Exact principal mode field for a lossy coaxial line

Exact field equations for a lossy coaxial transmission line with an infinite outer conductor are presented. The corresponding determinantal equation is solved to obtain an exact propagation constant from which errors in the usual microwave approximation and an alternative full frequency range approximation are calculated. The calculations show that the microwave approximation, although containing a large relative error at the lower frequencies, is still useful in practical applications     

First-order symmetric modes for a slightly lossy coaxialtransmission line

A complete set of solutions for Maxwell's equations to first order in the normalized surface impedance z_s of the coaxial conductors is found. The derivation of the fields outlined assumes a vacuum dielectric and an infinitely thick outer conductor. It starts from J.P. Stratton's work (1941) with a derivation of the determinantal equation for finding the eigenvalues for both the principal and waveguide modes in a lossy line. The first-order determinantal equation is found, preceded by an equation for calculating the proportionality constant for the fields intermediate between the center and outer conductor. The equations for lossy waveguide modes are new, and the principal mode fields include a term missing from the expressions that are found elsewhere in the literature. The resulting characteristic admittance and distributed line parameters are calculated; the distributed line resistance is significantly different from other calculations found in the literature     

Measuring adapter efficiency using a sliding short circuit

A simple technique for measuring the efficiency of adapters with losses less than 2 dB is described. The technique is useful in microwave applications where a moderate error in the measured loss is acceptable. This error is less than 10% of the loss for losses between 0.5 and 2 dB and is less than 0.05 dB below 0.5 dB. An expression for the error is given