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Microstrip Line (Closed Form): MLIN




Name Description Unit Type Default
ID Element ID Text TL1
W Conductor width Length W[1]
L Conductor length Length L[1]
MSUB Substrate definition Text MSUB#[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.

Parameter Details

MSUB. This parameter specifies the microstrip substrate element, which defines additional cross sectional parameters of the transmission line. You can also add this substrate to the Global Definitions window and then reference the material from any schematic.

Implementation Details

This circuit component models a length of Microstrip Transmission Line. The model assumes a Quasi-TEM mode of propagation and incorporates the effects of dielectric and conductive losses. The parameters W (Strip Width) and L (Strip Length) are lengths entered in the default length units.

Circuit Model Synthesis

MLIN supports synthesis of physical parameters based on electrical specifications using the Transmission Line Calculator. To open the Transmission Line Calculator, right-click a transmission line element in a schematic and choose Synthesize.

To perform transmission line synthesis:

  1. In the Electrical property grid, select Target check boxes for desired electrical parameters and enter a corresponding value.

  2. In the Physical property grid, update frequency and substrate parameters if needed, then select Synthesize check boxes for transmission line physical parameters to synthesize based on the targets.

  3. Click the Synthesize left arrow to run the synthesis program. The values in both property grids update with the synthesized results. An analysis is also performed with the final physical values. If synthesis cannot achieve the target values, it shows how close it came.

  4. Click OK to update the selected transmission line element with the synthesized physical parameters. Expressions are overwritten with the new, evaluated values. You can click the Undo button on the program toolbar to revert all parameters in the schematic document to their pre-synthesized state. Parameters from substrate elements are never updated since typically substrate elements are used by more than one transmission line element. Click Cancel to close the dialog box without setting the parameters into the element.


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.


0.02 ≤ W/H ≤ 20 recommended

T/W ≤ 0.7 recommended

T/H ≤ 0.5 recommended

εr ≤ 16 recommended

1 ≤ εr required

Tand ≥ 0 required

0 ≤ Rho ≤ 1000 required

0 ≤ Rho ≤ 100 recommended


[1] E. Hammerstad and O. Jensen, IEEE MTT-S International Microwave Symposium Digest, p. 407, 1980.

[2] I. J. Bahl and D. K. Trivedi, "A Designer's Guide to Microstrip Line," Microwaves, p. 174, May, 1977.

[3] S. March, "Microstrip Packaging: Watch the Last Step," Microwaves, p. 83, Dec., 1981.

[4] R. Pucel, D. J. Masse, and C. P. Hartwing, IEEE Trans. Microwave Theory Tech., Vol. MTT-16, p. 342, 1968.

[5] G. Wells and P. Pramanick, Int. J. Microwave and mmWave Computer-Aided Design, Vol. 5, p. 287, 1995.

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