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WB4BYRBCD baLanced coiL dipoLe Antenna
with voLumetric optimization
FLASH!
Why I use a BCD [ ] Minimize electromagnetic energy fields radiated near the operator and gear. Mandated RF radiation calculations are only as good as you are at keeping the radiated energy off a nearby coaxial line and on the antenna. [ ] Quickly coarse-tune by adjusting length without cutting. Can be retuned in minutes [ ] Great for portable use, field day, or fixed installation where limited space or neighborhood restrictions apply. [ ] Can be tuned (or fine tuned) using most popular antenna tuners [ ] Can be quickly tuned to 1:1 SWR ratio with tuner [ ] Mounted indoors out of the elements, minimizes corrosion, detuning due to changing velocity factor [ ] Complies with neighborhood covenants against having pretty antennas. They don't even know they are there! [ ] $aved hundred$ of dollar$ on tower$, concrete pad$, versus typical half-wave installation$ [ ] May qualify for lower home insurance rates than conventional outdoor antenna installations [ ] Mounted multiple antennas parallel and within feet of each other (2:1 and 4:1 band ratios, not odd ratios) [ ] Mount 80 meter antenna in as little as 30 feet of horizontal space (less if tilted or Vee’d) [ ] Mount 40 meter antenna in as little as 15 feet of horizontal space. [ ] Mount 20 meter, 40 meter or even 80 meter BCD’s perpendicular to each other and switch for dual patterns, hence best reception. [ ] Low-mounted BCD’s have a near circular pattern, yielding good QSO’s in all directions. [ ] Regularly get 5&9 reports from Europe (broadside) on 20 meters. 5&9 +20 db off the end of the antenna for QSO a 1,000 miles away is not unheard of ... at 100 watts! [ ] Minimize lighting strikes – no sharp edges to act as lightning-attracting air terminals. Typical lower mounting height than conventional antennas also helps reduce the chances of a direct strike! [ ] Rated for up to 125 watts input to the antenna connector. [ ] Ready for PL-259 connector, no extra soldering [ ] Includes typical hardware required for indoor (attic) installation
[ ] All I needed to supply is the coax, antenna tuner and transceiver. And I’d need to supply that anyway. OK, you gotta install it, too. Typical installations take just a few minutes.
HANOVER TECHNICAL SALES, Inc.
PO Box 70 Battery Park, VA 23304 USA Now, you can build you own. Read on!
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 My apologies! We have ceased providing the BCD. It was just too much of a hassle for us, considering our day to day mission at Hanover Technical Sales. But for someone who wants one, they are not all that difficult to put together. The 20 meter BCD, my favorite, starts with a single standard Slinky, cut precisely in half, with the loose ends soldered to the first loop of the coil it abuts. The coils are soldered to an approximately $20 1:1 ratio balun from AES. The balun hangs from the ceiling. A messenger line (strong fishing line will work fine) is strung thru the coils, and thru the loop on the top of the balun, and landed on opposite "walls". That supports the coils so they pretty much traverse horizontally, stretched 7 to 9 feet out each way, clipped in place on the messenger line. I use an MFJ antenna analyzer to find the best length. I also use antenna tuners religiously, but less so now that I have started using the analyzer with each setup. You can Google slinky toys on the web. For a 40 meter antenna, you will need 2 Slinkys. For an 80, you will need 4 … and about linear feet to stretch them. I’ve considered trying a closed dipole, but haven’t had the time or space. I have not used ladder line. I coax to the balun. AND … I am a great believer in ferrite cores around the jacket of the coax as close to the balun as I can to reduce current flow on the shield as much as I can. I also put cores at various places along the coax so it is less likely to have an effect on transmission and reception … ie “divide” the coax into less than resonant lengths. Cores are cheap, and you can find them, probably even cheaper on eBay. I have also found that some of the double bazooka dipoles work pretty well (20 and 10 meters). I also use the antenna analyzer to trim those antennas to the resonant length … they always arrive cut long, thankfully. The double bazooka exhibits lower noise than does a Slinky dipole. I won’t bore you with the theory. 73 and hope to hear you and your Slinky on 20 meters one of these days! .
+++++++++++++++++++++++++++ "KNOWLEDGE IS POWER"Thomas Jefferson - 1817.
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