Integrated Microwave Corp. offers the 928103, a 914.5 MHz ISM bandpass filter. This filter is designed to reject interference to and from adjacent radio services, like the cellular radio band.
This high-Q ceramic filter is designed using eight resonators that exhibit high Q (over 1000). The result is a compact filter that handles over 10 W CW, and has low insertion loss (5 dB max) considering its bandwidth. Elliptic function steepens the high-side and low-side rejection adjacent to the passband. Inductive coupling allows high-power operation and accommodates peak powers of over 200 W.
Large 12 mm Integrated Microwave ceramic resonators enable the construction of filters that approximate the performance and loss of cavity filters, but are far smaller. The filter measures 3.82 × 0.5 × 0.95 inches. The filter is designed for thru-hole mount that allows a relatively large filter to be soldered onto a host board without jeopardizing the reflow schedule used for smaller SMT components.
The filter-on-board approach reduces cost and improves performance by getting rid of cables and connectors. When a system needs continuous out-of-band protection, many other filter technologies cannot compete with passive ceramic filtering. Ceramic filters protect from the passband all the way down to DC, and from the passband up to 3× the center frequency. Ceramic filters can also offer static protection by shunting DC to ground and are frequently the best option for connecting an LNA to an antenna.
Other ceramic filter models are available from 280 MHz to over 10 GHz.