W9JEF
02-26-2014, 01:04 PM
Main skywire is crossed inverted "V" dipoles (69' each leg),
NE to SW, and NW to SE, up 48 feet, drooping to about 27 feet at ends.
Fed with four-wire 14-gauge insulated solid copper open line.
The antenna proper:
Each of the 4 legs is a continuation of the same feeder --no splices.
Lightweight doughnut-shaped spreaders for the 4 wires cut from
the bottoms of those large (non-biodegradable) plastic juice bottles.
The 4-wire apex is supported by 13 feet of 2-inch PVC
mounted at the top of a 36 foot steel tower. On the way down,
the 4-wire feedline is spaced about 3 feet from the tower.
Depending on the preferred directivity, either dipole can be resonated
at any frequency on all HF bands. (Using the dipoles, grounding or shorting
the unused dipole feedline has no discernible effect on SWR)
Tying the four wires together, feeding against the powerline neutral
and radials as a top-loaded cage vertical for DX on 160, 80 and 40.
Practical configurations of the four wires on all HF bands,
provides a choice of 2 dipoles, 2 bow ties, 4 vee beams,
2 turnstiles (cw+ccw), and an umbrella vertical.
Vertical wire hanging off the end of the NW insulator
(coax-fed for 30m) brings the total to 12.
Thirteen ham antennas here altogether,
counting the 50 foot TV tower & 30m vertical
(fed with quarter-wave skirt). From the shack,
it's 90 feet of open line, link-coupled at both ends.
For receiving under adverse condx, I sometimes use a 540 foot
unterminated Beverage strung into a wooded area, aimed northeast,
toward Europe (with New Zealand off the back). It also has received
the experimental stations around 500KHz --I get nothing but noise
from the big flat top on that band (600m).
BUT WAIT, THERE'S MORE!
On 80, all 4 wires can be fed in QUADRATURE (90 degree phasing)
as a CROSSED-DIPOLE NVIS TURNSTILE ANTENNA, with "wiseness"
-- clock (right-hand), or counter-clock (left-hand) -- selected by
reversing the polarity of either of the dipoles.
The main antenna tuner is link-coupled (with plug-in coils for 160 through 10).
On 80, it matches either of the crossed dipoles to 53 ohms. For quadrature feed,
there's a separate tuner, identical, except that its link is designed to match
either dipole to 106 ohms.
Meanwhile, the main tuner's 53 ohm link is fed thru a quarter-wave section
of 75 ohm coax. (RG-11's velocity factor is 66% -- 42 feet for 80.)
This length of coax not only delays the signal by 90 electrical degrees,
it also transforms the 53 ohm link to 106 ohms, which, in parallel with
the tuner whose link sees 106 ohms, presents a 53 ohm match. :)
An auxiliary T/R relay automatically reverses polarity on one of the tuners' coupling links,
allowing pre-selected rotation sense, independently for receive and transmit.
When conditions are favorable, I sometimes, believe-it-or-not, get up to 3 S-units
better signal reports transmitting with RIGHT-handed (clockwise)rotation,
and usually receive stations equally better on LEFT-handed (counter-clock).
(I know what you're thinking -- I couldn't believe it either, so I have, more than once,
checked common point SWR, and continuity of the link & relay circuit in both modes.
Independent switching of left/right-handedness on both receive and transmit
is a good idea. Sometimes on 75, especially when the band is changing,
the opposite rotations will show up to a 20 db or more difference.
Counter-intuitive as it may seem, I invariably receive the better signal report
when transmitting on the opposite rotation sense of better reception;
as, upon reflection, the ionosphere reverses the rotation.
I know you are skeptical.
So try it for yourself and I guarantee you'll be a believer.
Don't have room for two full-sized crossed 80 m dipoles?
Get as much wire as you can into 4 identical inverted vee legs,
and resonate the balanced system (including open-wire feedline)
with the matching networks. Bends are okay, as long as all 4 wires
bend in the same way.
Link-coupled tuners will provide the best balance,
and make the rotation sense easier to switch
automatically from transmit to receive.
I use a 12 volt Radio Shack relay with 10 amp contacts
to reverse polarity on one of the links.
Another reason for 4-wire OPEN LINE is its extremely low loss compared to coax,
especially on the higher frequencies (higher SWR). With proper matching,
this antenna is useful in different configurations on ALL BANDS.
On 40, 2-half waves in-phase. For higher bands, Vee beams in four directions.
For single-band turnstile mode, you could probably use 2 coax feedlines
with baluns at the dipole midpoints, and switch polarity through a toriod transformer.
Further reading:
Eric, KL7AJ has some excellent info at:
http://forums.qrz.com/showthread.php?p=1427573
For more insight on what can often be 3 db advantage
(like doubling your power) transmitting clockwise
and receiving counterclock (or sometimes visa-versa),
this Glossary of Terms could be instructive:
http://www.haarp.alaska.edu/haarp/glos.html
Eric's article explains the "X's and O's"
beginning on page 33 of December, 2010 QST.
With plans for a 15MHz turnstile (for WWV/WWVH)
you can put up to test this "revolutionary" antenna for yourself.
Also, for 30 meters (besides the 3/2 wave vee option in 4 directions),
there's a coax-fed 27 foot wire vertical hung off the end insulator
of the northwest leg of the turnstile(with a matching network near the bottom).
Since August, 2012, we have had a self-supported 50-foot triangular
galvanized steel tower bracketed to a tool shed about 60 feet behind the house.
Atop, is an old (amplified) ChannelMaster VHF/UHF TV antenna aimed at Tulsa.
There are now 6 elevated radials cut for the 30 meter band fanning out from the 6-foot level. Connected between this counterpoise and a 6-wire quarter-wave skirt,
is the output of a link-coupled tuner fed with about 90 feet of open line
by the balanced (link coupled) tuner in the shack. I guess you'd call it
a half-wave shunt-fed vertical ground plane. WWV (my 'beacon')
and other stateside stations are stronger the wire vertical .
But on WWVH and DX, the half-wave vertical is the better of the 2.
73 es dx,
. . .Jim
P.S. Details on my old 75 m extended double Zepp,
rigs past and present, and more:
http://www.hamqth.com/w9jef
NE to SW, and NW to SE, up 48 feet, drooping to about 27 feet at ends.
Fed with four-wire 14-gauge insulated solid copper open line.
The antenna proper:
Each of the 4 legs is a continuation of the same feeder --no splices.
Lightweight doughnut-shaped spreaders for the 4 wires cut from
the bottoms of those large (non-biodegradable) plastic juice bottles.
The 4-wire apex is supported by 13 feet of 2-inch PVC
mounted at the top of a 36 foot steel tower. On the way down,
the 4-wire feedline is spaced about 3 feet from the tower.
Depending on the preferred directivity, either dipole can be resonated
at any frequency on all HF bands. (Using the dipoles, grounding or shorting
the unused dipole feedline has no discernible effect on SWR)
Tying the four wires together, feeding against the powerline neutral
and radials as a top-loaded cage vertical for DX on 160, 80 and 40.
Practical configurations of the four wires on all HF bands,
provides a choice of 2 dipoles, 2 bow ties, 4 vee beams,
2 turnstiles (cw+ccw), and an umbrella vertical.
Vertical wire hanging off the end of the NW insulator
(coax-fed for 30m) brings the total to 12.
Thirteen ham antennas here altogether,
counting the 50 foot TV tower & 30m vertical
(fed with quarter-wave skirt). From the shack,
it's 90 feet of open line, link-coupled at both ends.
For receiving under adverse condx, I sometimes use a 540 foot
unterminated Beverage strung into a wooded area, aimed northeast,
toward Europe (with New Zealand off the back). It also has received
the experimental stations around 500KHz --I get nothing but noise
from the big flat top on that band (600m).
BUT WAIT, THERE'S MORE!
On 80, all 4 wires can be fed in QUADRATURE (90 degree phasing)
as a CROSSED-DIPOLE NVIS TURNSTILE ANTENNA, with "wiseness"
-- clock (right-hand), or counter-clock (left-hand) -- selected by
reversing the polarity of either of the dipoles.
The main antenna tuner is link-coupled (with plug-in coils for 160 through 10).
On 80, it matches either of the crossed dipoles to 53 ohms. For quadrature feed,
there's a separate tuner, identical, except that its link is designed to match
either dipole to 106 ohms.
Meanwhile, the main tuner's 53 ohm link is fed thru a quarter-wave section
of 75 ohm coax. (RG-11's velocity factor is 66% -- 42 feet for 80.)
This length of coax not only delays the signal by 90 electrical degrees,
it also transforms the 53 ohm link to 106 ohms, which, in parallel with
the tuner whose link sees 106 ohms, presents a 53 ohm match. :)
An auxiliary T/R relay automatically reverses polarity on one of the tuners' coupling links,
allowing pre-selected rotation sense, independently for receive and transmit.
When conditions are favorable, I sometimes, believe-it-or-not, get up to 3 S-units
better signal reports transmitting with RIGHT-handed (clockwise)rotation,
and usually receive stations equally better on LEFT-handed (counter-clock).
(I know what you're thinking -- I couldn't believe it either, so I have, more than once,
checked common point SWR, and continuity of the link & relay circuit in both modes.
Independent switching of left/right-handedness on both receive and transmit
is a good idea. Sometimes on 75, especially when the band is changing,
the opposite rotations will show up to a 20 db or more difference.
Counter-intuitive as it may seem, I invariably receive the better signal report
when transmitting on the opposite rotation sense of better reception;
as, upon reflection, the ionosphere reverses the rotation.
I know you are skeptical.
So try it for yourself and I guarantee you'll be a believer.
Don't have room for two full-sized crossed 80 m dipoles?
Get as much wire as you can into 4 identical inverted vee legs,
and resonate the balanced system (including open-wire feedline)
with the matching networks. Bends are okay, as long as all 4 wires
bend in the same way.
Link-coupled tuners will provide the best balance,
and make the rotation sense easier to switch
automatically from transmit to receive.
I use a 12 volt Radio Shack relay with 10 amp contacts
to reverse polarity on one of the links.
Another reason for 4-wire OPEN LINE is its extremely low loss compared to coax,
especially on the higher frequencies (higher SWR). With proper matching,
this antenna is useful in different configurations on ALL BANDS.
On 40, 2-half waves in-phase. For higher bands, Vee beams in four directions.
For single-band turnstile mode, you could probably use 2 coax feedlines
with baluns at the dipole midpoints, and switch polarity through a toriod transformer.
Further reading:
Eric, KL7AJ has some excellent info at:
http://forums.qrz.com/showthread.php?p=1427573
For more insight on what can often be 3 db advantage
(like doubling your power) transmitting clockwise
and receiving counterclock (or sometimes visa-versa),
this Glossary of Terms could be instructive:
http://www.haarp.alaska.edu/haarp/glos.html
Eric's article explains the "X's and O's"
beginning on page 33 of December, 2010 QST.
With plans for a 15MHz turnstile (for WWV/WWVH)
you can put up to test this "revolutionary" antenna for yourself.
Also, for 30 meters (besides the 3/2 wave vee option in 4 directions),
there's a coax-fed 27 foot wire vertical hung off the end insulator
of the northwest leg of the turnstile(with a matching network near the bottom).
Since August, 2012, we have had a self-supported 50-foot triangular
galvanized steel tower bracketed to a tool shed about 60 feet behind the house.
Atop, is an old (amplified) ChannelMaster VHF/UHF TV antenna aimed at Tulsa.
There are now 6 elevated radials cut for the 30 meter band fanning out from the 6-foot level. Connected between this counterpoise and a 6-wire quarter-wave skirt,
is the output of a link-coupled tuner fed with about 90 feet of open line
by the balanced (link coupled) tuner in the shack. I guess you'd call it
a half-wave shunt-fed vertical ground plane. WWV (my 'beacon')
and other stateside stations are stronger the wire vertical .
But on WWVH and DX, the half-wave vertical is the better of the 2.
73 es dx,
. . .Jim
P.S. Details on my old 75 m extended double Zepp,
rigs past and present, and more:
http://www.hamqth.com/w9jef