I've been trying to recive NOAA automatic picture transmission (APT) pictures for a year now.

I never got a picture with V-dipole, so I decided to build a double cross antenna. I used 75 ohm coax because here in Italy I can't find 50 ohm cable. I used galvanized gardening wire for making the dipoles. Why is there no signal? (Sometimes I see it but SNR is only 5 or 10 db.)

If this can help I live in south Italy, in a city named Messina. I have a DVB-T USB stick (RTK820T2.) I built the antenna with wood. I even tried to use a fridge door as reflector. Nothing. I tried all possible settings and softwares. Still nothing. My antenna is at 2 meters up from the ground. I would really like to hear your possible solutions.

  • \$\begingroup\$ Can you link to the plans for the antenna? \$\endgroup\$
    – JRE
    May 8 '20 at 9:55
  • \$\begingroup\$ Yes!They are in this instructable:instructables.com/id/… \$\endgroup\$ May 8 '20 at 10:03
  • \$\begingroup\$ I don't know about your antenna, but it seems the double cross antenna uses lengths of coax to join the signals from different antenna elements. The lengths are related to the wavelengthof the radio signal in the cable. If you used 75 ohm cable instead of 50 ohm cable, then the lengths will be wrong. They could be recalculated, or you could just order proper 50 ohm cable from a European supplier. TV equipment is 75 ohm, and available in hardware stores. 50 ohm cable usually has to be bought from places that specialize in radio communications. \$\endgroup\$
    – JRE
    May 8 '20 at 10:04
  • 1
    \$\begingroup\$ Your "instructable" has the same diagrams as the PDF I linked to. I'd work from the PDF rather than the instructable. \$\endgroup\$
    – JRE
    May 8 '20 at 10:07
  • 1
    \$\begingroup\$ In any case, when you build something you don't understand it is better to follow the instructions exactly. You don't know enough to know what you can change and it still work right. Don't change anything. Build it as described. You can experiment another time. Get a working one first, then you can make changes to another one and see what happens. \$\endgroup\$
    – JRE
    May 8 '20 at 10:25

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