Interferometry using Wilkinson Power Divider/Combiner

[Andrew Thornett]

Hi All,

At the Eastern Conference it as mentioned that the Wilkinson Power Divider/Combiner could be used as part of a radio interferometry system.

I looked up this device in Wikipedia and it says:

"In the field of microwave engineering and circuit design, the Wilkinson Power Divider is a specific class of power divider circuit that can achieve isolation between the output ports while maintaining a matched condition on all ports. The Wilkinson design can also be used as a power combiner because it is made up of passive components and hence is reciprocal. First published by Ernest J. Wilkinson in 1960,[1] this circuit finds wide use in radio frequency communication systems utilizing multiple channels since the high degree of isolation between the output ports prevents crosstalk between the individual channels."

Can someone explain to me why this device is useful in am interferometer?

Many thanks,

Andy

[Robert Hamers]

I’m only guessing, but a lot of passive devices like this can also be operated in reverse.  So perhaps the Wilkinson Power Divider can also be used to combine two signals, essentially operating in reverse ?

bob

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From: 'Andrew Thornett' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Date: Friday, August 7, 2026 at 5:49 PM
To: 'Dr. Rich Russel' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Subject: [SARA] Interferometry using Wilkinson Power Divider/Combiner

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[Marcus D. Leech]

On 2026-08-07 19:16, Robert Hamers wrote:

I’m only guessing, but a lot of passive devices like this can also be operated in reverse.  So perhaps the Wilkinson Power Divider can also be used to combine two signals, essentially operating in reverse ?

bob

Most passive devices like this have reciprocity.   Using a simple combiner, you can build an adding interfeometer.

You can get fancier, and make a "differential interferometer" with a pair of such devices and two receive chains--see our (very old now) article here:

https://www.ccera.ca/papers/rtlsdr-based-software-defined-radio-alternative-to-switched-radiometers-for-continuum-radio-astronomy/

To view this discussion visit https://groups.google.com/d/msgid/sara-list/PH0PR05MB759009EDC48E0DED679B14B7A1D12%40PH0PR05MB7590.namprd05.prod.outlook.com.

[Steve Hallman]

Hi Andrew;

The Wilkinson Combiner/Divider can be used in a type of Interferometer called an "Adding Interferometer", which can be configured to combine the analog signals from multiple antennas to feed a single SDR.

I plan to present the results of my latest project titled "Building A Discovery Dish Interferometric Array", where I've used a Wilkinson Combiner, at the next SARA meeting 

Steve H

P.S. I'd be happy to present at your BAA meeting also, if that would be a fit for your group

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