AbstractThe complex plasma admittance and the microwave emission has been observed in the range of plasma resonances at 1500 MHz (dipolar mode). The Tonks Dattner modes due to standing electron waves are included in our observations. Relations are derived between the coefficients for transmission, reflection and emission using network calculations connected with Nyquists formula. The noise temperature derived in this manner is only half the value of the electron temperature deduced from Langmuir probe measurements. This fact is confirmed by cavity measurements using the axial symmetric plasma mode.For the collision‐free discharge an explanation is proposed assuming a “semithermionic” emitting zone near the wall, the interaction with an external electromagnetic field mainly takes place in this thick region. According to the well known theory of Parker, Nickel and Gould a steeply decreasing electron profile near the wall also enforces a limitation of the longitudinal waves to such a wall near r