Paul Finch wrote: > Hello, > > Has anyone run into any of the RFI/Bird Technologies 8 loop folded > dipole antennas, they are very similar to the DB-304 except this thing > is huge! The dipoles look to be at least 1/2 inch in diameter and are > mounted almost one foot away from the mast. A tower crew brought two of > them out here that they are going to mount on my tower for a customer. > Once again "M" bites me in the butt with their huge stuff they want to > install on/at my tower. > > The antenna is very broadband though, on the label it says 136 to 173 > MHz, I will test with the antenna analyzer and post it here. It says it > is 6 dB gain. You can find the information at > http://www.txrx.com/product/product_view.aspx?UID=963AB5AD-59DB-4B4C-B181-6805057E3051 > . > I would expect these antennas are pretty expensive, I bet not many Hams > can afford them much less have a tower that would support a beast like this. > > If anyone is interested I have pictures of them laying in my building I > can email privately. > > Paul > WB5IDM
Big broadbanded dipole arrays really are not that uncommon... the wider/bigger elements make for them to be VERY broadbanded, which is nice for combined systems, etc. Maybe for "ham grade" they are "big", but at commercial sites? Nah... you see 'em all the time. They last a hell of a lot longer than ham-grade antennas too. The "foot away from the mast" is 1/2 wave spacing to the mast, giving a better pattern if they're all on one side. If they're on both sides, that's kinda interesting. The link you sent shows the more common "DB-style" with arrays on both sides of the mast. 4 and 8-bay Sinclairs and others where all the dipole arrays are on one side, and not mounted across from one another, are just as big as what you're describing. Especially if you buy the "heavy duty" option for bad-weather sites. http://www.sinclairtechnologies.com/catalog/product.aspx?id=1702 There's one that's the wrong band (just hurrying to click to find you a photo), all beautiful 33.7 feet of it and 90 lbs. At one of our sites, TWO of these are used for a split TX/RX antenna system for a receive multicoupler and transmitter combined VHF system. (Well, not these, but two tuned for the ham bands.) Yep... 80 feet of linear antenna... and 180 lbs of dead weight. Not much separation between the two ... but wow does that system talk and hear... Nate WY0X
