Compact Wilkinson Example 3: the Kang power divider

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New for August 2024.  We split the content below from this page which was getting too long.  Now each compact Wilkinson has its own page:

Example 1: Webb power divider

Example 2: Scardelletti power divider

Example 3: Kang power dividers

Example 3: Kang splitter

This technique was described by In-Ho Kang and Jin-San Park in their July 2003 Microwave Journal article entitled A Reduced-size Power Divider Using the Coupled Line Equivalent to a Lumped Inductor. It was pointed out to us on the Microwaves101 message board.

Update November 2006... we finally simulated the Kang splitter. Thanks to David from down under for sending us the article!

What Kang and Park figured out is that you can fake the quarterwave section using a coupled line that is shorted on two ports, with a pair of capacitors.

Before we describe Kang's splitter, let's look at a conventional Wilkinson realized using microstrip on 10 mil alumina. The next two images show the ADS schematic and its response:

Compact Wilkinsons

Compact Wilkinsons

Notice that a quarterwave section at 10 GHz is 120 mils.

The layout below represents about 10 minutes worth of work, trying to get the Kang splitter to behave at X-band, using 10 mil alumina. As you can see, the coupled line section is far less than a quarter wavelength, in this case it is closer to 1/16 wavelength. Tradeoffs that can be made include the coupling factor (spacing between the arms), length and impedance of the coupled section, and the capacitor values. Note that C1 and C2 could be combined into one capacitor of double the value, but we like the symmetry as it is shown.

Compact Wilkinsons

 

Here's the response, it has NOT been fully optimized.

Compact Wilkinsons

More to come!