new vertical dipole antenna experiment
It pays to revisit supposedly old documentation. Stuff that we have once read and sometimes consciously think that we may never need again in this lifetime. Fortunately for us, our subconscious does not subscribe to that line of
thinking, and like the good computer it is, even though we may not appreciate it, continues to update and compile data on our behalf. When the time is right we get a flash of inspiration, a burst of knowledge, or whatever we want to call it, because all the pieces just fall neatly into place. It is not by accident, but many of us don't know that and maybe even more don't really care.
I just had that experience a few moments ago, and my next vertical antenna experiment is shaping up. Some time ago I viewed this website and did not give it a second thought because I could not handle the center feed point for the antenna, nor the 70-foot vertical section. Today, some months later, I am on the web page again, the data is still the same, but I now see it from a different perspective, and I believe that I have found the answer to a question posed by many hams in the forum. It is also a solution that I very truly welcome.
This is the answer to working the vertical dipole on two bands with one feed line. In my case that will be 40 and 80 meters. For my operating frequencies the antenna is re sized to half the given dimensions, and the feed point dropped from the center of the vertical section to the bottom. This layout will now look just like one half section of the conventional top and bottom loaded vertical dipole antenna. According to the theory the other half section is necessary to maintain symmetry and cancel the horizontal radiation component, but if we need to have contacts closer home, we may fore go that section, to get the high angle radiation.
My antennas sits above my chain link fence, below the 10-foot level, but it works for me. I do not use a scrabble wound balun, but a properly wound solenoid balun on 4.5-inch PVC. It is the real deal. More on the solenoid balun can be found here. If you are new to this vertical dipoles antenna stuff take a look at this web page and if you get serious and think that you can handle it give it a shot. You may also wish to contact hams who may be as crazy as I am about vertical antennas here.
I don't have any antenna modelling software as yet but that will not delay my antenna experiments. The SWR bridge and my pocket calculator are all that I really need to cut and prune this antenna to resonance. It is absolutely essential to use a proper balun in front of the SWR bridge or you may have to pull out what is left of your hair. I subscribe to feed lines that are half wave multiples at the operating frequency. The suggested arbitrary coax cable lengths just do not work for me.
I believe that every ham radio station and antenna installation is unique. In his Low Band DX Handbook, ON4UN shows how to set up the antenna from scratch, with measurements and calculations, and I find he is correct. If you don't have the tools you could get lucky and get away with arbitrary and guesstimated figures, but if you want to account for every milliwatt of RF you can seek to do it right. At the end of the day, what you put in is what you get out.
I am looking forward to this next experiment and I can't wait to hear what my ham neighbours will say. I have a plan toeep their s-meter on the stop, but they don't know it yet. I wish to have some feed back for you within the next week or two, so I will send Murphy on vacation.
thinking, and like the good computer it is, even though we may not appreciate it, continues to update and compile data on our behalf. When the time is right we get a flash of inspiration, a burst of knowledge, or whatever we want to call it, because all the pieces just fall neatly into place. It is not by accident, but many of us don't know that and maybe even more don't really care.
I just had that experience a few moments ago, and my next vertical antenna experiment is shaping up. Some time ago I viewed this website and did not give it a second thought because I could not handle the center feed point for the antenna, nor the 70-foot vertical section. Today, some months later, I am on the web page again, the data is still the same, but I now see it from a different perspective, and I believe that I have found the answer to a question posed by many hams in the forum. It is also a solution that I very truly welcome.
This is the answer to working the vertical dipole on two bands with one feed line. In my case that will be 40 and 80 meters. For my operating frequencies the antenna is re sized to half the given dimensions, and the feed point dropped from the center of the vertical section to the bottom. This layout will now look just like one half section of the conventional top and bottom loaded vertical dipole antenna. According to the theory the other half section is necessary to maintain symmetry and cancel the horizontal radiation component, but if we need to have contacts closer home, we may fore go that section, to get the high angle radiation.
My antennas sits above my chain link fence, below the 10-foot level, but it works for me. I do not use a scrabble wound balun, but a properly wound solenoid balun on 4.5-inch PVC. It is the real deal. More on the solenoid balun can be found here. If you are new to this vertical dipoles antenna stuff take a look at this web page and if you get serious and think that you can handle it give it a shot. You may also wish to contact hams who may be as crazy as I am about vertical antennas here.
I don't have any antenna modelling software as yet but that will not delay my antenna experiments. The SWR bridge and my pocket calculator are all that I really need to cut and prune this antenna to resonance. It is absolutely essential to use a proper balun in front of the SWR bridge or you may have to pull out what is left of your hair. I subscribe to feed lines that are half wave multiples at the operating frequency. The suggested arbitrary coax cable lengths just do not work for me.
I believe that every ham radio station and antenna installation is unique. In his Low Band DX Handbook, ON4UN shows how to set up the antenna from scratch, with measurements and calculations, and I find he is correct. If you don't have the tools you could get lucky and get away with arbitrary and guesstimated figures, but if you want to account for every milliwatt of RF you can seek to do it right. At the end of the day, what you put in is what you get out.
I am looking forward to this next experiment and I can't wait to hear what my ham neighbours will say. I have a plan toeep their s-meter on the stop, but they don't know it yet. I wish to have some feed back for you within the next week or two, so I will send Murphy on vacation.
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