RF Filter in Radio Broadcasting


In radio communication, the RF filter is a very important electronic equipment. In radio signals transmission, there will always be bands we don't need, such as some unnecessary spurious signals; or maybe for some special reasons, we don't need a certain range of frequency in the radio signals. At this time, we need to filter out unwanted frequency bands through RF filters. So what kind of electronic equipment is the RF filter and why is it so important? This share is to answer this question.


What is RF Filter

RF filter is an electronic filter, which is used to remove or retain a certain range of frequency bands in radio signals. It is generally used to process signals in the range of MHz to KHz (MF to EHF). It is applied to radio broadcasting equipment, wireless communication equipment, television equipment, including various transmitters and receivers. It is used to ensure that a certain range of unnecessary spurious signals won't be transmitted in broadcasting, and the section of the required signals will be retained.


In radio broadcasting, RF filter is a very important electronic component, because in the radio signals, in addition to the part we need, there are other ones we don't need. Therefore, we need RF filters to remove the unwanted parts. If you need to use an RF filter to work in the FM range, confirm the pass frequency range or suppression frequency range marked on the RF filter is in the range of 88 - 108MHz.


Functions of Different RF Filters


Generally speaking, different filters have four functions in radio broadcasting


Low Pass Filter


The Low pass filter is a filter that only allows the lower frequency to pass through. It will cut off the frequency band higher than a certain frequency. This part of the frequency band will be suppressed and not allowed to pass through.


It is often used to filter the noise from external circuits in audio signals. The sound signals processed by the low pass filter have a clear quality.


High Pass Filter


On the contrary, the high pass filter only allows higher frequencies to pass through and cut off the frequency band below a certain frequency. The audio signal in this band will be suppressed.


It is usually used to remove the bass from small speakers, so a high pass filter is often built into the speaker.


Band Pass Filter

The bandpass filter is a filter that allows a certain range of frequency signals to pass through and suppresses the other signals that do not belong to this frequency band. The frequency range that can be passed can be freely selected and can be two discontinuous ranges of frequencies.


It is often used in wireless receivers and transmitters. Its main function in the transmitter is to reduce the unnecessary part of the output signals so that the necessary data can be transmitted at the required speed and form in the limited bandwidth. In the receiver, its main function is to allow the desired amount of frequencies and cut off signals of other frequencies. Through the processing of the bandpass filter, the signal quality can be improved to the greatest extent and the competition and interference between signals can be reduced.


Band Stop Filter

The function of the bandstop filter is opposite to that of a bandpass filter. It is a filter that only suppresses a certain range of frequencies. Its function is similar to that of the bandpass filter, but they work in different ways.


Generally speaking, no matter what kind of filter it is, it is an electronic device that allows the signal to pass through with the help of a passband. In short, it is an electronic device that rejects the passage of signals of a certain range of frequencies and allows the passage of signals of other frequencies.


Why is RF Filter Important?


We know the function of the RF filter is to allow a certain range of frequencies to pass and prevent other frequencies from passing. But what is the meaning of this?


  • Improve the quality of the signals - In radio broadcasting, after using a proper RF filter, the signal interference generated by the communication system can be easily shielded, so that the quality of the required signal frequency can be maintained.


  • Avoid frequency interference - For example, mobile communication needs a certain amount of frequency bands to operate normally. If there is no suitable RF filter, the signals of various frequency bands will not be able to provide services at the same time, including Global Navigation Satellite System, public safety, Wi-Fi, etc.


In short, it can increase the proportion of the signals of required frequencies in the radio signal by suppressing the signal of some frequencies, so as to improve the fidelity of the radio signals.



Are you running your own radio station? And do you need to buy some proper filters for your radio broadcast equipment? The RF filters from FMUSER are your best choices! As a professional radio equipment provider, we provide complete types of high-quality RF filters and will provide you with affordable solutions based on your situation. If you have any needs in radio broadcasting, please feel free to contact us.








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