Ceramic bandpass filters target TETRA applications

28th September 2014

Mick Elliott

0 0

The AT22D range of Ceramic Bandpass Filters from Aaren Technology has joined the RF and microwave components portfolio at Aspen Electronics. The filter represents a low frequency design for ceramic technology with the 5 section Bandpass design having a centre frequency of 390MHz and features 6mm resonators.

The pass band is 30MHz with a rejection of 40dB at 300MHz and 480MHz and the insertion loss is 2.5dB max. Parts are available in surface mount or connectorised formats

Ceramic filters are made from high-dielectric constant ceramic resonators plus a capacitive coupling network to realise an “n” section cavity filter. The AT22D features 5 resonators, however the number of resonators can vary from 2 to 8 or more - dependent upon the required filter response.

Applications for this particular design could be related to any TETRA radio system requirement. However, given the wide frequency range over which these filters can be designed, applications can include, Cellular, PMR, Avionics or Defence, to name a few.

Ceramic filters are less expensive and smaller than either LC or cavity type filters. Typically available with a bandpass response, they are also available in “Notch” or band reject configurations. In addition ceramic designs can be configured as duplexers for transmit/receive applications.

Monoblock ceramic filters, formed from a single block of ceramic material are also available. This design of ceramic filter does not have a printed circuit board to secure their elements together, the entire block being surface mounted directly onto the circuit board.