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Title: FOLDED DIPOLE Post by: AE1CT on March 15, 2013, 03:44:28 PM I PRINTED OUT A PICTURE OF A FOLDED DIPOLE FOR 75 METERS FROM KB3AHE AND HE IS USING LADDER LINE. CAN I USE RG-8U COAX IN PLACE OF THE LADDER LINE AND IF I CAN WHAT TYPE OF BALUN DO I NEED TO USE (EI: 1:1, 4:1, 6:1) I KNOW THAT B&W MADE A FOLDED DIPOLE MADE FOR COAX. ANY IDEAS ON THIS WOULD HELP ME BE HEARD ON 75AM..
Title: Re: FOLDED DIPOLE Post by: W2VW on March 15, 2013, 07:24:16 PM tx coax balun balanced line antenna.
BalUn is balanced on one side and unbalanced on the other side just like a Jaw And Son 500 power supply. Title: Re: FOLDED DIPOLE Post by: Steve - K4HX on March 15, 2013, 08:39:18 PM In other words, no you cannot use coax with that antenna. At least not a single coax. If you made the thing about 76 feet long, you could feed it with two 50 Ohm coaxes in parallel (25 Ohms). The feed point Z would be around 20 Ohms. Or feed it with a quarter-wave section of the paralleled 50 Ohm coax and then a single 50 Ohm coax back to the transmitter. Unfortunately, the 2:1 SWR bandwidth would only be about 50-60 kHz, maybe less. That doesn't give you much room to roam and your stuck on one band. And it's likely you would have to tweak the length plus or minus to actually get the low SWR spot on the frequency you want to use, say 3880 kHz.
Title: Re: FOLDED DIPOLE Post by: W2VW on March 15, 2013, 08:53:21 PM tx coax balun balanced line antenna. BalUn is balanced on one side and unbalanced on the other side just like a Jaw And Son 500 power supply. Thanks Steve. I ran out of words. |