TELE-audiovision - The World’s Largest Digital TV Trade Magazine - page 245

245
1 -12/2013
TELE-audiovision International —
全球发行量最大的数字电视杂志
T
he ability to receive 16 satellites
with a fixed antenna is quite the
sensation. After our exclusive
report of the Wavefrontier Toroidal
90 antenna in the 10-11/2001 edi-
tion of TELE-satellite magazine, this
true multifeed antenna became an
overnight success. Yet even the best
product isstill forsomepeoplenot the
perfect one. Naturally this includes
some hobbyists who, instead of doing
what everyone else does, rely more
heavily on their brain and of course
their set of tools in order to tell the
manufacturers that their products
could still be made better.
TELE-satellite reader Chris Mitiul
(
had a vision: reception of
20 satellites between 24.2° East and 30°
West with a fixed antenna. This of course
would not be a problem with a motorized
antenna but it would be for the neigh-
bors so some kind of noiseless solution
was necessary. The Toroidal 90 was not
designed for such a wide range.
But for Chris Mitiul expanding an azi-
muth range was nothing new to him. The
first successful attempts were made with
a Triax Multifocus antenna. The feed
Wavefrontier Toroidal-90
Wavefrontier Toroidal-90
Antenna
Tuning
mounting bar was simply extended to the
left and right. And if this works for a Triax
then it stands to reason that it should also
work for a Wavefrontier, even though the
reflector design is different.
So the first thing was to fashion two
multifeed holders that could each hold
two LNB’s. Such an aluminum holder was
made out of four feed mount halves, one
rail and seven screws. The rail is 15cm
long and the LNB holders each have a
width of 6cm. Normally the two LNB hold-
ers would be fastened to the rail with two
screws. Mounting to the Wavefrontier
antennaonly requiredone screw. Because
of this an LNB offset of about 25 cm was
achieved. This provided plenty of room
for any fine adjustments that may have
been needed. If the desired satellites at
the far eastern or western end prove to be
difficult, a multifeed holder for three LNB’s
could also be used.
Before the actual work – the search
for all the desired satellites – starts, the
Wavefrontier with its original LNB setup
should be aligned as best as possible. The
additional LNB holders are quite flexible
and can be turned in various directions.
The screws should only be slightly tight-
ened at first. This will help make it easier
to move the assembly while looking for
the desired satellites. To prevent possible
errors from occurring with the neces-
sary DiSEqC switches during the satellite
search, it is a good idea to initially connect
each LNB directly to the receiver or the
antenna measurement unit. Only when
all the satellites have been found and all
The end result
the screws are securely tightened, should
the DiSEqC switches be integrated with
the LNB’s.
You might soon be asking yourself why
the manufacturer doesn’t simply extend
the original LNB rail of the Wavefrontier
antenna. If the curve of the current rail
were extended left and right, a 100%
reflection of the signal would no longer be
guaranteed.
More than likely, because of TELE-satel-
lite reader Chris Mitiul, the engineers at
Wavefrontier will start working on some
kind of a solution. The “home made”
construction discussed above still has a
lot of room for improvement in terms of
fine-tuning adjustments.
We tried the idea here ourselves in
the TELE-satellite test department. The
assembly and hardware for the additional
LNB holders and rails we acquired second-
hand from a normal multifeed antenna.
The extra costs for the feed holder ended
up between €10 (2 LNB’s) and €15 (3
LNB’s) per piece. We managed an azimuth
range of 56°. This is 40% more than what
the Wavefrontier can do in its standard
configuration.
The vision to be able to receive 20
satellites did not come completely true.
And with the DiSEqC switches we never
managed to get more than 17 satellites
(see diagram). But these 17 satellites
could be selected from a significantly
larger azimuth range than was possible
before.
The bottom line: if the installation of a
motorized antenna is not possible, then
this would be the only viable alternative.
Assemblyof additional LNB’s
Extravagant cabling
This ishow it is all switched
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