Can someone ID this Singer Eaton magnetic loop antenna found on eBay?

Many thanks to SWLing Post contributor, Dan Robinson, who shares a link to this 31″ Singer Eaton loop antenna found on eBay.

The seller knows nothing about this antenna, but did provide some detailed photos of the connector and product information sticker:

This loop obviously came from US government inventory based on the sticker. It looks to be quite robust and sports one of the balanced antenna connectors found on rigs like the Hammarlund SP-600. I’m guessing this loop might be fixed-frequency as I see no tuning section with a variable capacitor.

Can any SWLing Post readers shed a little light on this loop?  Have you ever used one? Please comment! 

Spread the radio love

6 thoughts on “Can someone ID this Singer Eaton magnetic loop antenna found on eBay?

  1. Tim Hague

    These loops were used for LF E field measurement in EMC Labs back in the day. Singer-Stoddart produced manually tuned EMI measuring receivers.
    Full specs are available on the web. Probably 30+ years old

  2. Ken

    Interesting a Twinax connector that is an obsolete but very good RF connector. They were used on Radios like the R390A/URR. The male counter part the RS-R21 connector is readily available.

    1. Andrew

      If it’s the one I think it should have a balanced impedance of 95Ohms, so one will probably need a transformer to use it, plus, as “13dka” pointed out, that antenna was built to work in the 30Hz to 10Khz range … so I’m not sure how much it may be useful with a “regular” receiver 🙂 Anyhow, the antenna part number matches loop antennas built under several brands; AILTECH, EATON, SINGER, TEGAM; also, seeking around, found an alternative part number for that 90117-3, here

  3. 13dka

    The part and NSN numbers indicate that this is one of the accessory antennas for the Stoddart Aircraft Radio NM-40A ELF/VLF field intensity meter/receiver or a follow-up design. That would mean it was built for 30Hz(!)-15kHz and contains 11 wire windings inside the shield loop.

    The loop can be seen further down this page:

    I’d probably want to check this part with a Geiger counter tho, this .pdf describes how 3 of those loops were used in a Canadian EMP nuke test setup 🙂 :


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.