[TowerTalk] 160-m Inverted L or Sloper?

[ersmar@comcast.net]

Rich/K9OM:

     I've had all three antenna designs mentioned in this thread: Inverted L and shunt-fed tower on 160M and an 80M sloper wire off my 64-foot tower.  In my case they all worked in that they presented a good match to my 50 Ohm coax feedlines and I have been able to work just about anything I can hear on these bands, which is not much.  (Gotta work on that K9AY array.)

     In terms of complexity of construction, the sloper is by far the easiest to install mechanically.  Next comes the L then the shunt-feed system; both of these require good RF radial fields.  (I'm not sure whether a sloper will benefit from the presence of an RF radial field; we've been told here that it will.)

     Cost-wise they line up the same way: Sloper cheapest (one wire) to inv L (one wire plus radials) to shunt-feed the most costly (Gamma cap and radial wires needed here.)  

     Are you limited by time, space and/or money to install just one permanent solution?  If not, try 'em all.  At one point I had my shunt-feed and Inverted L operating as A/B antennas on 160M.  This arrangement led me to conclude that my tower was about 5-10 dB better TX and RX than my L.  FWIW.  YMWV.

     Let us know which way you decide to go and why.

73 de
Gene Smar  AD3F



> For 160 meters, 1/4 wl is 128 feet, six inches, give or take.
> 
> At 60 feet high, that 128.5 foot hypoteneuse will create a triangle 114
> feet-ish along the ground, which will make it virtually indistinguishable
> from one-half of a horizontal dipole that starts at a clearly insufficient
> height off ground for DX and tapers to near-zero elevation.
> 
> Couple that with the fact that even under the best circumstances (a tower
> height allowing for at the very least a 45-degree slope), the half-sloper is
> a highly unpredictable antenna design, and I don't like the sloper's
> chances. Like VA5DX says, the sloper may work or it may not, but I think
> your chances are better on 80 given the 60-foot tower height.
> 
> Since you are contemplating an inverted-L, you obviously have no aversion to
> radials. That may be the way to go, but the inverted-L appears to work best
> when cut for at least 5/8-wl total length. Some say 3/4-wl.
> 
> A few options that might work even better: Shunt-feed the tower. This will
> take experimentation to get the drop wire height and spacing to tower
> correct as well as the capacitive network needed at the bottom. If you can
> add a loading coil and a whip at the top (Minooka), even better. Radials,
> radials, radials.
> 
> Build an 80-meter inverted vee with twinlead or open wire for a feedline to
> the ground. Short the feedline at the ground and feed it just like a
> vertical. Over radials. This has the advantage of being able to be
> constructed to serve as both an 80-meter vee AND a 160-meter top-load
> vertical if you wish and gets the outside ends of the antenna off the
> ground. You can also use coax.
> 
> Build a 160-meter inverted vee but with no feedline and the two legs of the
> antenna shorted to each other where the feedline normally would go. Feed it
> at one end (at the ground) with radials under the tower, under the feedpoint
> and under the far end, with one wire running as a radial between the coax
> sheild and the far end of the antenna. This is DeMaw's half loop (also
> modelled successfully by Belrose in a half-delta configuration.)
> 
> I don't mean to demean the sloper. W8JI says it's an unpredictable design
> and I have no reason not to believe him, but it also has been shown to work.
> 
> But I just think it won't be high enough in this application.
> 
> 73, kelly
> ve4xt
> 
> 
> 
> 
> ----- Original Message ----- 
> From: <RLVZ at aol.com>
> To: <towertalk at contesting.com>
> Sent: Sunday, November 13, 2005 7:04 PM
> Subject: [TowerTalk] 160-m Inverted L or Sloper?
> 
> 
> > Hi guys,
> >
> > For 160-meter DX work, and a tower height of only 60', would you
> recommend
> > an Inverted L or a 1/4 wave Sloper?
> >
> > Thanks!
> > K9OM
> > _______________________________________________
> >
> > See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
> questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
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> _______________________________________________
> 
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather 
> Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions 
> and ask for Sherman, W2FLA.
> 
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