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[TowerTalk] Shortened Dipole on 160M

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Subject: [TowerTalk] Shortened Dipole on 160M
From: (
Date: Wed, 19 Sep 2001 04:29:48 EDT
<< In a message dated 9/18/01 6:02:31 PM Pacific Daylight Time, writes:<< 
  Frank, et al
  Guess I missed the original post and the subsequent ones, but FWIW, I've
  tried hundreds of antennas over the years
  for all bands 70cm-160m, many of them on 160m.
  Specifcally for 160m,  in no real order:
  Alpha-Delta DX-A twin sloper
  Low dipole (apex @ 48')
  Inverted Vee (variation of same)
  Carolina Windom 160
  Full wave loop (rectangle) (not horizontal loop, but perpendicular to the
  Earth) Shuntfeeding a 48' Delhi tower (with 20' mast & LOTS of antennas 
 on top) 1/4-WL inverted L wire (top 'corner' @ 50')
  5/16th-WL Inverted L wire with series cap
       The last antenna BAR none kicked the others butts BIG TIME.
   I strung 170' of insulated #12AWG as an inverted L  over some tall Poplar
  trees in my yard, with a large series air variable ~800pF and it really
  works well. I have about 30-some full length 1/4wl radials)
  It ain't no 4-square but it is amazing.  I rarely get on 160m anymore but in
  a year and a half or so I worked 150+ countries
  on 160m running either 100w or 1kW.(usually the latter)
  I almost always had 2 or 3 antennas on the go at any one time so always did
  the "A-B" comparison thing.
   I can assure you, the 5/16th inv-L cracked the pileups 8 or 9 times out of
  10, the first call.  Now, I live in a swamp so have great soil for 160m but
  this antenna REALLY works.
  Save yourself some time (AKA blood/sweat/tears) and install an inverted L.
   1000' unterminated BEV for RX @ times
   Mike VE9AA
  Michael, Coreen & Corey Smith
  (VE9AA,  VE9AAA & Baby-VE9)
  271 Smith Rd
  Waterville, NB
  E2V 3V6
  Canada >>

Mike: This is a very good report.  The L has been a very good antenna even 
back in the 30's.  I started a trend of making it longer than a 1/4 wave and 
adding a variable BC variable in series to tune out the XL from being too 
long.  It also raises the Rr closer to 50 ohms or even above for 70 ohms 
coax.  Another concept is to make it long enought to a "Create 160 Ohm" Rr 
feedpoint and match it with 90 ohm coax.  This improves the ratio of Rr/RLoss 
for the same radial system and that is always beneficial.  The vacuum 
variable is nice but is a problem to adjust from the shack.  The 1000 pf BC 
variable does its thing in less than 180 degress across the whole 160 or 80m 
band.  One suggestion is to adjust the length and orientation of the L so 
that 50 ohms is obtained say at 3.6 MHz.  This way the Rr at 3.5 MHz is less 
than 50 and above 3.6 MHz it's above 50 rather than 50 ohms at 3.5 MHz   The 
idea is to get the best average SWR curve from 3.5-4 MHz or 1.8-2 MHz or the 
range of frequency you will use.  This procedures should be obvious but there 
are still some that can't grasp the idea. 

I've had great success with the horizontal quad loop for local and a fair 
ways out with no skip zone like a vertical.  I've worked some 4000 mile DX on 
75 SSB also.  A quad loop say .15 WL high uses the ground as a reflector 
giving it a "kick start" up up up and away not even passing over ground 
before it hits the receiving antenna.  I call it the "Slam Dunk Antenna."  It 
has a very efficient path.

I use a couple of ways to load a 80M quad loop 20' high on 160 (or a 40M loop 
on 80M) with a way to get low SWR (50 ohms) over the entire 160 or 80M band 
using 600 ohm open wire line with virtually no feedline loss.  I loaded a 40M 
loop on 160M one time (15 KHz bandwidth) with 35W and beat a local with a 
KW-1 on AM using an L in signal to another AM station 25 miles away.  High 
angle does far more than most are aware of throughout the entire 11 year 
cycle and over 24 hours.  I consider the horizontal loop a must for every 

Your having 2 to 3 different antennas up for a A/B/C test is a great idea 
that few do.  I've worn out a couple coax switches over the years.  k7gco     

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