RF Cavity Filters
FM band filters cover the entire FM band (from 87.5MHz to 108MHz). The fully adjustable input and output coupling provide superior tuning and performance all over the entire FM band. Available input powers range up to 20 kW. IN/OUT Impedance: 50OHM. Return Loss >26dB
Radio frequency cavity filters (RF cavity filters) are resonators inside a conducting box having coupling loops at the input and output. They are behind a duplexer and allows only certain frequencies to pass. RF cavity filters are one of the products provided by the TEM company. This company founded in 1977 comprising of a team of specialist in radio communication. It fully ventured into digital and FM transmitters of up to 40KW besides TV and microwave links in 1979 and 1981 respectfully.
The RF cavity filters are grouped in series according to their model to enhance effectiveness by making the pass band deeper depending on the surrounding frequencies. Their grouping relies on the input and output power on the filters. Some of the characteristics of the RF cavity filters include; Dimension, Temperature Range, Weight, Frequency Range, Maximum Input Power, Insertion loss, Return loss and Input Impedance.
RF cavity filters have two primary functions and these include: passing the desired frequency and rejecting as more of the undesired frequencies as possible. In such cases, they are of much important since they create a "notch" at the repeater. The RF cavity filters can also be made by combining a low-pass filter with a high-pass filter. They can also be referred to as band pass filter since they have completely flat pass band and when in the application, they attenuate all frequencies outside the passband.
The RF cavity filters also operate on the basis of "roll-off". It means that not all the frequencies outside the desired range are attenuated but just within a specified region outside the intended passband are attenuated but not rejected. This process is expressed in dB of attenuation per octave or decade of frequency. The design of these filters aims to make the roll-off as narrow as possible making the filter perform its work that is achieved at the expense of pass band or stop band "ripple."
Through the incorporation of the RF filters, have made it to control a significant share of the broadcasting industry with its profile renown across the globe.