get8TermModelUThru

      get8TermModelUThru   Constructs 8-term model based on measured SOLT and actual
                           SOL S-parmeters. Uses the Unknown Thru Method.
          [A,B,q] = get8TermModelUThru(G1,Gm1,G2,Gm2,Tm,freq_vec)
          input:
             G1,G2: [3,num_pts] actual (G) and measured (Gm) reflection coefficients
                    of standards used on port 1 and 2 respectively. Standards used in
                    G,Gm must be in same order (ie. G = [O,S,L] Gm = [Om,Sm,Lm])
             Tm: [2,2,num_pts] measured S-parameters of the unknown-thru
             freq_vec: [num_pts] frequency vector (in [Hz]) of the measurements
             phys_length: (optional) approximate physical length of the unknown
                          thru component in meters for velocity factor of 0.695.
                          Default is 0.05 (5cm)
          output:
             A,B: [2,2,num_pts] normalized error adapter [-delta_e e00
                                                            e11     1 ]
                  at ports 1 and 2 respectively
             q: [1,num_pts] thru error term e10e32