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Asymmetric Edge Coupled Microstrip Lines (Closed Form): MACLIN



Name Description Unit Type Default
ID Name Text TL1
W1 Conductor 1 width - nodes 1&&3 Length W[1]
W2 Conductor 2 width = nodes 2&&4 Length W[1]
S Gap width conductors 1&&2 Length 40 um
L Physical length Length L[1]
MSUB Substrate definition Text MSUB1[2]

[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.

Implementation Details

This circuit component models a section of two edge coupled asymmetrical microstrip lines.

The parameters W1, W2 (strip widths), S (gap between strips), and L (line length) are dimensions entered in the default length units. The parameter MSUB specifies the microstrip substrate element, which defines additional cross sectional parameters of the transmission line. If blank, a default is used.


This model has two implementations: basic implementation and modified implementation. Basic implementation provides frequency-dependent behavior that matches reference [1]; unfortunately, formulation [1] is not very good in low frequency and DC region. Modified implementation improves low frequency and DC behavior but demonstrates frequency behavior somehow different from those of basic implementation at frequencies below 10 GHz. For example, model may underestimate total loss if dielectric loss substantially exceeds conductor loss. MACLIN is not intended for modeling substrates with very large loss tangents (say, above 0.02): Loss of this magnitude should be modeled by EM Quasi-Static models.

How to switch between implementations

Right-click on schematic that contain MCLIN model(s), select Options from pull-down menu, than select Modeling Options tab, go to pull-down list "Model compatibility version".

To set all MCLIN models in this schematic to basic implementation select Version 5.53 from pull-down list.

To set all MCLIN models in this schematic to modified implementation select Version 6.0 or Version 6.5 from pull-down list.

Note that switch also affects MCLIN, MCFIL, SCLIN.


This element uses line types to determine its layout. By default, the layout uses the first line type defined in your Layout Process File (LPF). You can change the element to use any of the line types configured in your process:

  1. Select the item in the layout.

  2. Right-click and choose Shape Properties to display the Cell Options dialog box.

  3. Click the Layout tab and select a Line Type.

  4. Click OK to use the new line type in the layout.

See “Cell Options Dialog Box: Layout Tab ” for Cell Options dialog box Layout tab details.

See “The Layout Process File (LPF)” for more information on editing Layout Process Files (LPFs) and to learn about adding or editing line types.

Recommendations for Use

Modified implementation of MACLIN better works in time-domain than basic implementation; however, in critical time-domain designs EM Quasi-Static models like GM2CLIN are preferable.


[1] R.Mongia, I.Bahl, and P.Bhartia, RF and Microwave Coupled-Line Circuits. Boston: Artech House, 1999, ch.4.

[2] P.K. Ikalainen and G.L. Matthaei, "Wideband, Forward-Coupling Microstrip Hybrids With High Directivity," IEEE Trans. Microwave Theory Tech., vol. MTT-35, Aug. 1987, pp. 719-725

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