RF waveguide tees are components that allow one signal or line to branch into two or more lines. They are made of aluminum, brass, bronze, copper, or silver and have circular, elliptical, or rectangular cross sections. There are several basic types of products. E-plane tees or series tees are used to change the direction of electric field (E-field) lines. They provide a smooth change in direction, allowing the waveguide axis to remain parallel to the direction of the transverse E-field polarization. H-plane tees or shunt tees are RF waveguide tees that change the direction of magnetic field (H-field) lines. Like E-plane tees, H-plane tees provide a smooth change of direction, allowing the waveguide axis to remain parallel to the direction of the transverse polarization. Hybrid tees are RF waveguide tees that combine the features of E-plane tees and H-plane tees.
RF waveguide tees use flanges to connect waveguide sections or terminate waveguide components. Most flanges are square, circular, or rectangular in shape and plated with cadmium, nickel, rhodium, silver, or tin. Union guide (UG) is the military standard MIL-DTL-3922 for a range of flange types. Cover or plate flanges are flat, square UG-style flanges. Choke flanges are UG-style devices with an O-ring groove and choke cavity. They are often used to minimize the effects of flange discontinuity. Connector pressurized rectangular (CPR) flanges meet Electronic Industry Association (EIA) specifications and are used in many non-military applications. CPR variants include miniature (CMR), grooved (CPRG), and flat (CPRF) flanges. Mill-back flanges are made with the opening of the flange face equal in size to the inside of the waveguide, which is soldered into a larger milled opening at the rear of the flange.
Performance specifications for RF waveguide tees include operating frequency range, EIA waveguide size, length, and voltage standing wave ratio. Operating frequency range is the range for which RF waveguide tees meet all guaranteed specifications. EIA waveguide sizes have a prefix of WR and indicate the widest inside dimension of the waveguide in hundredths of an inch. For example, WR650 is 6.50 in. wide, WR90 is 0.90 in. wide, and WR75 is 0.75 in. wide. Length is also measured in inches. Voltage standing wave ratio (VSWR) is a unit-less ratio ranging from 1 to infinity that expresses the amount of reflected energy at the input or output of the device. A value of one indicates that all energy passes. Any other value indicates that a portion of the energy is reflected.