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Microstrip Branch-Line Coupler (Aggregate): MBLCOUP

Symbol

Summary

MBLCOUP models microstrip branch-line coupler (90o hybrid). Model is a general one, i.e. it allows arbitrary lengths and widths of feeding lines as well as of series and shunt arms.

Topology

Parameters

Name Description Unit Type Default
ID Name Text TL1
W1 Width of feeding line at ports 1 and 2 Length W[1]
W2 Width of feeding line at port 3 and 4 Length W[1]
W3 Width of the line connecting ports 1 and 2 Length W[1]
W4 Width of the line connecting ports 1,3 and 2,4 Length W[1]
W5 Width of the Iine connecting ports 3 and 4 Length W[1]
L1 Length of the line connecting ports 1,3 and 2,4 Length L[1]
L2 Length of the Line connecting ports 1 and 2 Length L[1]
L3 Length of the line connecting ports 3 and 4 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.

Parameter Details

L1. Series arm connecting ports 1,3 and series arm connecting ports 2,4 have the same length L1.

L2. Full length of shunt arm connecting ports 1 and 2.

L3. Full length of shunt arm connecting ports 3 and 4.

Parameter Restrictions and Recommendations

  1. MBLCOUP uses MLIN and MSTEP (microstrip line and microstrip step of width) models, so all limitations of these models are applicable to MBLCOUP.

  2. For equal split 3 dB coupler (equal power split and 90 0 phase shift between ports 3 and 4):

    W1=W2=W3=W5;

    L1=L2=L3eff/4; (quarter of effective wavelength)

    W4 provides characteristic impedance of series branches equal to 1/√2 times characteristic impedance of feeding lines.

  3. Branch-line coupler with L2=L3 and L2≠L3 may provide more feasible design (see Reference [2]).

Implementation Details

MBLCOUP implies that coupler is mirror symmetrical relative to horizontal axis (see Topology).

Recommendations for Use

Feeding lines at ports may have different characteristic impedances. This is provided by proper choice of width parameters W1, W2 (see Topology).

To ensure specified power split, matching, isolation and phase shift between branched lines parameters may be derived in accordance with the recommendations in References [1], [2]. However, user may set parameters to values of his choice or use them for circuit optimization.

Layout

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.

References

[1] Mongia, R., Bahl,I.J. and Bhartia P., RF and microwave coupled-line couplers, Artech House Inc., Norwood, MA, 1999, pp. 243-247

[2] Toker, C., Saglam, M., Ozme, M. and Gunalp, N.,"Branch-Line Couplers Using Unequal Line Lengths," IEEE Trans. Microwave Theory Tech., vol. MTT-49, April 2001, pp. 718-721

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