Miniaturized Branch Line Coupler With Open Stubs

7/31/2019 Miniaturized Branch Line Coupler With Open Stubs

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Prof.A.KARTHIKEYAN

VIT UNIVERSITY,SENSENANDU RAJENDRAN

11MCE 0052


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OBJECTIVE To design a miniaturized branch line coupler which can

operate at 2.45ghz

The topology of the circuit is designed using novel designof T-model approach with open stubs with high-low

impedances

The miniaturized branch-line coupler can be fabricated

with a low-cost FR4 substrate as a platform , producingsignificant reduction by more than 64.21% compared to

the conventional coupler on inexpensive board


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Introduction The branch-line coupler can be used as a power divider,

combiner or a part of mixer in microwave integrated

circuits

The coupler employs a quarter-wave length transformers

to develop a simple square-shaped connfiguration that is

used for power dividing or power combining functions

At lower frequencies, the size of conventional branch lineis exceedingly large in printed circuit


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Its physical size is relatively determined by the wavelength

which is large at lower frequency, and invariably affects

the dimension of quarter-wavelength (/4) transmissionlines used.

portable devices require components with compact size

and less cost features.

high performances, compact size and low cost are often the

stringent requirements to fulfill the demand of modernmicrowave communication systems


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HIGHLIGHTS OF THE PROPOSED

COUPLER open stubs with low and high impedances is introduced

and applicable to shrink the length of the transmission line

and invariably the dimension of the branch line coupler

the concept design of T- model and /4 model as

introduced respectively

the proposed novel technique which combines high and

low impedance in order to miniature size achieves greaterreduction of 64.21% compared to conventional ones.


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COUPLER STRUCTURE


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The dimensions of the open stub high and lowtransmission lines are derived using the electromagnetic

simulator AWR Tool

Both side of through and shunt arm of the couplers werebuilt on FR-4 substrate with permittivity, permeability, losstangent and heights are 4.7, 1, 0.019 and 0.8 mm,

respectively. The length of fabricated shunt line of branch-line coupler

is 10 mm, which offers about 41.1% reduction from theconventional shunt arm line of conventional coupler

These high impedence lines are dually located at the left

and right side of the design architecture of the coupler

circuit.


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CIRCUIT SCHEMATIC


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RESULT &ANALYSIS


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the -10 dB bandwidth of conventional design yield of

23.02% cover from 2.13 GHz to 2.68 GHz

the miniaturized size branch-line coupler, 22.08% of

bandwidth percentage cover frequencies 2.23 GHz to 2.78

GHz

It illustrates that only slight percentage difference between

the conventional and miniaturized size design


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CONCLUSION the proposed miniaturized one were designed, simulatedand fabricated at the frequency of 2.45 GHz.

both couplers can be etched on the same FR4 substrate. Thesize reduction of the proposed design is 64.21% withcomparable performance as that of the conventional branchline coupler.

The ease of design using standard etching process

makes the fabrication of the miniaturized coupler simpler and

with low cost. This prototype can be integrated into thedesign of microwave or millimeter-wave integrated circuits

where the compactness of components is crucial.


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FUTURE SCOPE Can be used in communication equipments which

require good performance at low cost

Broadband applications in the internet

Useful in digital broadcasting networks


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REFERENCES

1. Maas, S. A.,Microwave Mixers, Artech House, Norwood, MA,

1986.

2. Riblet, G. P., A directional coupler with very flat coupling,"IEEE

Trans. Microw. Theory Tech., Vol. 26, No. 2, 70-74, Feb. 1978.

3. Banba, S., T. Hasegawa, and H. Ogawa, Multilayer MMIC

branch-line hybrid using thin dielectric layers,"IEEE Microw.

Guided Wave Lett., Vol. 1, No. 11, 346-347, Nov. 1991. 4. Muraguchi, M., T. Yukitake, and Y. Naito, Optimum design of 3-

dB branch-line couplers using microstrip lines,"IEEE Trans.

Microw. Theory Tech., Vol. 31, No. 8, 674-678, Aug. 1983.


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5. Lin, C. T., C. L. Liao, and C. H. Chen, Finite-ground coplanar-waveguide branch-line couplers,"IEEE Trans. Microw. Wireless

Compon. Lett., Vol. 11, No. 3, 127-129, Mar. 2001. 6. Weng, L. H., Y. C. Guo, X. W. Shi, and X. Q. Chen, An overview

on defected ground structures," Progress In ElectromagneticsResearch B, Vol. 7, 173-189, 2008.

7. Caulton, M., B. Hershenov, S. P. Knight, and R. E. Debrecht,

Status of lumped elements in microwave integrated circuit- presentand future,"IEEE Trans. Microw. Theory Tech., Vol. 9, No. 7, 588-599, Jul. 1971.

8. Chiang, Y. C. and C. Y. Chen, \Design of a wide-band lumped-element 3-dB quadrature coupler,"IEEE Trans. Microw. TheoryTech.,

Vol. 49, No. 3, 476-479, Mar. 2001. 9. Hirota, T., A. Minakaw, and M. Muraguchi, Reduced-size branch-

line and rat-race hybrids for uniplanar MMIC's,"IEEETrans. Microw.Theory Tech., Vol. 38, No. 3, 270-275, Mar. 1990.

Miniaturized Branch Line Coupler With Open Stubs

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