6 db
Mike Furrey WA5POK/4
April 17, 2014
Brandon Amateur Radio Society
1. What does the “V” stand for in VSWR?
2. Are we more concerned with VSWR at (circle one)
a) the antenna or b) the radio?
3. A length of coax will have greater losses at (circle one)
a) longer ʎ or b) shorter ʎ.
4. The impedance of a ½ ʎ dipole in free space is ____.
5. The purpose of an antenna tuner is (circle one) a) make
the antenna happy or b) make the radio happy.




VHF band
50.0 – 50.1 MHz CW only
50.1 – 54 MHz CW, RTTY, Image, Data, Phone
Available to all classes of radio operators
(except for the old Novice class)




Transmitter power output is legal limit
Sometimes called “The Magic Band”
QSOs tend to be short due to fast QSB
Most QSOs involve exchanging grid square
designation (EL87 for my Florida QTH)







Good for local communications/Nets and ragchewing
BARS 6 meter net – Tuesdays @ 7 PM on
50.2 MHz (WB4AKA holds court)
Working States
Working DX
Working Grid Squares for VUCC award
Grid Square Expeditions – FUN!
Contesting – Lots of categories for simple
stations/setups








F2 layer skip during high levels of sunspots
Sporadic E skip
Meteor Scatter
Moon Bounce - EME
Ducting
Check CW beacons for propagation
Many Hams constantly monitor 50.125 MHz
for activity and openings.
Additional on-line propagation tools listed in
reference section



FT-620B – Got me started
Other older famous 6 meter rigs:
Swan 250, Drake TR-6, Heathkit Lunch box
and SB110, Gonset Communicator G-50,
Ameco TX-62
Most HF rigs manufactured in the last 15
years include 6 meters








Dipole
Ground Plane
Delta Loop/Square Loop/Bi-square
End Fed Zepp
J pole/Slim Jim
Extended Double Zepp
Hentenna
Beams and Beam adaptations





Simple to build 1/2ʎ antenna
Formula: Lft = 468/fMHz
Install horizontally, inverted V, sloping, or
vertically
Feed through a choke balun with 50Ω or 75Ω
coax
Have a “Buddy Pole” center? Get two CB
whips, cut each to 1/4ʎ for 1/2ʎ 6 meter
dipole.





Simple to build 1/4ʎ vertical
Make from wire, copper tubing, or cut a CB whip
Formula: Lft = 234/fMHz
Gain is same as dipole but omni-directional and
lower angle of radiation
Feed with 50Ω coax – excellent match when
radials slope down 45°




In a pinch, a 2 meter 5/8ʎ mobile antenna can
be used on 6 meters (I have!)
1/4ʎ on 6 meters is 55.9”
5/8ʎ on 2 meters is 50” and impedance
matching is provided by a low inductance coil
The above combination provides a baseloaded vertical antenna that works on 6
meters.




A 1ʎ delta or square loop is easy to build and
tune (I worked all over NA with my FT-620B and 10 watts output!)
About 1.5 db gain over a dipole
Feed with ¼ʎ matching stub of 75Ω coax
Formulas:
Loop: Lft = 1005/fMHz
Stub: Lft = Vf(246/fMHz)
Vf = velocity factor of coax; use .66 for
polyethylene coax and use .82 for foam coax
SINGLE ELEMENT QUAD LOOP
6 METER DELTA LOOP IN ATIC
2ʎ loop open at the top
4.5 db gain over dipole
Multi-band coverage
with ladder line to
tuner
 Use ¼ʎ 450Ω ladder
line to connect to 50Ω
coax for single band
operation.







Easy to build end-fed (voltage fed) ½ʎ antenna
Same gain as a dipole
Advantages:
- No center support needed for feed line
- Hide the feed line in a tree.
- Hide the whole antenna in a tree!
Formulas:
antenna length:
Lft = 468/fMHz
transmission line length:
Lft = 234/fMHz
Take that end-fed Zepp and
stretch it out vertically!
 Looks like a “J”… (well, a backwards “J” in this

illustration) …
Make it out of wire and hide it
in a tree
 Check reference section for
websites that include a “J” pole
calculator for Cu tubing like
what was built as shown in the
next slide

