Instructions for Building a Portable Double Cross Antenna: Great for NOAA/Meteor Weather Satellites

Over on Reddit user merg_flerg has uploaded an imgur post that carefully details a step by step guide for building a double cross antenna. A double cross antenna is great for reception of satellites like NOAA and Meteor since it has a sky oriented radiation pattern with very few nulls. This means that it can receive satellite signals coming from the sky well. Alternative antennas for NOAA/Meteor include turnstiles and QFH antennas, although the double cross antenna seems to have the least nulls, meaning that the signal is less likely to fade in and out as the satellite moves across the sky.

merg_flerg’s design is also modified from the standard design slightly, allowing it to become easily disassembled and carried within a backpack. At the end of his tutorial he writes that he gets much better reception with his double cross antenna than he does with his QFH.

In the post he demonstrates the final constructed antenna decoding a NOAA APT weather satellite image with an RTL-SDR and the WXtoIMG software. See our tutorial for information on decoding NOAA weather satellite images.

The finished double cross antenna connected to a PC running an RTL-SDR and WXtoIMG.
The finished double cross antenna connected to a PC running an RTL-SDR and WXtoIMG.

15 comments

  1. Danilo Castillo

    I’ve done several tests with that antenna, here I leave my experience, the first time was a horrible performance I built with 50 ohm cable. there is a fact that little is named and that before building and that should verify is the number of ohms that the receiving device works, be it a LNA or SDR, handy, station base etc. in my case my SDR receiver is 75 ohms and I made the antenna with a 50 ohm cable, as the manual says they will realize that the SDR was practically hunting flies with horrible 90% signal losses, I thought between me, a woki toki toy is more senbile than this. my advice for those who build this antenna is to confirm how many ohms the receiving device works before starting to build, I changed the one of my cable antenna to 75 ohms and a little disillusioned by the first experience, I had already tried to change the connectors, cut a bit the cable move the positioning antenna and nothing was no improvement, I started the second test with that antenna, and a little disappointed by the results of the first experience, grab it and pull it on the roof without mast I already angry because it did not work, and the result of the second test with the cable of 75 omhs was spectacular, the losses were much reduced, I was able to capture the noaa18 without needing to raise the antenna to the mast, now that it works, I will paint it and I will add it to your mastil as it corresponds .. hopefully my experience will serve others, best regards 73 .. from Santiago
    From Chile

    • Raul Andres Moch

      Where did you find information about SDR regarding if it is 50 ohms or 75 ohms?!

      Mine is a cheap chinese DVB-T+FM+DAB receiver

      Best regards from Mexico

      • Johnathan

        You will need to look up the information on your particular equipment, Contacting the manufacturer would be my only suggestion. It seems that Daniel Had luck with 75 ohms and I had luck with 50. So there are definitely differences between the manufacturers of our respective pieces of equipment.

        I wish you luck!
        Johnathan

  2. Steve Ziegler

    Could this design be adapted for the 1676 MHz freq range to monitor weather balloons from the National Weather Service?

  3. Johnathan

    I built this antenna, it works like a champ. I used a little bit of a different method using 3d printed parts, but I used the same specs and I get great signal. I think what a lot of people are having problem with is that they aren’t using 50 ohm cable. Using 75 ohm Coax (TV Cable) Won’t give you a great signal.

  4. Don DeGregori

    It’s interesting to see 3 negative reports so soon! Maybe they have made mistakes in it’s construction or use?

  5. DE8MSH

    Hi merg_flerg!

    What does ‘better than old qfh’ mean? Has it a lower elevation performance? Or do you mean stronger signal power? Let us know :).

Post a comment

You may use the following HTML:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

This site uses Akismet to reduce spam. Learn how your comment data is processed.