Tagged: dipole

RTL-SDR V3 Amazon Back in Stock + A Preview of our Upcoming Multipurpose Antenna Set

The RTL-SDR Blog V3 is back in stock in Amazon USA (Dongle + Antenna) (Dongle Only). International buyers can continue to purchase units from our store at www.rtl-sdr.com/store.

Apologies for the long out of stock period, we sold out of our remaining Amazon US stock almost immediately a few weeks ago due to a large Reddit thread which popularized the Reddit /r/rtlsdr forums (a big welcome to any new RTL-SDR users!). Amazon is currently processing the new stock and it should be ready to ship out in a few days.

We also have a new antenna set in the works which should be ready for purchase in a few weeks. This antenna set is essentially a custom modified TV dipole with mounting kit. The kit will contain:

  • 1x Telescopic Dipole Antenna base with 20cm RG174 cable
  • 2x removable 22cm to 1M telescopic antennas
  • 2x removable 5cm to 13cm telescopic antennas
  • 1x 3M SMA RG174 extension cable
  • 1x suction cup window mount
  • 1x bendy tripod mount

Antenna Base

The telescopic antennas mount onto the antenna base via a screw, so they can easily be removed and interchanged between the large and small ones, or packed away for storage.

The dipole antenna base attaches to the suction cup or bendy tripod mounts using a 1/4″ camera screw. So any cheap camera mounting accessories like clamps, tripods etc can be used to mount the dipole as well.

The coax cable on the base also has a ferrite core choke on it to help decouple the feedline from the antenna, and there is a 100kOhm bleed resistor added to reduce static discharge.

Mounts

The included suction cup mount allows you to mount the dipole on a window (ideally outside) and orient it into a vertical, horizontal or V-Dipole position. The bendy tripod allows you to use the antenna on your desk, folded over a door, on a tree branch, pole, or anywhere that the tripod legs can be wrapped around.

Usage

The biggest problem that new RTL-SDR users face is the antenna. Most are starting off with a mag mount whip, and have no way to mount them outside where they should be for better reception. Keeping them inside can cause poor reception and increased pickup of local interference from electronics. Our dipole with the mounts aims to solve this problem.

Using a dipole generally results in better reception than with a mag mount whip, and also allows for easier outdoor mounting. The 3M coax extension cable allows you to get the antenna at least to a window in your room.

Note that although we recommend using the antenna outside, please remember to take the antenna back inside when not in use to avoid lightning/ESD/weathering problems. It is not designed for permanent outdoor mounting and please remember that any permanently mounted outdoor antenna should have good grounding to protect your radio against ESD and lightning.

For general use we recommend using the dipole in the vertical orientation as most signals are vertically polarized. The dipole can also be used in a V-Dipole configuration for excellent VHF satellite reception, such as for NOAA/Meteor weather satellites. Just extend the telescopic dipoles to be as close as possible to resonant at the frequency of interest using this calculator. Getting the length perfect is not critical, and actually using any length will still receive something.

Apart from NOAA we’ve also tested the dipole with L-band satellites. Together with an LNA and the smaller telescopic antennas it’s possible to receive Iridium and Inmarsat signals. Reception is not as good as a patch antenna, but you can still get the stronger AERO and Iridium signals quite easily. If you add a reflector made out of a small cookie tin the signals can be boosted further, and this is enough to receive the weaker STD-C and Outernet signals.

Eventually this dipole set will replace the mag mount antenna bundled with the dongles currently. Target price is between $9.95 – $14.95 for the antenna set by itself, and $25.95 for the dongle + antenna set. We expect the antenna set to be ready for shipping in 2-3 weeks, and about 3-4 weeks for the dongle + antenna set. More details and usage examples will be shown nearer to the release.

The Dipole Kit (Small antennas not shown)
The Dipole Kit (small antennas not shown)

Upgrading the Coax on a TV Dipole Antenna for Improved Reception

Over on his YouTube channel Corrosive has uploaded a useful video showing how to modify a standard TV dipole to make it better for general radio use. Many TV dipoles come standard with twin lead, or very poor quality coax cable. Corrosive shows in his video how simple it is to modify and improve one of these by adding high quality coax with a BNC connector.

These TV dipoles are great as general purpose antennas, and are especially useful for making V-dipole antennas for NOAA/Meteor M2 reception.

Using a TV Dipole Antenna for NOAA Satellite Reception

Over on YouTube icholakov has uploaded a video showing how effective a simple old TV bunny ears antenna can be at receiving NOAA satellite images. The old TV antenna is telescoping so it can be adjusted to be resonant for many frequencies, and for NOAA satellites about 20 inches makes it resonant. Using the antenna as a V-Dipole and placing it in a North to South direction optimizes the radiation pattern towards the sky, allowing for good reception of the NOAA satellite. Using it this way also helps to null out strong vertically polarized stations. More information on the V-Dipole can be found on our previous post where we posted about Adam 9A4QV’s idea to use the V-Dipole for satellite reception.

Also related to this post is a sneak preview on our new product: We’ve also caught onto the idea that TV antenna dipoles are extremely versatile, and are in the final stages of releasing a simple telescopic dipole product similar to the TV antenna used in this video. It will be released as an antenna set that comes with some portable mounting solutions like a suction cup and bendy tripod, and 3M of RG174 coax so that the antenna can be used anywhere. Target price is $10 -15 USD incl. shipping from China. This will probably also replace the stock telescopic whip antenna currently used in our dongle sets since the telescopic dipole is simply much more versatile.

ISS Packet Repeater Received with RTL-SDR

YouTube user ronpaulatemybaby has posted a video showing his reception of the International Space Station (ISS) amateur packet repeater on 145.825 MHz, using the rtl-sdr. He used a R820T dongle, two meter dipole, SDRSharp and decoding software MixW.

RTL-SDR Tutorial: Cheap ADS-B Aircraft RADAR

The RTL-SDR can be used as a super cheap real time air radar. Modern planes use something called an ADS-B (Automatic Dependent Surveillance-Broadcast) Mode-S transponder, which periodically broadcasts location and altitude information to air traffic controllers. The RTL-SDR can be used to listen to these ADS-B signals, which can then be used to create your very own home aircraft radar system. Compared to dedicated commercial ADS-B receivers which can go for between $200 – $1000, the $20 RTL-SDR is very attractive for the hobbyist in terms of price. However, note that the RTL-SDR probably shouldn’t be used for ADS-B navigation in a real aircraft for safety reasons. 

ADS-B broadcasts at a frequency of 1090 MHz. It has been discovered by the RTL-SDR community, that the RTL-SDR with R820T tuner has the best sensitivity at this frequency. The E4000 and other tuners perform poorly in comparison. So it is recommended that you obtain an R820T tuner if you want to set up ADS-B decoding with the RTL-SDR. Recently there has also been talk about the R820T2 tuner, which seems to have slightly better performance too. See the Buy RTL-SDR dongles page for more information on where to purchase.

We also now note that recently new higher end SDR’s like the $199 Airspy have developed very good ADS-B receivers that are several times more sensitive that the RTL-SDR.

Examples of RTL-SDR used as an ADS-B air radar

In this video, YouTube user Superphish shows a timelapse of air traffic over New Zealand using RTL-SDR, ADSB# and Virtual Radar Server.

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