Tagged: dipole

Using our RTL-SDR Blog Dipole as a V-Dipole for Receiving Weather Satellites

With our RTL-SDR Blog dipole antenna set, it is possible to use it in a "V-dipole" configuration to receive polar-orbiting weather satellites such as NOAA and Meteor at 137 MHz. More information on this can be found on our page at www.rtl-sdr.com/DIPOLE.

If you are after more visual instruction, "Baltic Lab" has uploaded a clear video on YouTube showing how to set the dipole leg lengths and angles correctly for weather satellite reception. 

We want to add that it is also important to remember to mount the antenna outdoors horizontally and in a north-south orientation with a clear view of the sky for the best results.

How To Build A V Dipole For Receiving Weather Satellites

Receiving Weather Images from NOAA Weather Satellites with an RTL-SDR Blog V4 and Multipurpose Dipole Antenna Kit

Over on YouTube Baltic Lab has uploaded a video showing how he was able to successfully use an RTL-SDR Blog V4 and the included multipurpose dipole antenna kit to receive images from polar-orbiting NOAA weather satellites.

In the video, Baltic Lab shows how to orient the dipole antenna in a "V-Dipole" shape which optimizes it for receiving from satellites. He also shows how to use a VNA to confirm that the telescopic elements on the dipole are extended to the correct length, noting that he was able to achieve a VSWR of less than 1.2 between the target frequencies of 135 to 138.1 MHz, with a near perfect match at 136.5 MHz.

He then demonstrates receiving the NOAA APT signals with his laptop, and successfully recovering the weather satellite image.

How To Receive Weather Images Directly from Space | NOAA Weather Satellites

Frugal Radio: Turning Scrap Wire into an Effective HF Dipole

In this weeks video Rob from his Frugal Radio YouTube channel shows us how he's turned an old piece of scrap electrical extension cord into an effective HF antenna for his Airspy HF+ SDR. The scrap wire is combined with a US$15 NooElec 9:1 balun which helps improve the impedance match of the antenna. He then stretches the dipole out through his backyard and then hooks it up to his Airspy HF+.

The results show good reception across the 20m, 80m, 40m amateur radio bands, as well as on HF ATC aircraft communications, US coast guard weather information broadcasts and the AM broadcast band.

I made an HF Dipole for free! Reception was good on my AirSpy HF+ Discovery SDR!

Frugal Radio: SDR Guide Ep 4 – Antenna Basics for SDR Beginners

In this episode of Frugal Radio's series of SDR beginners guide videos he discusses some antenna basics. He shows the most common types of antennas, provides several tips to help improve reception, and shows how to properly tune antennas using online calculators.

Near the end of the video he shows our multipurpose dipole antenna kit and shows how to adjust the telescopic elements for best reception. He demonstrates that simply extending the elements to the maximum length does not result in the best tuning, rather you need to tune the element length for the frequency being received to get the best results.

2020 SDR Guide Ep 4 : Antenna Basics for SDR Beginners inc RTL-SDR / Nooelec NESDR SMArt bundle

Characterizing Yagi Antenna Directionality via ADS-B Reception

Over on his blog Alex Krotz has been investigating whether adding more passive director elements actually affects the directionality of his home made Yagi-Uda antenna. Instead of using modelling software, Alex wanted a more accurate result that took into account all the imperfections of his antenna.

His idea was to receive ADS-B signals with his Yagi and a dipole antenna, then compare the data received in order to determine in which directions the Yagi receives better than the dipole. To do this he first creates a standard 2D map of plane tracks collected over a 24hr period for both the dipole and Yagi. A gaussian blur is applied to the two maps in order to fill in blank space and the data is normalized. Then he simply subtracts the dipole plot from the Yagi-Uda plot. The resulting difference plot reveals a mapping of where the Yagi receives better or worse compared to the dipole in a 2D plane.

Directivity of the Yagi revealed by comparing against a dipole
Directivity of the Yagi revealed by comparing against a dipole

Testing an SDRplay RSPduo with Bonito Active Loop Antennas

Bonito is a company that sells various active dipole and loop antennas for ham radio and DX applications. Recently they decided to test their MegaLoop FX and MegaDipol MD3000DX antennas on an SDRplay RSPduo, and compare it against a higher end WinRadio. Bonito found that the RSPduo performed well on the weaker longwave stations, but the Winradio outperformed it on the stronger ones. The differences were due to the better dynamic range of the Winradio.

The article goes on to make some recommendations for using their antennas on the RSPduo. They write that if intermodulation due to very strong signals occurs, there are some fixes that can be applied on their antennas to desensitize them and prevent overload. With the loop, a smaller loop size should be used, and the gain selector should be set to medium or min. With the dipole, they note that shortening the elements, and using it in an L-configuration with the lower radiator pointing towards the interfering signals can be used to attenuate them out. This works because a dipole configured in a L shape provides a bit of directionality.

The article also notes how grounding, very good coax shielding, good quality USB cables and galvanic isolation are all very important for reducing noise.

Bonito RSPduo Antenna Test Setup
Bonito RSPduo Antenna Test Setup

Tom’s Radio Room Tests and Reviews the RTL-SDR Blog Multipurpose Dipole Kit

Over on his YouTube channel Tom Stiles (hamrad88) has been experimenting with and reviewing our multipurpose dipole kit. Tom is a ham radio YouTuber who runs a show that produces content often, so we encourage you to subcribe to his channel if you're interested. Tom reviewed our dipole kit over a series of 5 videos which we link here [1: Discussing the product], [2: Unboxing], [3: First ADS-B Tests], [4: Second ADS-B Tests], [5: Third ADS-B Tests]. We post have embedded video 2 and 5 below.

In his testing Tom finds that using the antenna in the vertical orientation improves ADS-B performance. This is expected as ADS-B signals are vertically polarized, and so the antenna should be too. By using the included suction cup mount Tom is able to get the antenna attached to his window which improves reception by getting the antenna as close to the outdoors as possible. This is an expected use case for the antenna, and it's good to see that good results are being had!

If you're interested in the set please see our store at www.rtl-sdr.com/store, or use the links provided in Tom's videos. We also have a tutorial and use case demonstrations for our dipole kit available at www.rtl-sdr.com/DIPOLE.

TRRS #1384 - RTL-SDR.COM Portable Antenna - Parts

TRRS #1388 - RTL-SDR.COM Antenna Testing Pt 3

Akos Tests the RTL-SDR Blog Multipurpose Dipole Kit

Over on his blog 'Radio For Everyone' Akos has been testing out our multipurpose dipole kit for ADS-B reception. He goes over each of the components in the kit and does some tests with the kit set up outside. His results show that the dipole kit when used with the smaller antennas can compete favorably with the more expensive FlightAware antenna. We note that the dipole antenna is not designed to be used outdoors for extended periods of time as Akos did as they are not weather proofed for rain. The antennas are designed to be used temporarily outside in good weather conditions. Waterproofing could potentially be achieved by oiling the metal, or potting with hot glue etc.

Akos also does a comparison of the dipole used in two configurations. In one configuration the antenna is used in the recommended vertical orientation, and in the other position in a bunny ears configuration. Antenna theory says that the vertical orientation will work best as ADS-B signals are vertically polarized, and the results confirm that that is true.

FlightAware Antenna vs Dipole
Akos' Results: FlightAware Antenna vs Dipole