Coupler Design Question

• 0
I've been tasked with creating a 4-way coupler that has equal power in 4 ports.
There are other specifications but my first question comes from if I should use a rat-race, branchline, or some sort of hybrid model.
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Franklin, we need those other specifications to be able to recommend a model.
frequency band, acceptable loss in each path, acceptable isolation between output ports, power handling.
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Bandwidth is probably the most important question as some approaches are only good for narrow band.
Also, you should consider if the outputs need to have the same transmission phase...

Steve
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Thank you for responding and sorry for the lack of details,

The center frequency must be 1.575GHz, Insertion Loss <5dB, Isolation >20.0dB, Phase Balance at the output <5 degrees, VSWR over passband <1.5 : 1, amplitude Balance at output <1dB.

Since I last posted I have thought about doing a 4 output wilkinson power divider. I would love to know your thoughts
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Well I'll pay you \$100M to design a 4 way splitter with under 5 dB insertion loss.
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Seems like a lumped element solution might be possible at 1.5 GHz. Maybe "<5 dB insertion loss" means that the 5 dB in addition to 6 dB loss from the 4-way split.
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Attached is what I have so far using ADS.

My next step is to figure out where to go from here to reach the design specifications. How can I figure out what to change the widths and lengths of the lines to? And when I run my simulation and create my graphs, what should I be looking for within the S parameters? What should I be graphing together?
• 3
You need to make the lines 1/4 wave long at center frequency
You should plot S11, S22, S23 and S24. The rest of the parameters will be repeats of these due to symmetry. You can make a goal of -20 dB at band center for all of them.
The widths of the lines should correspond to 71 ohms. ADS should be able to calculate the line widths and quarterwave lengths for you.
That should get you started

This seems like a homework assignment...

Steve
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