Variation of the “J”
pole
 Same length but a 1ʎ
radiator is folded back
on itself.
 Claims of up to 3 db
gain over the “J” pole
 Link to this is in
References






Extended Double Zepp is Simple to build, center fed
antenna with 3db gain over a dipole
Formula: Lft = 1170/fMHz
Feed with open wire line and a tuner, this antenna
will function on 20-6 meters
May need 6 meter tuner (easy to build) since some
tuners, especially auto-tuners, may have a limited
matching range on this band.
Can be matched to coax for single band operation
without a tuner as shown on next slide






Hentenna means “Strange” antenna
Developed by the Japanese for 6 meters
Easy to build 1⅓ ʎ Rectangle loop that
provides 3-4 db gain over a dipole
Easily fed with 50Ω coax
Can be oriented vertically or horizontally
I have used this type of antenna on 20 and 10
meters effectively for many DX QSOs.



Quack Beam – So named because my good
friend, AD5Q modeled and provided the
dimensions for me to build this beam.
My criteria:
- Feed directly with 50Ω coax
- Elements are insulated from the boom
- No gamma, “T” matches, hairpin matches,
or baluns (well … a choke balun at feed point).
Link to my article in reference section
I used this quad in DL99.
Add a reflector .12ʎ (30”)
behind the driven loop for
an increased gain of 5 to 6
db (equivalent to a 3 element beam)
 Formulas:
Driven: Lft = 1005/fMHz
75Ω Stub: Lft = Vf(246/fMHz)
Reflector: Lft = 1030/fMHz


A 2 element beam with
the element ends
folded in 90° to provide
a more compact
antenna.
 Photo by KG4JJH
 Check reference
section for details


You can either home brew or purchase a kit
from DX Engineering ($139) to add up to 3
elements to your HF beam (bolts on the boom, no
mods to the HF beam!)



No additional feed lines are needed
Original article is in QST September 2011
pages 40-42
Links to article and DX Engineering in
reference section; preceding photo is from article








Small – 1/2ʎ dipole at 51 MHz is 9’2” long
Measure carefully!
2” change can shift resonant frequency 1 MHz!
Easy to hide in strict HOAs
Not much material thus a low cost antenna
Minimal tools required to build these antennas
SWR meter is only test equipment required
Wide bandwidth due to wavelength-toconductor ratio





Pick an antenna.
BLOW the dust off your soldering iron.
Build it and experiment with it.
Join the fun of “The Magic Band!”
At least lets keep WB4AKA busy!
73 de WA5POK/4
Making life easier for VHF operators!

50 MHz Beacon Map
http://www.k9mu.com/map/

G3USF's Worldwide List Of 50MHz Beacons
http://www.keele.ac.uk/depts/por/50.htm

6 Meters and the Power of the Reverse Beacon Network
http://reversebeacon.blogspot.com/2013/06/6-meters-and-power-ofreverse-beacon.html

Real Time QSO/SWL 50 MHz Map
http://www.dxmaps.com/spots/map.php

Grid Square map
http://www.qsl.net/w0jt/Contests/GridMap-US-MoreDetail.jpg

Six Meter International Radio Klub – Lots of 6 meter reasources
http://www.dxmaps.com/spots/map.php

Radiowave Propagation Center
http://prop.hfradio.org/

J pole Antenna Calculator
http://www.hamuniverse.com/jpole.html

Slim Jim Antenna Calculator
http://www.m0ukd.com/Calculators/Slim_Jim/

Hentenna by Dk7ZB
http://dk7zb.darc.de/Quadlong/Hentenna.htm

The Hentenna Re-visited
http://www.hamuniverse.com/hentenna.html

6 Meter Quack Beam
http://physicsfiles.com/6%20meter%20Quack%20beam.pdf

Moxon Antenna Project
http://www.moxonantennaproject.com/index.html

6 meter wire Moxon
http://www.nc4fb.org/wordpress/6-meter-moxon-wire-beam-antenna/

A 6 meter Moxon
http://www.kg4jjh.com/6mmoxon.html

DX Engineering 6 meter 3 element beam add-on kit
http://www.dxengineering.com/search/product-line/dx-engineeringw1zr-6-meter-add-on-kits/beam-antenna-add-on-kit-band/6-meters

QST Article
http://static.dxengineering.com/pdf/Hallas.pdf
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising