Function purpose of a biased T circuit

Wideband Bias Tee
Gary W. Johnson, WB9JPS 11-8-08

Bias tees are useful for injecting DC bias to a device under test while isolating an
instrument from any DC offset. For instance, you may be applying a bias to the base of a
transistor while using a network analyzer to measure S parameters. Or, when testing a
modulated laser diode, a DC operating current is required while an ac modulation rides
on top of that.

So is this saying if I have a LNA i am testing that I need to DC bias my RF signal input signal to obtain accurate measurement on the RF output? Just trying to gather myself on the purpose of using a biased T circuit

A bias T allows you provide DC power to device without interfering with the RF signal. Often amplifiers will have one pin for both DC in and RF out. The bias T allows DC power to flow into the amp from the power supply, but blocks the RF from traveling back into the power supply.