{"id":53711,"date":"2022-08-18T08:00:27","date_gmt":"2022-08-18T12:00:27","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=53711"},"modified":"2023-01-11T13:56:43","modified_gmt":"2023-01-11T17:56:43","slug":"introducing-the-amazing-sula-an-affordable-unidirectional-dx-grade-loop-antenna-that-you-can-build","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2022\/08\/introducing-the-amazing-sula-an-affordable-unidirectional-dx-grade-loop-antenna-that-you-can-build\/","title":{"rendered":"Introducing the amazing SULA: An affordable unidirectional DX-grade loop antenna that you can build!"},"content":{"rendered":"

\"\"<\/a>Many thanks to SWLing Post<\/em> contributor extraordinaire, 13dka<\/a>, who brings us a three part series about the new SULA homebrew antenna project. This first article describes this affordable antenna and demonstrates its unique reception properties. The second article will focus on construction notes. The third and final article will essentially be a Q&A about the SULA antenna. All articles will eventually link to each other once published.<\/strong><\/p>\n

This wideband unidirectional antenna is an <\/b>outstanding and innovative<\/em> development for the portable DXer. I love the fact that it came to fruition via a collaboration between Grayhat<\/a> and 13dka<\/a>: two amazing gents and radio ambassadors on our SWLing.net discussion board<\/a> and here on the SWLing Post. So many thanks to both of them!<\/b><\/p>\n

Please enjoy and share SULA Part 1:<\/strong><\/p>\n

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Introducing the Small Unidirectional Loop Antenna (SULA) 1-30MHz<\/h1>\n

A small and simple, unidirectional and DX-capable loop “beam” for SWLs!<\/h3>\n

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by 13dka<\/strong><\/p>\n

In early June, Andrew (grayhat), SWLing Post<\/em>‘s resident antenna wizard suggested a variation of the “cardioid loop” on the SWLing Post<\/em> message board<\/a>: The original “cardioid loop” is a small loop receiving antenna deriving its name from a cardioid shaped (unidirectional) radiation footprint. The design is strikingly simple but it has a few downsides: It relies on a custom preamp, it needs a ground rod to work and it is unidirectional only up to 8 MHz.<\/p>\n

Andrew’s version had the components all shuffled around and it did not only lose the ground rod, it also promised a nice cardioid pattern over the entire shortwave, from a small, diamond shaped loop. Wait…what? It can be made using parts available on Amazon and your DIY store:<\/p>\n

You need some 3m wire and PVC tubes to create a support structure to hold the wire, a 530 Ohm resistor and a 9:1 balun like the popular “NooElec One Nine”. Since it’s a “lossy” design, adding a generic LNA like the NooElec “LANA HF” would help getting most out of it. When you put that all together you have what sounds like an old shortwave listener’s dream: a small, portable, tangible, and completely practical allband shortwave reception beam<\/em> antenna with some more convenient properties on top, for example, it is a bit afraid of heights.<\/p>\n

That sounded both interesting and plain crazy, but the .nec files Andrew posted were clearly saying that this antenna is a thing now. Unfortunately Andrew suffered a little injury that kept him from making one of those right away, I on the other hand had almost all the needed parts in a drawer so I ended up making a prototype and putting it through some of its paces, with Andrew changing the design and me changing the actual antenna accordingly, then mounting it upside down. Let me show you around:<\/p>\n

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