Jim, 43' was chosen as a length because it represents 5/8 wave on 20m, which is the point at which a higher angle lobe starts emerging, but groundwave is maximized. Clearly, the antenna is the bigges
Even a low Yagi (25' on 10 meters) has a take off angle around 15 degrees. The 43' vertical is much too tall to be usable on 15 and particularly 10 meters. On 10 meters the dominant lobe is at 57 de
Seems to me the 43-foot verticals are reasonably good for operation between 40M-20M where the lobes are contained to low angles and where the antenna can achieve good radiation efficiency without to
". So, then, what about this trade-space (again, in the world of fairly inconspicuous antennas).. You could have a ground mounted vertical (of whatever length) OR a shorter vertical sticking up from
In my opinion, the "optimum" solution consists of two antennas. The first would be a roof mounted 22 foot vertical (either a "half size" 43' vertical with tuner or an R5/AV-620) for 20-10 meters and
When you start talking about 12 foot high vertical dipoles, you really need to revisit your assumption of a lossless matching network. With big, fantastic loading coils at the center with Q=500 , a
<snip> And, also Joe's comments about multiple antennas. So.. given one fixed length element, the trade is to make it long enough that the efficiency isn't wretched on the lowest band of operation, b
Where did that 12 - 15 ft above a structure come from? - m --Original Message-- From: towertalk-bounces@contesting.com [mailto:towertalk-bounces@contesting.com] On Behalf Of jimlux Sent: Tuesday, Jun
From a Rohn pamphlet called "Manufacturer's Technical Information for Bracketed or Self Supporting Towers." I don't recall if the information is in a Rohn catalog or online. Cheers, Steve K7LXC TOWE
I'm not sure, but you see restrictions of "12 feet above the highest point of the structure" for all sorts of things, so I suspect the FCC just adopted it for the old CB antenna rules. I just looked
Correction... the FCC specifically rejected a particular limit.. They had received comments prior to the rulemaking recommending the BOCA building code which says that permits are not required for st
Actually the very old rules for Citizens Band did have a "20 feet above the structure" limit. If I recall correctly - this comes from 40 years ago - the rule applied to the highest point of the ante
Thanks.. I knew it was something like that.. so the 12-15 ft is probably a building code kind of thing (and who knows where it comes from..probably because lumber or pipe came in 10 foot lengths or s