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Contact information: Charlie,
AD7MD Linda,
NI7Y CCDAntennas
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ATTENTION!! New 40/80 meter dual band version now replaces the 80 meter single bander!! And BOY, does it work well!!! And, for our 80 meter antenna customers, we have info to easily modify your current antenna to cover 40 too!
The big question is, what is it and why would I want to have one? I've found that of the published authors on the subject of CCD antennas that there is some amount of disagreement on how it works. Well, not disagreement as much as different ideas on how and why it works. But, they all feel there are enough advantages to try it. If you are interested in the latest study of the CCD by the first designer of actual dual band versions, check out AD7MD's web site. The CCD is a full wave dipole (or long wire) that has a series of capacitors mounted along the wire. The idea being that the current distribution along the entire antenna wire is controlled. Hence, Controlled Current Distribution! Some references talk about constant current situation so that name is misleading. It's not that the current is constant like many have thought in the past, and in some of the articles you'll see below. In fact, we are controlling the current. In any case, there are still plenty of reasons to look into one of these babies!
What we have here is the ability to have a longer wire than the standard half wave actually resonate and match, even on two bands at a time, without the use of a tuner. The more resonant wire in the air, the better you'll receive and transmit. That's always a fact. A full wave antenna would usually have about 4K ohms at the feed point. Pretty hard to match a 50 ohm or even 300-600 ohm load to that. With the addition of the capacitors we can have a full wave antenna and have the feed point load around 200-500 ohms, or, something we can work with. Add either ladder line or a 4 to 1 balun and you have your match. Another big question then is, "Why don't I see more of them?" They were first introduced in 1978! Until now no one had come up with an easy way to build them commercially, build them to spec so each works exactly the same, and build them so they would be relatively maintenance free. What we've come up with is an easy way for people to build their own or order one that is assembled. Pros:
Cons:
There is no magic antenna that just does it all. If there was, we'd all be using it. A three element yagi at 75 feet will certainly work better than a CCD at 10 feet, or even 75 feet for that matter. But, there are plenty of advantages to the CCD and depending on your needs it might be worth a try.
I found mine to be fairly quiet, yet the signals were still nice and strong. I also used it under the eves of my house and found it was resonant on the same frequencies as it was when it was in open air. Because wood is not a good insulator it still raised the SWR some. It might go from 1.5:1 in open air to 4:1 under the eaves. But, the reception and transmission comes close to what you would find in open air even with it under the eaves. So, it might be a good antenna for those who live in HOA controlled communities. Remember, these antennas can be bent around corners with little or no change in its operation. Oh, and metal gutters or flashing around the eaves does cause problems so be wary of that if you have them. If you have additional questions please feel free to contact us. The info is on the left panel. |
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