We offer RF filters for aircraft, aerospace, medical, power plant control, traffic signal, transportation equipment and a wide range of other applications.Radio frequency (RF) and microwave filters represent a class of electronic filter, designed to operate on signals in the megahertz to gigahertz frequency ranges (medium frequency to extremely high frequency). This frequency range is used by most broadcast radio, television, and wireless communication equipment (mobile phones, Wi-Fi, etc.).Accordingly, most RF and microwave devices will include some kind of filtering on the signals transmitted or received. Such filters are commonly used as building blocks for duplexers and diplexers to combine or separate multiple frequency bands.
What does an RF filter do?
Filters fulfil one of the following functions:- RF band-pass filter: selects only a desired band of frequencies
- RF band-stop filter: eliminates an undesired band of frequencies
- RF low-pass filter: allows only frequencies below a cutoff frequency to pass
- RF high-pass filter: allows only frequencies above a cutoff frequency to pass
RF Filter types
There are many different types or models for RF filters. Below are some of the more commonly used forms.Constant-k: The constant-k filter’s advantage lies in the ease of calculating values for the various components. This enables it to be simply designed with minimal theoretical knowledge about the mathematics, unlike many other filters. However, its performance does not quite match that of other filter types, although for many applications it is more than adequate.Butterworth: This type of filter provides the maximum in band flatness, although it provides a lower stop-band attenuation than a Chebyshev filter. However, it is also able to provide better group delay performance, and hence lower overshoot.Bessel: This filter provides the optimum in-band phase response and therefore also provides the best step response. It is often used where signals incorporate square waves, etc as the shape is maintained best of all.Chebyshev: This filter provides fast roll off after the cut off frequency is reached. However, this is at the expense of in-band ripple. The more in-band ripple that can be tolerated, the faster the roll off.Elliptic: This filter, also known as the Cauer filter, has significant levels of in-band and out of band ripple, and as expected the higher the degree of ripple that can be tolerated, the steeper it reaches its ultimate roll off.Show More
