antennas again – make-shift DVB-T antenna

We were chilling in countryside property over weekend and EuroCup 2012 was on. Good. No, in fact bad, because we had TV set, we had STB from local DVB-T provider, but no antenna. Quick check on frequencies our DVB-T is available on, revealed that channel we were after is is either on 474MHz or 530MHz depending on what tower we can get signal from. My assumption was that 474MHz tower is closer (later I was proven wrong), so I went looking for materials to make an antenna, I opted for so called folded dipole as it is extremely simple to build and has somewhat broader bandwidth than regular dipole. Search for materials on-site gave me following – piece of ~2.5mm insulated copper wire, piece of 75Ohm coax cable, piece of scrap cardboard and antenna connector, everything I needed!
Next, went to El Goog, searched for folded dipole calculator and found out that length of antenna in  meters can be calculated by formula 145/freq in MHz, so that was ~30cm. Off I went, copper wire got bent to shape, cardboard used as holder for it all, coax connected to antenna by wire wrapping and connector attached to the other end of coax.
While sipping our drinks we watched Greece win Russia 1:0 and we got signal from tower 73km away on 530MHz that this antenna was not designed for, if one can speak about any design at all in this case 🙂
make-shift DVB-T antenna

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