Over on his YouTube channel Frugal Radio has been testing his YouLoop passive magnetic loop antenna on VLF and LF reception with his Airspy HF+ Discovery. In the video Frugal Radio browses the VLF & LF spectrum, making note of some interesting signals, and showing how well the combo receives.
The YouLoop is a low cost passive loop antenna for HF and VHF. It is based on the Möbius loop design which results in a high degree of noise cancelling. However the main drawback is that it is a non-resonant design, which means that it needs to be used with ultra low MDS receivers like the Airspy HF+ Discovery. We have YouLoop stock available in our shop for $34.95 with free worldwide shipping.
Airpsy YouLoop passive antenna review on VLF & LF with an HF+ Discovery and SDR# during storms!
The YouLoop is a low cost passive loop antenna for HF and VHF. It is based on the Möbius loop design which results in a high degree of noise cancelling. However the main drawback is that it is a non-resonant design, which means that it needs to be used with ultra low MDS receivers like the Airspy HF+ Discovery. However, a high performance HF pre-amp will be available in the future which will allow it to work well with other radios too.
In his video Robin tests the YouLoop on the HF bands with an Airspy HF+ Discovery and he demonstrates excellent noise free reception from his location. In terms of his setup he notes:
I am running Spyserver on a 10 year old Windows 7 laptop in the loft. The same laptop is also running 3 x SDRSharp instances (following 2 digital trunking systems). It runs 4 x simultaneous Zello instances each providing a high quality audio feed to my Network Radio / phone.
In terms of noise-creating equipment nearby, there is
a second laptop used for other duties
a Pi 3B used for ADS-B reception, feeds & a second instance of spyserver
a Pi 3A with MMDVM module performing as a hotspot
a Motorola HT charger
5 x base station scanners
This means there are 10 x switched mode power supplies constantly running, as well as 4 x 24/7 WiFi devices.
All this equipment is within 10ft of the YouLoop antenna, was one of my primary reason for choosing a passive loop.
Since making the video, cable clips have been added provide support to the antenna which means it is now in the correct shape of a loop. That means I am unable to rotate the antenna to make use of the nulls when receiving. However I am very pleased with the performance based on the location, noisy environment, and frugal pricing :-)
$35 Airspy YouLoop Passive Antenna Review : tested on HF using Airspy HF+ Discovery SDR
The Elektor SDR Hands-On-Kit is a low cost (€49.46) SDR learning package that makes use of the Elektor SDR Arduino shield which turns an Arduino microcontroller board into a 150 kHz to 30 MHz capable SDR receiver. It also comes with a book that teaches several basic SDR concepts.
Over on YouTube TechMinds has recently uploaded a video where he unboxes, constructs, and tests the kit using the free G8JCFSDR SDR software. TechMinds also notes that this SDR Shield can also transmit with 10mW of power, and that there is a tutorial included in the book that shows how to use the shield as a simple WSPR transmitter.
Elektor SDRShield - Hands-on Software Defined Radio Kit
We've recently seen a few submissions about a new low cost active magnetic loop antenna called the K-180WLA which sells for around US$50 - US$60 over on eBay and Aliexpress. While it appears to be very similar to the well known MLA-30 loop, it's main defining feature is that it's power feeder is battery powered via a built in Lithium ion cell which would make it useful for portable operation. It also advertises a wide usable frequency range of 0.1 - 180 MHz with an amplified gain of 20 dB. They note it can also be pushed up to 450 MHz with reduced gain of 8.9 dB. The battery run time or power draw is not advertised. They write:
The P.BOX feed box has a built-in 3.7V 18650 flat-head lithium battery with integrated power supply module. It is the only active antenna that does not require an external power supply and integrates a charge management chip. The MICRO USB charging port is compatible with the 5V charging head of Android phones. And charging cable, very easy to use.
UHF low-noise preamplifier is used. The gain flatness is very good within the ultra-wide operating frequency of 0.1-180MHZ. It provides a gain of about 20DB, even when working to 450MHZ gain, there is still about 8.9DB.
The receiving frequency covers long wave, medium wave, short wave, FM broadcasting band and VHF aviation band. The small ring diameter 55CM is simple to set up. It can be set up outside the window, balcony, terrace and roof. Lovers erected.
All the screws of the antenna are made of 304 stainless steel, and the preamplifier box is fully waterproof, which can be used for long-term outdoor wind and rain.
Suitable models include Desheng S-2000 PL-660 PL-880 ICOM R71E YAESU FRG-8800 and all short-wave receivers, especially for SDR receivers.
The antenna is equipped with a dual SMA male adapter cable, an SMA to 3.5 plug adapter cable, and an S2000 BNC adapter, which means that your radio can be used with SMA female, BNC, and 3.5 jacks. Requires additional accessories. Receivers and radios with other interfaces need their own adapters.
Over on the SWLing (Short Wave Listening) Post blog Thomas has just uploaded his review of the YouLoop in a post titled "The Airspy Youloop is a freaking brilliant passive loop antenna". If you weren't aware, we are currently selling this loop in our store for US$34.95 incl. free worldwide shipping to most countries. Sales are currently in pre-order as our first batch of units ordered sold out within a day, but we're soon going to receive the second batch in the next few days.
