TELE-audiovision - The World’s Largest Digital TV Trade Magazine - page 176

Model 13961W-I
- International (Extended)
C-Band Interference Elimination Filter
• No other filter in the industry provides as much rejection of undesired signals in
such a compact size.
• Eliminates WiMAX, RADAR and virtually all other sources of out-of-band inter-
• Lightweight - Aluminium Construction
• Ready to install between LNB & feed horn
Pass band
3.6 - 4.2 GHz
Pass band Loss
0.5 dB Typ @ centre band
0.5 dB Typ roll-off @ band edges
Pass band VSWR
1.5:1 Typ
Group Delay Variation
8 ns Max
45 dB Typ @ 3.55 GHz / 4.25 GHz
55 dB Typ @ 3.45 GHz / 4.35 GHz
70 dB Typ @ 3.40 GHz / 4.40 GHz
CPR229G (Input), CPR229F (Output)
5.49“ (13.9 cm)
1.125 lbs. (0.51 Kg)
Gloss White Lacquer
TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine
— 1 -12/2013
for the C-Band
New High-Frequency Filters by MFC
filter or low-pass filter.
• Decibel
This measuring unit gives
the relation between two
signals (P1 and P2) based on
the following equation:
dB = 10 Log10 (P1/P2)
• Insertion loss
Like any other active or
passive element between the
antenna and the receiver/
transmitter the use of a fil-
ter causes a certain amount
of overall signal attenuation.
The insertion loss parameter
indicates that attenuation,
which should be as low as
possible (max. 3 dB).
• Phase shift
This parameter indicates
the runtime shift of the sig-
nal that is caused by the fil-
ter. In general, phase shifts
become more pronounced
with higher frequencies,
which means digital sig-
nals are more affected than
analog signals.
in the C Band
WiMAX and radar applica-
tions (weather radar, in par-
ticular) are major sources of
interference in the C band.
For uninterrupted C band
reception it can therefore
be recommended to use
band-pass filters that only
allow the required frequency
range to pass through.
As far as the C band is
concerned, we have to draw
a line between the standard
C band and the extended C
band. To complicate matters
even further, some regions,
such as Russia for example,
use a slightly different fre-
quency range for the C band.
This means that the actual
frequency band defines the
filter to be used. In recent
years, WiMAX (Worldwide
Interoperatibility for Micro-
wave Access) has become a
source of much frustration.
WiMAX is used for wireless
Internet access in the 2300
MHz, 2500 MHz and 3500
MHz bands and as such has
enormous potential for caus-
ing interference in the C
The standard approach in
such a case calls for add-
ing a highly selective band-
pass filter, whose frequency
range corresponds to the
local footprint (that is 3700-
4200 MHz, 3400-4200 MHz,
etc.). More recently, howev-
er, WiMAX was also launched
in many regions worldwide
in the 3400-3800 MHz fre-
quency band. The resulting
in-band interference in the C
band can no longer be elimi-
nated with the help of con-
ventional band-pass filters,
since signals from WiMAX
transmitters using 3700 MHz
and consequently impacting
the 3700-4200 MHz range,
will still come through with
a standard band-pass filter
that allows all frequencies
between 3700 and 4200 MHz
to pass through. This means
the interfering WiMAX sig-
nal is not blocked and such
a filter does not solve the
problem. A special filter is
required in such a scenario
– one that only lets through
signals on frequencies of
3750 MHz and above, for ex-
Filters for such high-fre-
quency applications are ex-
tremely complex and a lot
of expertise and experience
are necessary for design-
ing state-of-the-art filters.
What’s more, special manu-
facturing processes must be
adhered to, since we’re not
only talking about the odd
electronic switch or circuit
here. High-frequency signals
are transmitted even with-
out electronic conductors
in place, which is why such
filters mainly consist of hol-
low conductors in the form of
When you look at one of
those filters as an absolute
layperson, it’s almost impos-
sible to tell where and how
the filter can be integrated
into the existing reception
system. The answer is sur-
prisingly straightforward:
right at the antenna between
the feed horn and the LNB/
Filters of this kind are
mainly produced with com-
puter-assisted milling in
combination with special
CAM software which calcu-
lates the exact milling move-
ments. As far as the C band
is concerned, MFC is the
leading manufacturer world-
wide of filters for eliminating
interference. No other com-
pany even comes close to
MFC and its comprehensive
portfolio of filters for radar,
WiMAX or any other signal
causing interference.
All it takes is a look at re-
cently introduced filters,
which MFC has started to
produce not too long ago
to see what this company is
made of. And of course TELE-
audiovision readers can take
a first-row seat when some
of MFC’s major new devel-
opments take centre stage
For filters in the C band
there’s no way around MFC,
a company specialising in the
development and production
of those special purpose fil-
ters, and which therefore is
in a position to offer prod-
ucts with top-notch specifi-
RX (MHz)
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