On Mon, 11 Feb 2013 14:15:33 +0000, Channel Jumper
wrote:
If you are building a repeater - you use a Station Master - commercial
grade antenna, not a cheap vertical like the Diamond X 50.
http://www.wadsworthsales.com/Pages/celwave.aspx
Thanks for the sage advice. There were problems with the installation
which prevented the use of heavy antennas with a high wind load. We
were offered a free 20 year old super station monster antenna but
turned it down due to the size (22ft). The Diamond F22a on the VHF
repeater has been quite adequate. While I'm sure the station monster
antenna would work well for those in the distance, we are more
interested in local communications. VHF and UHF coverage:
http://802.11junk.com/jeffl/coverage/k6bj/146mhz/k6bj-146-3d.jpg
http://802.11junk.com/jeffl/coverage/k6bj/440mhz/k6bj-440-3d.jpg
If you look at the photo of the (former) antenna tower[1],
http://www.LearnByDestroying.com/k6bj/K6BJ%20Repeater/slides/Antennas.html
you'll notice that the Diamond X50 was located so that it would not be
inside the antenna pattern of the upper Diamond F22a. The VHF antenna
was also limited in height by the proximity of the county and Verizon
radio vault and tower. This arrangement limited the length of the UHF
antenna to approximately that of an X50. I could have used a longer
UHF antenna, but I wanted altitude to clear some obstructions, rather
than gain. Since the UHF antenna was side mounted, the grounded arm
under the antenna tends to create some uptilt in the antenna pattern.
With a fairly low gain antenna, such as the X50, the effect is
minimal. Were it a higher gain antenna, which would have a narrower
beamwidth, the effect would be sufficient to dramatically reduce
signal strengths below the horizon. I've had to deal with this on
mountain tops quite often, and have sometimes resorted to mounting the
antenna upside-down in order to take advantage of the effect.
For the curious, the black yagi is the 420MHz link to KI6EH. The
coaxial antenna is a spare antenna for plugging in test equipment and
HT's when working on the machines.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558