couple line coupler

7/27/2019 Couple Line Coupler

1/14

Coupled Line CouplGROUP 4: Tan Ter Wei, Syafiq, Huzairie, Nazirulazim, Fong Mei L


2/14

Introduction

Couple Line Coupler

Two transmission lines in proximityto eachother will couple power from one line intoanother.

Modify the electromagnetic fields (and thusmodify voltages and currents) of the

propagating wave, and therefore alter thecharacteristic impedance of thetransmission line.


3/14

Even mode-currents in the strip conductors are equal in amplitude and in the same direction.

-electric field has even symmetry about the centre line, no current f lows between the two strip

conductors.

Ce=C11=C22

-Characteristic impedance

Where

Odd mode-currents in the strip conductors are equal in

-electric field has odd symmetry about the centre line, a

conductors.

C0=C11+2C12=C22+2C12

Characteristic impedance


4/14

Problem Statement

To propose a suitable specification of coupled-line cou

wireless transceiver working from 2.4GHz to 2.4835GHz.

To derive the s-parameters components from the comp

of Ze & Zo to obtain the optimal value.


5/14

Design TheoryDESIGNRULE

1. Electrical length

cot 0l = 0

0l = /2

l= 0 /4

2. Geometric mean equal to Z0

Since it is matched, S11 = 0and S41 = 0.

If S11 = 0, Z0e= Z0

o.

By implementing the design rules,

, where c is the coupling coefficient.

Rewrite S31

Given Z0eZ0

o= Z02,


6/14

By using the S11, S21, S31 and S41 found from above slide, we can substitute

into the scattering matrix below:

From the scattering matrix, we can see that it is an ideal symmetric directional coupler.

The even and odd characteristic impedances can be found

using the equations below:

Z0e= Z0[(1+c)/(1-c)

1/2]

Z0o= Z0[(1-c)/(1+c)

1/2]


7/14

Design Procedure

CLIN (IdealCoupler)

SetParameters

SimulateTuning

(ZE = 120.7

)

Update

Schematics

MCLIN (Non-Ideal

Coupler)

Lin

SimTuning

(W = 0.653 mm)

UpdateSchematics


8/14

Coupler base architecture des


9/14

Results & Observations

Figure (1): Schematic using CLIN (Ideal CouplerLine

Figure (2): dB graph for S21 and S31 wit


10/14

Figure (1) shows the s

By using this schemat

and Zo values to be u

Figure (2) shows the d

In order to get equal magnitudes(dB) need

graph, both S21 and S

3.021dB respectively

Ze needs to be tuned

equal.

Figure (3) shows the d

after the Ze is tuned. S31 are almost equal,

-3.011dB respectively

tuned value of Ze, the

output ports are equaFigure (3): dB graph for S21 and S31 after tuning Ze


11/14

Figure (4): Schematic using MCLIN (Microstrip Coupler Line)


12/14

Figure (5): dB graph for S21 and S31 without tuningthe width of microstrip line

Figure (6): dB graph for S21 and S31 awidth of microstrip line

Figure (4) shows the schematic by using MCLIN. By using this schematic, the values of Ze and Zo are ob

schematic.

Figure (5) shows the dB graph for S21 and S31. For equal power output, the magnitudes(dB) need to be

both S21 and S31 are -3.026dB and -3.097dB respectively and they are not equal. The microstrip width

for S21 and S31 to be equal.

Figure (6) shows the dB graph for S21 and S31 after W is tuned. After tuning, S21 and S31 are almost eq3.061dB and -3.060dB respectively. This means that the output power at the output ports are equal.


13/14

Discussion

1. For ideal coupled line coupler, the conditions below are given:

Lossless & Reciprocal Matched

Symmetrical

2. We are designing a coupled line coupler with equal power outputs.

Goal - obtained equal values of S21 and S31 in magnitude (dB).

3. By using CLIN, we tuned the Zeto get the approximate Zevalue that we should use in M

design.

4. We choose to tune, the width rather than the spacing between the coupler because th

the most effect on the microstrip.


14/14

The Ze& Z

ocan be easily obtain from the simulation using appropriate t

formulas. We obtain the suitable value for both via tuning method.

The network design is set to be matched, in other words, S11 is zero

The symmetrical properties of the network implies that S22, S33, &

equals to 0. So, we can conclude that this directional 4-port network is lo

reciprocal network.

Therefore, the s-matrix is accept

Conclusion

couple line coupler

Documents