How does that compare to the coax losses you would expect from a dipole?”

 

And I thought I was done posting.  Here goes…

 

I don’t use coax on my multiband dipoles.  Either 400 or 600-ohm homemade open-feeder lines are used with 24-inch spacing between Delrin spreaders.  These lines are used at my home QTH and also for portable and camping operation.  KN5L’s loss data for these lines is included in SimSmith.  Total loss can be reasonably computed in SimSmith including tuner loss with appropriate L and C Q values.

 

For camping, a 40m-10m antenna and 400-ohm line roll up nicely into a compact package.  For support – give me one tree branch.  That’s all that’s required to launch a low-loss inverted-vee configuration through a branch where the maximum current point (the vee’s center) is typically up 2x higher than that of a EFHW that uses an identical-height tall support at the far end and with the near end at ground level, near the transceiver.  With either configuration, a launch to a tall support or a collapsible pole is required.  As such, that effort is mostly a wash.

 

The Tuner.  I have two low-loss, high-Q link-coupled tuners that can be configured in a series or parallel output configuration.  Both are lightweight open designs.  Any oddities at the input end of the line can be managed by either adding or subtracting a small amount of open feeder line.   

 

Rain or shine, it doesn’t matter.  The antenna system is tuned for zero reactance and matched to 50+j0 inside the tent.  Moreover, rain droplets don’t collect on the line as it does with windowed line.  SWR is stable wet or dry.

 

My goal is have an efficient antenna system to give QRP and QRPp operation the best possible advantage.  That’s why I don’t need, nor want an EFHW.  

 

Paul, W9AC

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