| + + + - D L 4 X A V - jo 43 xn - h a m b u r g , g e r m a n y , e u r o p e , e a r t h + + + |
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Guenter,DL9HCG made a lot of tests to develop a 2 band logperiodic antenna. the 2 frequency bands are separated 1:3, that means that the elements are about 0.5 lambda for VHF and 1.5 lambda for UHF. Guenter set the element spacing for 70cm and the element length for 2m. that results in high gain on both bands.
hereis the link to DL9HCG s homepageGerman language. and this is DL9HCGs " Duo-LPDA-04.pdf " 630kb. use google translator to translate a html version to your language. this is an older PDF in german and english. |
12 elements this is the first LPDA i made. boom : 15x15mm 85cm (1m) long. elements : 6x1mm tube. 2m gain : 10.2 dBd. 70cm gain : 12.5 dBd. the horizontal beamwide is narrow on 70cm. but vertical it has a wide beam. it was not easy to follow a LEO satellite by hand, with the antanna mounted on a tripod. |
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so i tried less elements, a quick and dirty made 4 element (6 dBd/70cm 7.75dBd) has a real wide beam. than i tried it with 7 elements. boom : 10x10mm 46cm (57cm) long. elements : 4mm solid 2m gain : 7.6 dBd 70cm gain : 10.2 dBd its a good choice for portable SAT operation. except the 4mm elements. 6mm tube elements are much more solid. |
| i had problems to mount the elements the DL9HCG way when i made the first LPDA, i had to fix the elements with screws at the boom, what is no smart design. i will make the next LPDA like shown here. |  |
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with the rest of another antenna project and some bicycle spokes
i made this 15 element LPDA for UHF and L-band satellite service |
366 - 566 MHz and 1098 - 1698 MHz |
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boom : 10x10mm 40cm (48cm) long. elements : 2mm V2A UHF gain : ~10 dBd L-Band gain : ~12 dBd |
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