Broadband WiMAX filters

Radio Frequency Systems has unveiled a family of dual ultra-lightweight RF filters designed for worldwide interoperability for microwave access (WiMAX) applications.

Founded on the company’s polymer-based air-cavity filters, the family has a body weight of 300 g — less than 50% that of other WiMAX filters.

The family comprises four separate filters with passbands designed to support the 2.2, 2.3, 2.5 and 3.5 GHz WiMAX sub-bands, claimed to be the widest range of sub-bands allocated for WiMAX across the Asia–Pacific, Americas and European regions.

Specifically designed for time-division domain, all members of the family have common package dimensions, regardless of passband frequency.

The polymer technology provides a filter with a body weight of less than half that of aluminium filters, yet retains optimal performance. Mechanical stability and high-precision mechanical tolerances are ensured by incorporating glass fibre and mineral filler reinforcement in the polymer material.

Optimum thermal expansion properties are achieved via a blend of polymer terminals.

Founded on high-Q cavities and engineered to provide premium RF performance, the filters have low insertion loss (typically 0.3 dB in-band at room temperature) and good power handling.

Each member of the family provides two filters within its silver-plated combline-construction body. The filters feature multiple resonators — two x six resonators within the 2.2 and 2.3 GHz variants; and two x eight resonators in the 2.5 and 3.5 GHz models — with all resonators in exactly the same position for interchangeability.