# Designing a broadband matching network

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#### cooleyn

##### Member level 1

First of all, bode-fano rule should be investigated that to what extent we can do for this broadband matching. The reflection coefficient should meet : |Tao|min=exp(-pi*Q0/Qs). In your case, assume 10%
bandwidth achieve for matching, Q0=10, For RLC series source impedance, Qs=sqrt(L/C)/R ~=40.
so |Tao|min=exp(-pi*Q0/Qs)=0.456, in log field, |Tao|(dB)>=-6.82, so for -10dB return loss task is impossible. For 5% matching bandwdith, |Tao|(dB)>=-13dB, which is reasonable for implement. For broadband matching , you can try
Genesys matching synthesis tool which is a good tool
for automatic matching.

### bingjiang99

Points: 2

#### bingjiang99

Yes, this is the theoritical answer that I am looking for. I totally forgot it. Thanks.

I can't go with the automatic matching. It is too expensive for me to implement.

cooleyn said:
First of all, bode-fano rule should be investigated that to what extent we can do for this broadband matching. The reflection coefficient should meet : |Tao|min=exp(-pi*Q0/Qs). In your case, assume 10%
bandwidth achieve for matching, Q0=10, For RLC series source impedance, Qs=sqrt(L/C)/R ~=40.
so |Tao|min=exp(-pi*Q0/Qs)=0.456, in log field, |Tao|(dB)>=-6.82, so for -10dB return loss task is impossible. For 5% matching bandwdith, |Tao|(dB)>=-13dB, which is reasonable for implement. For broadband matching , you can try
Genesys matching synthesis tool which is a good tool
for automatic matching.

#### VSWR

The Bode-Fano Criterion

### bingjiang99

Points: 2

#### luqing

##### Newbie level 6
pi network matching s11

There are many methods for broadband match,such as RFM.Recently I have been designed an matching network with that method.But I must say that we cannot get very satisfying results ,which depends on the impendance data.
BTW,cooleyn,can you tell me what is Genesys matching synthesis tool,can you send me some materials about that tool.And do you use tool Mosaic for matching network.what about this tool?

### bingjiang99

Points: 2

#### bingjiang99

high q and broadband matching program tool

luqing,

do you have articles about RFM? I would like to give it a shot.

Thanks,

luqing said:
There are many methods for broadband match,such as RFM.Recently I have been designed an matching network with that method.But I must say that we cannot get very satisfying results ,which depends on the impendance data.
BTW,cooleyn,can you tell me what is Genesys matching synthesis tool,can you send me some materials about that tool.And do you use tool Mosaic for matching network.what about this tool?

#### VSWR

Title: Design of a Matching Network for Dipole Antennas

Abstract: The input impedance of an antenna is highly dependent on the frequency range in which it operates. For an electrically small antenna to operate in a broad frequency range, the antenna must be properly matched. This thesis presents the design of a matching network for a 1-meter monopole antenna, operating over 30-90 MHz using the real frequency method (RFM). It outlines the mathematical steps needed to determine the equalizer function, which ultimately leads to the circuit design. The goal of the RFM, given the real frequency data, is to optimize the Transducer Power Gain (TPG), and minimize the reflection coefficient or power lost due to the impedance mismatch. Complete design including network realization is given.

### bingjiang99

Points: 2

#### bingjiang99

high q and broadband matching program tool

VSWR,

thank you very much.

VSWR said:
Title: Design of a Matching Network for Dipole Antennas

Abstract: The input impedance of an antenna is highly dependent on the frequency range in which it operates. For an electrically small antenna to operate in a broad frequency range, the antenna must be properly matched. This thesis presents the design of a matching network for a 1-meter monopole antenna, operating over 30-90 MHz using the real frequency method (RFM). It outlines the mathematical steps needed to determine the equalizer function, which ultimately leads to the circuit design. The goal of the RFM, given the real frequency data, is to optimize the Transducer Power Gain (TPG), and minimize the reflection coefficient or power lost due to the impedance mismatch. Complete design including network realization is given.

#### Jim cage

##### Full Member level 3

The problem with using double L matching network is that it is hard to tune it. since Cap and Inductors doesnt acts as true capacitors and inductors this task will be very difficult. It will be advised to use transmission lines or paralell stubs to tune your circuit.

#### luqing

##### Newbie level 6

hi,VSWR
can you tell me how to download the article"Design of a Matching Network for Dipole Antennas"
Thanks a lot!

To:bingjiang99
I am sorry for my late reply and I have no articles about RFM.Here I just have a book in which there is a chapter mentioned that.

### bingjiang99

Points: 2

#### bingjiang99

Thank you luqing. I found some papers from IEEE.

luqing said:
hi,VSWR
can you tell me how to download the article"Design of a Matching Network for Dipole Antennas"
Thanks a lot!

To:bingjiang99
I am sorry for my late reply and I have no articles about RFM.Here I just have a book in which there is a chapter mentioned that.

#### khaled fayed

##### Newbie level 3

Hi, thanks for this important topic! From my experience with matching networks, I suggest that u use AWR (Microwave office). it is very helpfull. u can use its optimizer to design the matching network that u want easily. put multiple sections of L and C. then by setting ur goals and running the optimizer (optimize the L, C and Q factors), u can know what is the Bode-Fano limitations for ur case

### bingjiang99

Points: 2

#### bingjiang99

Thank you.

khaled fayed said:
Hi, thanks for this important topic! From my experience with matching networks, I suggest that u use AWR (Microwave office). it is very helpfull. u can use its optimizer to design the matching network that u want easily. put multiple sections of L and C. then by setting ur goals and running the optimizer (optimize the L, C and Q factors), u can know what is the Bode-Fano limitations for ur case

### bingjiang99

Points: 2

#### IamnotJunk

##### Member level 1

Have you used spice to simulate?

#### bingjiang99

Yes.

IamnotJunk said:
Have you used spice to simulate?

##### Member level 1

Dear luqing
you can study more about real frequency technique at a book named "solid state microwave amplifier design" written by T.T.Ha, although it is not an easy method.

### bingjiang99

Points: 2

#### bingjiang99

Thanks

Dear luqing
you can study more about real frequency technique at a book named "solid state microwave amplifier design" written by T.T.Ha, although it is not an easy method.

#### Bibhu166

##### Newbie level 5

Hi,
Yeh, matching is what you have said.In this case, it will be very narrow bandwidth as Q is so high.The power will be tranfered when it is matched to 50 ohm, .sO, in band the input resitance should be near about 50 ohm.Witht this low resitance and high Q it is difficult. You may refer Pozar how to match with another LC element.You may match to some intermidiare load.
Regards,
Bibhu

derek_lkm said:
Hi all,

Find this topic interesting, however i not really sure why the matching is diffcult. From my basic understanding, it would just be made with the movement on the smith chart and its corresponding passive values. I understand that for maximum voltage transfer, we would like a large load, but since we are mentioning about Sparameters, we are interested in power transfer. As long as the matching is done up we should get the maximum power transfer. Maybe i'm wrong or i have taken enough factors into considerations? Would like to hear the views of the gurus out there.

Thanks and wish everyone have a nice day.

Regards
Derek

##### Member level 3

I found a paper on broadband martching simulation.

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### bingjiang99

Points: 2

#### bingjiang99

Thanks.

I found a paper on broadband martching simulation.