As our life has been dominated by technology, the likelihood of electronic interferences has also increased to a greater extent. Every electronic item from lamp dimmer to garage door opener or other technical instrument contribute significantly to electrical noise experienced around us. Devices have also been developed to listen to that growing noise and react accordingly to the electronic neighbours also including Amateur Radio Transmitter.
In fact, nearly every active Amateur Radio experiences problem with noise or interferences which could involve interference to a neighbour's equipment or interference from a noisy devices which are commonly found in homes. However, the most important thing is that in most of the cases, these interferences can be cured successfully. The use of RFI filter or radio frequency interference filter is the usually recommended to solve the problem.
EMI or electromagnetic interference, or RFI or radio frequency interference is a type of electronic or electric emission that acts to impair, prevent or degrade the electrical circuit performance. There are various causes and reasons behind the emission of these interferences which originate from both man made and natural sources. These emissions are at times wanted in different sectors or often unwanted and dangerous for the electrical performance. Both, EMI and RFI, can be either conducted, means sent along power or signal lines, or even radiated, means they can propagate through free space causing noise.
RFI filters are passive electronic devices which suppress the conducted RFI or EMI emissions on any power or signal line. However, problem may be faced while controlling the emissions when it is radiated instead of conducted. The filter can be attached to specific device in question to limit or inhibit their EMI or RFI production. The use of RFI filter also inhibit the susceptibility of such devices to RFI or EMI emission from other devices in vicinity.
These filters are also named as per their usage and functionality. For instance, the filter which is used between any device and AC line is called AC power line filter. These filters are available in different configuration depending on the lines and device being protected. Therefore, it is very important to understand the characteristics of both the device in question and the filter which is to be used.
There are filters which allow passage of only certain types of frequencies through them. Therefore, if you use the RFI filter then it will allow a set range of EMI or RFI emissions to be transmitted to the device that has to be protected.
