Filtres fabriqués par 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 filter
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 signal
that is caused by the filter.
In general, phase shifts
become more pronounced
with higher frequencies,
which means digital signals
are more affected than
analog signals.
Problems
in the C Band
WiMAX and radar applications
(weather radar, in particular)
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 frequency
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 Microwave
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 causing
interference in the C
band.
The standard approach in
such a case calls for adding
a highly selective bandpass
filter, whose frequency
range corresponds to the
local footprint (that is 3700-
4200 MHz, 3400-4200 MHz,
etc.). More recently, however,
WiMAX was also launched
in many regions worldwide
in the 3400-3800 MHz frequency
band. The resulting
in-band interference in the C
band can no longer be eliminated
with the help of conventional
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 signal
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 example.
Filters for such high-frequency
applications are extremely
complex and a lot
of expertise and experience
are necessary for designing
state-of-the-art filters.
What’s more, special manufacturing
processes must be
adhered to, since we’re not
only talking about the odd
electronic switch or circuit
C-Band TX(MHz) RX (MHz)
Standard 5850–6425 3625–4200
Extended 6425–6725 3400–3625
New High-Frequency Filters by MFC
for the C-Band
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 interference
• 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
Rejection
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
Flanges
CPR229G (Input), CPR229F (Output)
Length
5.49“ (13.9 cm)
Weight
1.125 lbs. (0.51 Kg)
Finish
Gloss White Lacquer
here. High-frequency signals
are transmitted even without
electronic conductors
in place, which is why such
filters mainly consist of hollow
conductors in the form of
waveguides.
When you look at one of
those filters as an absolute
layperson, it’s almost impossible
to tell where and how
the filter can be integrated
into the existing reception
system. The answer is surprisingly
straightforward:
right at the antenna between
the feed horn and the LNB/
LNA.
Filters of this kind are
mainly produced with computer-assisted
milling in
combination with special
CAM software which calculates
the exact milling movements.
As far as the C band
is concerned, MFC is the
leading manufacturer worldwide
of filters for eliminating
interference. No other company
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 recently
introduced filters,
which MFC has started to
produce not too long ago
to see what this company is
made of. And of course TELEaudiovision
readers can take
a first-row seat when some
of MFC’s major new developments
take centre stage
below.
For filters in the C band
there’s no way around MFC,
a company specialising in the
development and production
of those special purpose filters,
and which therefore is
in a position to offer products
with top-notch specifications.
176 TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine — 11-12/2013 — www.TELE-audiovision.com