A71
VHF antennas for CW/SSB operation
2f. Bow horn antenna (Winkel Dipol)
for 2m SSB/CW mobile is an alternative to the low gain halo type,
it found some popularity for 2m FM mobile and stationary around
1970, and I had one such antenna in use for myself;
but later FM operation was changed to verticals, and the antenna
has been forgotten. For mobile I bought a Big Wheel,
but it turned out to have too much windload for the motorways,
although I am aware that some of my friends has used it, too.
The details shown are based on construction notice from LA8WF Jon
Dahl.
LA2NI made an array consisting of 4x fullwave dipoles and
believed he got 6dB gain - almost omni-directional,
feed impedance was 800/2=200W, so it
was easy to use a coax-balun down to 50W
I've got some notes from LA8WF, but it is not yet translated, VINKEL DIPOL (for some of his
Norwegian text) (German: Winkel-Dipol)
Balun and connections to coax cables using appliance electrical
box (LA1TN)
The halo-type VHF
antennas:
The ever popular HALO ("Squalo" according to
SM6ESG, but it is simpler - and it works!), purchased mine from
J-Beam in
Northamptom in 76 for £2.00, good value for money! Also tried
the German Big-Wheel, but it was too much windload on
Auto Bahn, so I got back to the Halo But have no idea if it is
good or bad. SM6ESG and other have copied the original version.
The squalo is made from 8mm alu-tubes, measures are shown in
between center of tubes (not ouside).
Since it is quite small, a 6m version would still
be suitable to have on the roof of the car, it is easy to scale
up.
Here is my calculated version of the "6m
SQUALO"
So the next might be to try an 80m version...
On a the VHF meeting in 2001 Morgan SM6ESG was selling two Halo
aerials he has built for LA8AV Egil. Gain -2....-2.5dBd,
not much, but quite useful for 2m mobile with 25W RF on SSB, so
it is obviously much interest for this sort of antenna.
Morgan mentions that he would like to try the alford slot (or
Babe Lincoln) antenna made from chicken mesh, but it may
attract some publicity when installed on his car.
See his mobile mount on /la8ak/91.htm
The Alford Slot aerial which is so popular for
microwaves in UK, seems to be based on the "Abe
Lincoln" mobile antenna,
see RSGB VHF-UHF Manual, 3rd edition (G6JP) pp7.28, the halo
aerial for 2m mobile is on 7.29
Alford slot antenna for 1296MHz beacon LA3UHG, unfortunately the
beacon is now QRT.
 |
 |
Morgan, SM6ESG and his HB9CV 2m antennas at the
Sca VHF meeting in June 2003.
Some secondary applications of "Coke" bottles for
weatherproofing coax connectors
Mobil?
2005.03.16