Transcript Beverage Antenna Theory - LOUISIANA CONTEST CLUB

Purposes of the Amateur Radio
Service
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(a) Recognition and enhancement of the value of the
amateur service to the public as a voluntary noncommercial
communication service, particularly with respect to
providing emergency communications.
(b) Continuation and extension of the amateur's proven
ability to contribute to the advancement of the radio art.
(c) Encouragement and improvement of the amateur
service through rules which provide for advancing skills in
both the communications and technical phases of the art.
(d) Expansion of the existing reservoir within the
amateur radio service of trained operators,
technicians, and electronics experts.
(e) Continuation and extension of the amateur's unique
ability to enhance international goodwill.
Who is this W5WZ?
•Licensed in 1997 at age 26 (tnx W5LA)
•Competitive desire to operate instilled (tnx
KM5YL, W5LA)
•Contesting spark ignited at FD 1998 (tnx W5EW)
•Technical abilities challenged & stretched (thanks
K5RUS, K5ER)
The recent shack at W5WZ
My station has evolved just a bit…
KD5CAS station circa April 1998
(and only a single ladder-line fed dipole antenna & antenna tuner)
And just for fun…
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This is
KF5GDK,
ten years
before
earning his
license.
He was
calling
“DQ, DQ!”
Beverage Antenna for
Dummies
by W5WZ
(also a dummy)
Disclaimer: There are smarter
guys than me, read their stuff
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The ARRL Antenna
Book
• Lots of antenna info
• Chapter on LongWire and Traveling
Wave Antennas
Disclaimer: There are smarter
guys than me, read their stuff
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Low-Band DXing
by ON4UN
Complete chapter
on Beverage
receive antenna
Antenna Gain & Directivity
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Yagis are directive, i.e. there is less
gain in all but forward directions
Dipoles are also directive –
broadside in 2 directions
Inverted-Vees are also directive although omni-directional
The Challenge
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Multi-element Yagi transmit and receive
antenna are readily available for 10, 15,
20, & 40 meters
Tower height and structural requirements
for larger directional antennas (40 &
especially 80 & 160) gets complex and
expensive
We all want to work more stations on
every band, including 160, 80, & 40
Common Situation
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Ham station with wire antenna (usually dipoles)
on 160, 80, and sometimes 40
Constraints limit having 160m 3-element at 320
ft & 80m 4-element at 240 ft
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$$$
YL of the house
Neighbors, landlords, size of lot, etc.
Fear of extreme heights
You still want to work lots of stations on these
bands
Overcoming the Challenge within
the Constraints
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If you can’t increase transmit and receive
gain, then increase receive directivity
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Beverage antenna are ideal solution
• Cheap to build
• Simple to erect; one person can do it!
• Can be temporary: string the wire for a single
contest or the winter season
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The dB gained are in Signal-to-Noise ratio,
in a particular direction
Meet the Beverage
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A travelling wave antenna made of a
length of wire a small height above earth
• Terminated for unidirectional reception
• Un-terminated for bi-directional reception.
Practical Considerations
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Beverage antenna
• Have excellent directivity
• Gain usually never exceeds -3dBi
• Generally, longer Beverages have lower
elevation angles and narrower beam widths
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Resulting Benefit: Much higher Signal-toNoise ratio in the desired direction
In the Real World
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Imagine a W1 working Europe on a
vertical antenna with thunderstorms
in W4-land
Instead of S7 signal with S9+10dB
noise on the vertical, perhaps S5
signal with only S3 noise and
interference on the Beverage
What Do I Need to Build It?
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Length of wire
Supports and insulators
2 ground rods and clamps
Termination resistors (Ohmite
296-2368, 470 ohm, 2 watt,
flame-proof non-inductive,
$1.03 from Allied Electronics)
Feed-Point transformer (9:1)
• Store bought
• Homebrew
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Feed line to your receiver
Most of the Hardware
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F-connectors
& install tool
Transformers
Ground rod
clamps
Resistors
Antenna
switch
How Much Wire?
