The RLB-E external reference (four ports) is a high performance Return Loss bridge optimized for ham radio applications. The external reference impedance is generally 50 to 300 ohms. The bridge components are precision SMD devices with a wide band 1:1 750 MHz SMD transformer using micro strip construction.
Return Loss Bridges operate by comparing the unknown impedance to a reference impedance. The INPUT port is connected to a test frequency source such as an RF oscillator or tracking generator from a spectrum analyzer. The DET (detector) is connected to an oscilloscope or spectrum analyzer for analysis. The DUT (device under test) is connected to the item to be tested such as an antenna, network, coax, or any other device. If the impedances are exactly equal, than the detector output will be essential zero.
However, Return Loss performance is very dependant on the characteristics of the reference. Most bridges have a residual return loss from 30-40 dB (1000-1 to about 10,000). This high sensitivity allows for measuring equivalent SWR of 1:101 or better.
Each RLB-E Return Loss Bridge comes completely assembled in a premium shielded die cast aluminum alloy A380 housing. Each housing is blue baked enamel per Federal Standard 595 #25109 over primer wash per DOD-P-15328