[TenTec] OT: Openwire/Window Line and Bad Wx

[Steve Hunt]

ARRL literature has consistently underestimated the losses of 
ladderline. For example, the matched losses quoted in the ARRL Antenna 
Book - at least up to the 21st edition - are about one half the figure 
you arrive at from a basic analysis of the copper losses.

The QST article "The lure of ladderline" also grossly underestimates the 
ladderline losses. At 3.8MHz a 66ft dipole at a height of 30ft over 
average ground has a feedpoint impedance of around 11-j964 Ohms; that 
would produce a loss of 8.9dB in 50ft of Wireman 551 ladderline or 6.1dB 
in the superior 554, compared with 1.37dB quoted in the article. Even 
600 Ohm open-wire line would have a loss of over 2dB with that load.

Don't get me wrong, I like balanced transmission lines; but be very wary 
about any of the loss figures quoted by ARRL.

If you do the basic maths on the copper losses, you'll arrive at a 
matched loss figure almost exactly twice the ARRL figure. Call me 
cynical but: did ARRL forget that there are two conductors and failed to 
multiply by two?

Steve G3TXQ