RF Waveguide Attentuators Information
RF waveguide attenuators are used to reduce the power level of a signal by a certain amount (gain), with little or no reflections. The output signal is reduced with respect to the input. Performance specifications for RF waveguide attenuators include operating frequency, EIA waveguide size, and VSWR. Operating frequency is the range of radio frequencies over which products meet all guaranteed specifications. The Electronic Industry Alliance (EIA) approves sizes for RF waveguide attenuation. Voltage standing wave ratio (VSWR), a unit-less ratio ranging from one to infinity, expresses the amount of reflected energy at the input or output of a device. A value of one indicates that all of the energy will pass through. Any other value indicates that a portion of the energy will be reflected.
General specifications for RF waveguide attenuators include waveguide material, waveguide cross-section, flange type, profile, and plating material. Common waveguide materials include aluminum, brass, bronze, copper, and silver. Typically, the waveguide cross-section is rectangular, elliptical or circular in shape. Union guide (UG) and connector pressurized rectangular (CPR) are the most common flange types. UG subcategories include choke and cover or plate. Choke flanges have an O-ring groove and choke cavity. Cover or plate flanges are square and flat. CPR flanges include types such as connector pressurized rectangular flat (CPRF), connector pressurized rectangular grooved (CPRG), and connector miniature rectangular (CMR). Most RF waveguide attenuators have a square, rectangular, or circle profile. Common plating materials include cadmium, nickel, rhodium, silver and tin. Non-plated products are also available.
RF waveguide attenuators that are sold in Europe must comply with the Restriction of Hazardous Substances (RoHS). RoHS requires all manufacturers of electronic and electrical equipment to demonstrate that their products contain only minimal levels of the following hazardous substances: lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyl and polybrominated diphenyl ether. RoHS became effective on July 1, 2006. By definition, lead-free RF attenuators contain less than 1000 ppm lead by weight. Some RF waveguide attenuators are suitable for programmable devices. Others are designed for military applications.