Tag Archives: Magnetic Loop Antennas

LZ1AQ Evaluates Impact of the Height Above the Ground on Mag Loop Performance

Source: LZ1AQ

Many thanks to SWLing Post contributor, Harald Kuhl (DL1AX), who shares the following article on LZ1AQ’s website:

Published on: 2018/11/20, Rev. 1.0 July 2018, Rev. 1.1 Nov 2018

Author: Chavdar Levkov LZ1AQ

Setup

Two identical small loops were placed one above the other according to Fig.1. One of the loops is very low – almost on the ground. The other one is placed at height which usually is used by the loop users. Two AAA-1C wideband active antenna amplifiers were used. Their gain difference was not more than 0.3 dB. The feeder was FTP cable each 20 m long. No cable baluns were used. The outputs were connected through two way antenna switch to a SD RX (Perseus). I used a measurement technique described in – A Periodic Switching Technique to Compare Receiving Antenna Performance in the Presence of Strong Fading. This is a precise method to compare two receiving antennas with real sky wave signals and the resolution can be less than a decibel. The idea is to switch periodically between two antennas and to estimate their difference on a calibrated graphic strength meter of a SD radio.[…]

Click here to read the full article.

I’ve often assumed height had little effect on the performance of an HF loop antenna–this evaluation seems to support that theory. Thanks for sharing this, Harald!

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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! 

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Using amplified loop antennas with portable radios?

SWLing Post contributor, Klaus Boecker, sports a homebrew magnetic loop antenna on his balcony in Germany.

Many thanks to SWLing Post contributor, Marty, who writes:

I have a question about loop antennas; specifically which type is “better,” passive magnetic loops or active electric loops?

I know, “It depends.”–?

I live in a ground-floor apartment, with a small porch, lots of RFI and restrictions against visible antennas. Also there are no trees within 75 ft of my porch, which faces on a parking lot. My radio is a Tecsun PL-660, which works okay inside with my 10-ft bare wire antenna hidden on the porch.

With a loop antenna, I’d like to mount the antenna on the porch at night and have a remote tuner/control inside because it’s very hot n humid here in Louisiana even after dark.

No doubt there are a number of magnetic loop antennas that could serve you well in your situation, Marty.

To answer your first question, though, you should search for a wideband amplified loop antenna since you’re only concerned with receiving.

Passive loops are great antennas on the shortwave bands–and easy to build–but they best serve ham radio operators who wish to transmit. Passive loops typically have a very narrow bandwidth that requires the operator to constantly tune the antenna when they tune the radio a few kHz. Most amplified wideband loops need no separate tuning mechanism.

Last year, I posted an article about choosing the right loop antenna for situations like yours where one has limited installation options.

Click here to read : Shortwave antenna options for apartments, flats and condos

Portables and amplified loops?

I do hesitate to encourage you to invest in an amplified loop antenna when your only receiver is a Tecsun PL-660. Some portables don’t handle amplified antennas well–they can easily overload and I imagine you can even damage the front end of the receiver.

I’m well aware, however, that there are a number of readers here who do couple their portable radio to an amplified loop. I have connected a number of portables to large wire antennas and found they could easily handle the extra gain, so I imagine an amplified loop would perform as well; the Sony ICF-SW7600GR, Tecsun S-8800, and Sangean ATS-909X come to mind.

But the PL-660 is a hot little receiver even with the built-in telescopic antenna–I’m not sure if amplification would help or hinder.

Please share your experience

This is where I hope the amazing SWLing Post community can pitch in and help us out here!

Does anyone here regularly connect their PL-660 to an amplified loop antenna? If so, what model of antenna are you using? Are there other portables out there that you regularly connect to amplified loops? Please share your notes, thoughts and experience in the comments section.

Thank you in advance!


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Inexpensive wideband amplified mag loop receiving antenna on eBay

Many thanks to SWLing Post contributor, Ola, who shares a link to this inexpensive mag loop antenna on eBay.

I have no clue if this antenna performs as well at all, but the price is certainly much lower than its competition at $47.99 US.

It appears you’ll need to supply your own dielectric center support  for this loop–a length of PVC would do the trick.

Copycat–?

I don’t like the fact this manufacturer has chosen the name “Mega Loop Active” for their antenna as the name is too similar to Bonito’s “MegaLoop FX Active.” I don’t like the confusion that could create, so I would hope this Chinese manufacturer would change this in time.

To be very clear, this product has no affiliation with Bonito and I certainly would not expect the quality or performance you would get from a Bonito product. Bonito products are pricey, but they’re design and manufactured in Germany and set benchmarks in terms of performance and quality. I’m a big believer in “you pay for what you get.”

I suppose though if you’re just looking for a cheap antenna to test, this one is quite inexpensive. Just know that it is not a Bonito MegaLoop, despite the similarities in product name! 🙂

Click here to view on eBay.

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