example 6.1

c0=2.998e12                                                        % [m/w]

df=1e5;

f=[4e9:df:6e9];

f0=5e9;                                                                 % Hz

lambda0=c0/f0

k0=2*pi/lambda0

mu0=4*pi*1e-7;                                                  % vacuum/air magnetic permeability

b=4e-3                                                             % coaxial outer radius [m]

a=1e-3                                                             % coaxial inner conductor radius [m]

etha0=377;

sigma_Cu=5.813e7;                                     % Cu conductivity [S/m] at 5GHz.

Rs=(2*pi*f0*mu0/(2*sigma_Cu)).^.5      % metal surface resistivity at 5GHz

% attenuation due to conductor [Np/m], coaxial air-filled

alpha_c_air=Rs/(2*etha0*log(b/a))*(1/a+1/b)          

er=2.8                                                            % Teflon relative electric permittivity

tand=.0004                                                    % tand is tan(d), d: skin depth

% attenuation due to conductor [Np/m], Teflon air-filled

alpha_c_teflon=Rs*er^.5/(2*etha0*log(b/a))*(1/a+1/b)        

alpha_d=k0*er^.5/2*tand                          % [Np/m] dielectric attenuation

Q_coax_air=k0/(2*alpha_c_air)                   % unloaded Q=beta/(2*alpha)

Q_coax_teflon=k0*er^.5/(2*(alpha_c_teflon+alpha_d))