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(Obsolete) Microstrip Rat-Race Coupler (Aggregate): MRRCOUP

Symbol

Summary

This element is OBSOLETE and is replaced by the Microstrip Rat-Race Coupler (Aggregate) (MRRCOUP2) element. MRRCOUP models microstrip rat-race coupler (180o hybrid). Model is a general one, i.e. it allows arbitrary lengths and widths of feeding lines as well as of all sections of the ring lines.

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 ports 2,4 Length L[1]
L2 Length of the line connecting ports 1 and 2 (about 3/4 w/len) 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. Line connecting ports 1,3 and line connecting ports 2,4 have the same length L1.

L2. Full length of line connecting ports 1 and 2.

L3. Full length of line connecting ports 3 and 4.

Parameter Restrictions and Recommendations

  1. MRRCOUP uses MCURVE and MTEE (microstrip arc line and microstrip T- junction) models, so all limitations of these models are applicable to MRRCOUP.

  2. For equal split 3 dB coupler (equal power split and 180 0 phase shift between ports 3 and 4):

    W1=W2;

    W3=W4=W5

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

    L2=3λeff/4

    W3,W4, and W5 provide characteristic impedance of corresponding lines equal to √2 times characteristic impedance of feeding lines.

Implementation Details

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

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.

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]. However, user may set parameters to values of his choice or use them for circuit optimization.

References

[1] Mongia, R., Bahl,I.J., and Bhartia P., RF and microwave coupled-line couplers, Artech House, Norwood, MA, 1999, pp. 260-264

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