C Band Interference Elimination Filter
C Band Interference Elimination Filter: What are they?
C Band Interference Elimination Filter are used by satellite receivers to remove sources of interference which have frequencies in the C Band and are very close to their frequency of operation. Examples of interferers are the WIMAX signals and signals from C-Band RADAR.
If these spurious signals are not removed, they can cause problems like intermodulation or saturate the LNA. Since these signals can appear below and above the operating frequency of the satellite receivers, you will need a band pass filter.
AWG Tech supplies a number of C Band Interference Elimination Filter for the C-Band satellite receiver and extended C-Band satellite receiver. You can also request for a C Band Interference Elimination Filter with a customized bandwidth.
Specification of a typical C-Band Interference Elimination Filter
WIMAX operates in the frequency band from 3.4-3.8GHz. A portion of this frequency band is within the passband of many C-Band satellite receivers. Because of this, a “standard” filter would not be able to remove the interferer as part of the interference is in the passband of the filter.
Let’s suppose we have a WIMAX signal operating at 3.7GHz. This signal would cause problem to a receiver operating in the region of 3.7-4.2 GHz.
To get around this issue, AWG Tech added a pole to the C-Band filter that will provide a rejection of about 30 dB at 3.7 GHz and allow the remaining C-Band from 3.78 – 4.2 GHz to pass through.
Here are some specifications of ABPF-3900MBW420 -01
- 1 dB passband : 3.78 – 4.2 GHz
- Passband Insertion Loss : 0.6 dB at 3.9GHz
- Lower Frequency Rejection : 30 dB at 3.7 GHz
- Upper Frequency Rejection : 30 dB at 4.35 GHz
Loss @ fo
|ABPF-3800MBW800-01||3.8 GHz||3.4 – 4.2 GHz||0.8 dB max||20 dB @ 3.2 GHz|
20 dB @ 4.3 GHz
|ABPF-3900MBW600-01||3.9 GHz||3.6 – 4.2 GHz||0.8 dB max||20 dB @ 3.55 GHz|
20dB @ 4.25 GHz
|ABPF-3915MBW500-01||3.915 GHz||3.665 – 4.165 GHz||0.8 dB max||20 dB @ 3.615 GHz|
20 dB @ 4.215 GHz
|ABPF-3950MBW500-01||3.95 GHz||3.7 – 4.2 GHz||0.8 dB max||20 dB @ 3.65 GHz|
20 dB @ 4.3 GHz
|ABPF-3990MBW420-01||3.99 GHz||3.78 – 4.2 GHz||0.8 dB max||20 dB @ 3.725 GHz|
20 dB @ 4.325 GHz
|ABPF-4050MBW300-01||4.05 GHz||3.9 – 4.2 GHz||0.8 dB max||20 dB @ 3845 GHz|
20 dB @ 4.3 GHz
C Band Interference Filter for Satellite – Wondering if and why you need one?
The C Band is the name given to a range of frequencies that broadcast between 4 and 8 GHz. Historically the C band spectrum was utilized by long range satellite broadcasts, specifically TV and Radio Stations. Historically, the primary benefit of using C Band was that a larger range of stations could be received by a user with a C Band satellite dish.
However, over the last few years, there has been added traffic within this frequency range, most particularly caused by Radar and WiMAX installations. Studies show that C Band frequencies within up to a 12km radius from a Fixed WiMAX station could be impacted negatively. This potential disruption to the quality of a Satellite Television signal has necessitated the introduction of a specific type of Band Pass filter – the C Band Interference Filter for Satellite.
In order to determine if you need a C band interference filter for satellite, it is necessary to understand exactly what the components of a C-band interference filter.
What is An Interference Filter?
An interference filter for satellite is really just a band pass filter that allows predefined signals, in this case certain pre-defined C Band frequencies, to pass through, while blocking any other signals. The interference filter is set to only allow the pass through of a tight and specific range of C Band frequencies. The C Band frequencies most often used by WiMAX and radar, are explicitly attenuated.
While there are two different kinds of band-pass filters – Active band pass filters and Passive band pass filters. The C-band filter is usually a passive filter which does not need to be connected to an external power source and usually consists only of passive components like capacitors and inductors. Active filters, needing an external power source, are usually utilised in highly specific cases.
Band pass filters can be used in both wireless transmitters and receivers. In the specific case of a C Band Interference Filter for Satellite, the filter acts as a receiver and only allows a select range of frequencies to be decoded or heard. Any signals or unwanted frequencies are blocked. The filter also is able to optimize the sensitivity of the receiver.
It doesn’t matter if the filter is being used in a transmitter or receiver – the filter, being perfectly optimised for the frequency and purpose of the signal, will be able to maximise the amount of signals that can be transferred, and at the same time the band pass filter will reduce any interference or competition between alternate signals.
Interference Filter for Satellite
When selecting a C Band interference filter for Satellite, the main features a user should look for are:
- All terrestrial interference in C-Band (WiMAX, Radar and C-Band transmitters) should be completely blocked
- The unit should be easy to install between the feed and the LNB
- The filter must be compatible with the most common C-Band LNBs
- Since it is being installed outdoors, the Filter must be environmentally sealed and moisture resistant
- The filters center frequency should be as close as possible to the frequency of the C-Band broadcast.
Despite all the challenges that the various technologies are facing within the C-band spectrum, it is very clear that C-Band as a satellite transmission medium is here to stay. Plans are already in place to start broadcasting even more digital services through the C-band spectrum. If you are having interference on your C-band reception, it is definitely necessary to get the issues addresses as soon as possible.
With a deeper understanding of the utilization and reason for a C band interference filter for satellite, it is much easier to decide if this filter is something you need. It is important to determine the Center Frequency (what frequency you get your satellite transmission on) so that you can get as narrow a C band interference filter as possible. The tighter the center bandwidth, the cleaner your signal will always be. Also ensure that the problems you are facing with your signal are definitely cause by overlapping C-band frequencies. There are other issues which may be at fault, and you don’t want to incur the expense and trouble of installing a C band interference filter for satellite sand then discover that the issue is still prevalent.
If you are in doubt as to what frequency your satellite dish receives on, or the range of the C band filter you need, please contact us for assistance.