Computed for 2-meter high over good ground
160 meters
80 meters
40 meters
269
302
(0.5 l)
141
154
(0.5 l)
148
157
(1.0 l)
541
584
(1.0 l)
279
302
(1.0 l)
220
236
(1.5 l)
820
886
(1.5 l)
413
446
(1.5 l)
285
302
(2.0 l)
1089
1155
(2.0 l)
554
587
(2.0 l)
443
459
(3.0 l)
1345
1410
(2.5 l)
695
728
(2.5 l)
846
879
(3.0 l)
Supports & Ground Rods
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Remember to insulate the wire from
the support
• Trees
• T-posts
• Bamboo sticks, 4x4s, etc
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Standard copper-clad ground rods
and bronze clamps
Feed-Point Transformer
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Amidon FT-114-43
cost $2.25 each
AWG# 26 spool
cost $4.50
Needs a simple 8turn trifilar winding
for ON4UN design
Another Feed Point Transformer
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W8JI design – see W8JI.com
BN-73-202 cost $0.50 each
I find the design by W8JI much easier to
wind and implement
2-turn primary
5-turn secondary for 75
ohm feed line (6-turns for
50 ohm)
Test by placing 470 ohms
across secondary, sweep
SWR from 1.5 to 10 MHz –
should be flat around 1.2 –
1.4:1
Feed Point
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Feed line
connectors
Weather proof
enclosure
Connect to your Receiver
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Coax feed line
• 75 or 50 ohm
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Modify your transformer to accommodate
Protect your receiver while transmitting,
especially if QRO with both transmit and
receive antenna in close proximity
• “Front-end saver”, CQ magazine, Feb 1997,
pages 32-33.
Termination Point
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5-ft ground rod and clamp
Insulator
Wire-nut method to replace resistor without
soldering out in the woods
Feb 2010 - Initial Result at W5WZ
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Single-wire 285-ft beverage at 45 degrees,
average height about 4.5 feet
Just before local sunset, first evening on 80m
CW, transmitting 100 watts on dipole at 75-ft, I
worked
• Z31 - Macedonia
• LZ - Bulgaria
• YO – Romania
In the previous 12 years of hamming, outside of NA I had
only confirmed Canary Islands, Cyprus, Morocco, and
Suriname on 80 meters
Expanding the Beverage System
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Add length to the Europe beverage
Build additional antenna for specific
directions – ham population centers
Create/install switching scheme
Provide receive antenna signal to
both radios simultaneously
Benefit of Adding Length for 80
meters
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A picture is worth 1,000 words
Benefit of Adding Length for 160
meters
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Length REALLY matters on 160m!
Benefit of Additional Directions
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Ever try to rotate a 500 foot long
antenna?
• Pull up posts, move termination point,
reinstall posts and termination point.
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Use a standard multi-position
antenna switch to select different
beverage and thus heading.
Aerial Overview
•580
•480
•800
•480
ft
ft
ft
ft
beverage
beverage
beverage
beverage
at
at
at
at
45 degrees (Europe)
90 degrees (Africa)
270 degrees (VK/ZL)
315 degrees (Japan)
Provide Signal to Both Receivers
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The “Magic Tee”
http://michaelgellis.tripod.com/magict.html
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The advantage of the "magic tee" is that the
two output ports are isolated from each
other and the theoretical loss is only 3 dB.
How to Build the Magic Tee
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For 50 ohm coax, change the resistor to 25 ohms
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Be SURE to use the right mix of ferrite in the binocular
core.
• 73 mix is SUPERIOR
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Five bucks for 10 binocular toroids
• http://toroids.info/BN-73-202.php
• http://kitsandparts.com/
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Use a 7 turn primary, and a 10 turn center-tapped
secondary.
• The sigs will be 180 degrees out of phase
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OR, you can buy the $50 DX Engineering box...
Questions?