Thomas is a seasoned shortwave listener who has used many antennas, and in the review he notes that he is extremely impressed with the performance. In his review he tests the antenna in a location that is swimming with RFI and places the loop in the middle of a bedroom. Although the situation is not ideal, Thomas was surprised at the number of signals he was able to receive.
To work properly the YouLoop requires a low noise figure radio like the recommended Airspy HF+ discovery, but Thomas notes that he's also had excellent success with the SDRplay RSPdx running in HDR mode.
A few days ago we posted about our release of the first batch of YouLoop passive HF/VHF loop antenna kits. We underestimated the demand and sold out of kits in less than a day! We now have a second batch currently being manufactured and it should be ready to ship out in about a week from now (late March/early April).
You can currently pre-order this item from our store, and we will ship it out as soon as the stock hits the shelves on our warehouse. For this product we are focusing on non-US customers and US customers can purchase locally from airspy.us. Though we will still fulfill US orders if you want to order from us instead.
If you are interested in further information, search YouLoop on Twitter to see a bunch of new tweets about people talking about and demonstrating this antenna design.
We have recently been able to obtain a small number of YouLoop HF/VHF portable receive only passive antennas that were produced by the owner of Airspy. The YouLoop is available in our store priced at US$34.95 including free worldwide shipping. It comes with the balun "tee" connector, coax inverter, 2x 1m semi-rigid coax cables for a ~60cm loop, and 1x 2m semi-rigid coax for the feedline. Note that US customers may wish to purchase from airspy.us as they have local US stock. We are focusing on non-US orders for this product and we only have very limited stock at the moment - UPDATE: Now out of stock. We have reordered more and should be back in stock by end of March.
If you don't know what a "YouLoop" is, it is a simple passive magnetic loop antenna design which consists of a ring of coax cable and a low loss 1:1 or 4:1 balun. The design was recently popularized by Youssef (prog) the owner of Airspy, and he has put up a page explaining how the design works here. Many users on Twitter have been reporting good results with HF reception with the design. It appears to be especially useful in urban environments where there is lots of local noise.
Left Discovery with YouLoop Antenna, Rigth Discovery with HF Hoxin Vertical Antenna.
Same configuration in sdr#, both in roof with 25m RG213 cable.
A lot of noise in the vertical antenna, Barcelona noisy city. pic.twitter.com/NNYdpsmNTo
Being passive, it has no amplification and so it works best with a low noise SDR like an Airspy HF+. However we have also found decent results with SDRplay SDRs, and a standard RTL-SDR Blog V3 running in direct sampling mode, although RTL AGC mode needs to be turned on for an extra boost. Improved results can be obtained by using a low cost HF amplifier on the front end, and even our wideband LNA which is advertised as working down to 50 MHz still does actually give a decent boost from 5 MHz and up.
Also the design has some advantages in that it has very low electrical interference pickup, and has no electronics that can overload from signals that are too strong. Overloading from strong signals is something that can easily affect cheap magnetic loop antennas like the MLA-30, and even higher end loop antennas too. Being a magnetic loop, it also naturally filters out electric field interference which is extremely common in urban environments, and is the reason why e-field antennas like miniwhips often perform poorly.
The antenna is designed to be extremely portable, being lightweight and easy to assemble/disassemble. As such it is not designed to be weatherproof, so if you do decide to mount it permanently please make use of weatherproofing tape.
Unlike fixed magnetic loops, the YouLoop design is also easy to experiment with. By using longer coax cables you can easily create a larger loop which can result in stronger signals. We found that replacing the 1m loop cables with 2m lengths gave quite nice results for us. If you have the space you could try even larger loops too.
The design also doubles as a great VHF antenna with reception up to 300 MHz possible when used in a folded dipole configuration. To do that, simply flatten the loop into a dipole shape.
Finally, if you prefer the YouLoop can also be constructed by yourself. The Twitter post below shows the basic design. Search Twitter for "YouLoop antenna" for more discussion on the design too.
Thank you to Jean-Marie Polard (F5VLB) for letting us know about his work in creating underground "earth probe" antennas that work for both RX and TX between 0 - 14 MHz, and are especially good at VLF and below. He writes:
Can't install an antenna at home? Madame refuses the masts, taut son? One solution, The Earth probes antenna.
Our group (https://www.facebook.com/groups/earthprobes/) started in January 2019. At first everyone made fun of me, the professionals called me crazy and today with more than seven hundred members, we installed underground antenna systems and the results are there.
Between 0 and 14MHz, in transmission and reception, it works!
This system dates from 1914/1918 but has been brought up to date.
It doesn't take much to get started, just the urge to try.
To access the Earth Probes and VLF.ULF.ELF groups you'll need a Facebook account. The groups contain a number of research papers documenting the concept, and the photos section. From the photos, an earth probe antenna appears to consist of two long grounding rods spread over a distance, or a grounding rod and long buried wire, combined with a balun.