TELE-audiovision - The World’s Largest Digital TV Trade Magazine - page 172

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TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine
— 1 -12/2013
PRODUCT REPORT
High-Frequency Filters
The Benefits of HF Filters
If you’re an average end
user planning to set up
your own Ku band satel-
lite reception system you
simply get your antenna,
LNB, receiver and coax
cable to connect LNB and
receiver – no need to wor-
ry about anything else. If,
however, you’re the kind
of satellite enthusiast
who always wants to dig
a little deeper, or if you
run a professional cable
head-end or even a sat-
ellite uplink station, then
you might need some
more equipment, such
as high-frequency filters.
The market for those ac-
cessories is rather small,
and this is why only a
handful of manufacturers
can actually supply such
filters.
MFC (Microwave Filter
Co., Inc.) is one of them – a
company that specialises in
filters and optional equip-
ment for the high-frequency
range between 5 Hz and 50
GHz. MFC’s product port-
folio includes waveguides,
dielectric resonators, fre-
quency-separating filters,
standard filters, load resis-
tors (frequently called ‘dum-
my loads’), adapters and all
accessories that come with
those items.
Demand is particularly
high for C band filters, be-
cause this is where interfer-
ence frequently occurs and
– more importantly – the
right filter can work wonders
in eliminating such interfer-
ence.
High-frequency filters are
mostly used for eliminating
unwanted signals. More of-
ten than not, such interfer-
ing signals cannot only be
noticed on a single frequen-
cy, but also have a nega-
1. A sample spectrum: the signal level is high over a great
frequency range, no filter is used.
2. Using a high pass filter: only frequencies above the cut-
off frequency pass the filter, low frequencies are attenuated
substantially.
3. Using a low pass filter: only frequencies under the cut-off
frequency pass the filter, high frequencies are attenuated
substantially.
4. Band-Pass filter: combining both a high pass filter with a
lower cut-off frequency and a low pass filter with a higher cut-off
frequency. The result is that the centre band will pass the filter with
minimal attenuation.
5. Band-Rejection filter: in this case a low pass filter with a low
cut-off frequency is combined with a high pass filter with a high
cut-off frequency are combined. The result is that the centre band
is attenuated substantially.
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