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Symmetric Tapped Multiple Coupled Lines on General Multilayer Substrate (Dynamic Model) (EM Quasi-Static): GMCLINST



GMCLINST is intended for use in tapped interdigital filters. GMCLINST models two cascaded sections of several (2 to 50) edge and/or offset broadside coupled microstrip lines with two tap ports attached between sections (see GMCLIN for a detailed summary).

This model is based on the GMCLIN model; it uses the same substrate GMSUB and has the same parameters (except section lengths).

GMCLINAT has an advantage over cascading two GMCLIN models because it runs twice as fast.

Equivalent Circuit


Name Description Unit Type Default
ID Element ID Text TL1
N Number of conductors   2
L1 Conductor length of 1st section Length L[1]
L2 Conductor length of 2nd section Length L[1]
Acc Accuracy parameter   1
GMSUB Substrate Definition Text GMSUB1[2]
*SaveToFile Switch "Save to txt file"=Yes/No   "No"
*FileName Name of text file with computed model parameters String Same as model name
Wi, i=2..nn- number of lines Width of conductor #n Length W[1]
Offsi, i=2..nn- number of lines Offset of conductor #n Length W[1]
CLi, i=2..nn- number of lines Number of layer containing conductor #n   1

[1] User-modifiable default. Modify by editing under $DEFAULT_VALUES in the default.lpf file in the root installation directory. See the AWR Microwave Office Layout Guide for details

[2] Modify only if schematic contains multiple substrates. See “Using Elements With Model Blocks” for details.

* indicates a secondary parameter

Parameter Details

See GMCLIN for a detailed description of GMCLINST parameters. GMCLINST differs from GMCLIN only in its length parameters.

L1. Length of front section between the input ports (Ports 1..3 in "Equivalent Circuit") and tap port.

L2. Length of tail section between the second tap port and output ports (Ports 4..6 in "Equivalent Circuit").

Parameter Restrictions and Recommendations

  1. The total number of layers cannot exceed 30.

  2. The number of conductors N cannot exceed 50.

  3. For more information about restrictions and recommendations common for GMCLIN, GMnCLIN, and GMCLINST, see GMnCLIN .

Implementation Details

Model implementation is based on the EM Quasi-Static technique described in [1]. It accounts for losses in metal and in substrate dielectric. Dispersion is partly included.


This element does not have an assigned layout cell. You can assign artwork cells to any element. See “Assigning Artwork Cells to Layout of Schematic Elements” for details.

Recommendations for Use

See this section in GMnCLIN for details. The section also includes examples of usage.

NOTE: The implementation of EM Quasi-Static models relies heavily on the involved numerical algorithms. This may lead to a noticeable increase in simulation time for schematics that employ many such models.

If a layer thickness is too small compared to the thickness of another layer, simulation time may also noticeably increase.


[1] M.B. Bazdar, A.R. Djordjevic, R.F. Harrington, and T.K. Sarkar, "Evaluation of quasi-static matrix parameters for multiconductor transmission lines using Galerkin's method," IEEE Trans. Microwave Theory Tech., vol. MTT-42, July 1994, pp. 1223-1228.

[2]R. Mongia, I. Bahl, and P. Bhartia, RF and Microwave Coupled-Line Circuits, Artech House, Norwood, MA, 1999.

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