Transmission Line Formulas

Concentric Transmission Lines
Characteristic impedance in ohms is given by

R-f resistance in ohms per foot of copper line, is given by

Attenuation in decibels per foot of line, is given by
Where: Z
ra
d1

d2

f


=
==
=

=

=

characteristic impedance in ohms,
radio frequency resistance in ohms per foot of copper line,
attenuation in decibels per foot of line,
the inside diameter of the outer conductor, expressed in inches,
the outside diameter of the inner conductor, expressed in inches,
frequency in megacycles.
Two-Wire Open Air Transmission Lines
Characteristic impedance in ohms is given by

Inductance in micro henrys per foot of line is given by

Capacitance in micromicrofarads per foot of line is given by
Attenuation in decibels per foot of wire is given by

R-f resistance in Ohms per loop-foot of wire, is given by

Where: Z
D
d
L
C
db
Rf
f


=
=
=
=
=
=
=
=
characteristic impedance in ohms,
spacing between wire centers in inches,
the diameter of the conductors in inches,
inductance in microhenrys per foot of line,
capacitance in micromicrofarads per foot of line,
attenuation in decibels per foot of wire,
r-f resistance in ohms per loop-foot of wire,
frequency in megacycles.
Vertical Antenna
   The capacitance of a vertical antenna, shorter than one-quarter
wave length at its operating frequency, is given by
Where: Ca
l
d
f
e
=
=
=
=
=
capacitance og the antenna in micromicrofarads,
height of antenna in feet,
diameter of antenna conductor in inches,
frequency in megacycles.
2.718 (the base of the natural system of logarithms).