Tagged: HF

Comparing Shortwave Antennas with an RTL-SDR and FT8 Monitoring

Eric had an inverted L and T3FD antenna set up in his backyard and he wanted to test both at the same time to see which received HF better overall. Rather than relying on subjective 'by ear' measurements he decided to use the digital FT8 mode as his comparison signal. FT8 is quite useful for this purpose as the decoded data includes a calculated signal-to-noise (SNR) reading which is a non subjective measure that can be used for comparisons. It also contains information about the location of the signal which can be used for determining the DX capability of the antenna. 

To perform the comparison he used two or our RTL-SDR Blog V3 dongles running in direct sampling mode, and also added an additional low pass filter to prevent excessively strong TV and FM signals from overloading the input. Each antenna is connected to it's own RTL-SDR, and a modified version of GQRX with remote UDP control is used to switch between multiple FT8 frequencies so that multiple bands can be covered in the experiment. WSJT-X is used for decoding the FT8 packets.

After logging SNR values for several days he was able to plot and compare the number of packets received by each antenna, the maximum distance received by each antenna. His results showed that his inverted L antenna was best in both regards. He then performed a relative comparison with the SNR readings and found that the inverted L performed best apart from at 14 MHz, where the T3FD performed better.

In further tests he also compared the antennas on which signal headings they were receiving best from. The results showed that Erics inverted L was receiving best from one direction only, whereas the T3FD received signals from more headings.

Eric's post includes full instructions on the software setup and also Python code which can be used to replicate his experiments. We think that this is a great way to objectively compare two types of antennas.

Antenna directionality measurements via FT8 received headings

The Silphase R1 SDR Receiver

Thanks to Thomas' SWLing Blog for bringing to attention the Silphase R1 SDR receiver. This is an upcoming high performance HF SDR receiver being manufactured in the EU by a Polish company called Silphase. The R1 appears to be targeting premium SWLer customers with a price of US$1199. However, they note that by the end of 2020 they will have a 25W transceiver option, and later a 100W transceiver option. The SDR is currently available for preorder only and the sign up form can be found at the bottom of their website.

The Silphase R1 comes with a 5" touch screen that shows a spectrum display, has dual VFO's, four speakers and a metal alloy enclosure. It also comes with a built in telescopic antenna, but external antennas can be connected with the F connector. The tuning range is just the HF bands from 0.1 - 30 MHz and the ADC resolution is 16 bits.

Rendering of the upcoming Silphase R1 HF SWLing SDR

Testing the YouLoop on VLF & LF Reception with an Airspy HF+ Discovery

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 Passive Loop Antenna Reviewed on HF Reception

Thank you to Robin from the "Frugal Radio" channel on YouTube for submitting his latest video which is a review of the Airspy YouLoop antenna that we currently have for sale on our store for $34.95 including shipping.

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

TechMinds: Hands on with the Elektor SDR Arduino Shield Learning Kit

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

The K-180WLA: A New Low Cost Battery Powered Active Loop Antenna

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.

    Note:

    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.

We've ordered a unit and plan to compare it against the MLA-30, Wellbrook and YouLoop (with optional HF amplifier that is to be released soon) in a future post. This loop is also being discussed over on the SWLing Post Blog.

The K-180WLA Loop Antenna
The K-180WLA Loop Antenna

The SWLing Post Reviews the YouLoop Passive Loop Antenna

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.

YouLoop Portable Passive Magnetic Loop Antenna for HF and VHF
YouLoop Portable Passive Magnetic Loop Antenna for HF and VHF

YouLoop Batch 2 Available for Pre-Order: Estimated Shipping in One Week

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.

YouLoop Portable Passive Magnetic Loop Antenna for HF and VHF
YouLoop Portable Passive Magnetic Loop Antenna for HF and VHF