tline_var :
A single-conductor, two-port transmission line with variable delay.

The tline_var primitive models a single-conductor, two-port transmission line with a characteristic impedance of Z0 and variable propagation delay. The variable delay is controlled by the xreal-typed input delay.

The real-array parameters ports and data together can define the frequency-dependent transfer characteristics between any selected source and destination ports of the transmission line. For instance, if the transmission or reflection coefficient from port 1 to port 2 can be described as the following s-domain transfer function H(s) having total of N partial fraction terms:

               b1_real + j*b1_imag                 bN_real + j*bN_imag
    H(s) = ---------------------------- + ... + ---------------------------- ,
           (s + a1_real + j*a1_imag)^m1         (s + aN_real + j*aN_imag)^mN

the parameter ports shall contain the following entries for the source and destination port indices:

    ports = '{ ..., 1, 2, ... }

and at the corresponding position, the parameter data shall have the 5*N+1 entries:

    data = '{ ...,
             N,                                             // number of terms
             a1_real, a1_imag, b1_real, b1_imag, m1,        // partial fraction term #1
             a2_real, a2_imag, b2_real, b2_imag, m2,        // partial fraction term #2
             ...
             aN_real, aN_imag, bN_real, bN_imag, mN,        // partial fraction term #N
             ...
           }

The parameters ports and data can be alternatively defined by a parameter definition file named filename which defines the same named parameters in Python format. For any transmission characteristics not specified, the primitive assumes the reciprocal characteristics from the ones defined (e.g. S21=S12) and ideal characteristics for the rest (i.e. no transmission loss).

This primitive is a pseudo-module describing a structural netlist of electrical circuits and not a behavioral model by itself. The XMODEL simulator extracts an event-driven behavioral model at run-time based on the circuit network described by these circuit-level pseudo-modules.

Input/Output Terminals

Name	I/O	Type	Description
pos_1	input	xreal	positive terminal of port #1
neg_1	input	xreal	negative terminal of port #1
pos_2	input	xreal	positive terminal of port #2
neg_2	input	xreal	negative terminal of port #2
delay	input	xreal	line propagation delay

Parameters

Name	Type	Default	Unit	Description
Z0	real	50.0	ohms	characteristic impedance
ports	real array	‘{0.0}	None	source/destination ports
data	real array	‘{0.0}	None	transfer characteristics data
filename	string	“”	None	parameter definition file
abstol	real	1e-3	None	absolute tolerance for event-filtering
reltol	real	1e-2	None	relative tolerance for event-filtering
m	real	1.0	None	multiplicity factor