Doug, It's not clear whether you want to connect an external antenna directly to your cellphone, or if you want to install a repeater system that will enable you to place and receive calls anywhere within your house, not wired to your phone. It also makes a difference if your cell provider operates a system in the 800 MHz band or in the 1800/1900 MHz band, or both.
I have installed and/or specified several repeater systems at my work, which has many buildings that are Butler-type, completely metal with very few perimeter windows. A six-element Yagi antenna is on the roof, pointing to one of several cell sites. A BDA (Bi-Directional Amplifier) is on the wall inside the building, and a simple dipole antenna is mounted upside-down on the dropped ceiling near the BDA. This works perfectly for the majority of workers in the building. The steel roof provides complete shielding between the two antennas, so there is no loopback between them. The occupants of offices near windows will have a problem when the direct signal through the window competes with the repeater signal. Perhaps your safest solution is to install a modest omnidirectional antenna on your roof, with a direct connection to your cellphone. Repeater systems should be designed and specified with care, so their use does not "jam" multiple cell sites with a powerful signal. A poorly-designed repeater system may degrade the service available to many other subscribers. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Davies, Doug A FOR:EX Sent: Thursday, April 19, 2007 11:06 AM To: Repeater-Builder Subject: [Repeater-Builder] OT: Cell Phone Yagi I know this is off topic, but I also know there is a wealth of knowledge here. I need to install an outside antenna to ensure continuous cell phone access from my home QTH. The commercial 7-element Yagi is over $100. I know I can make one cheaper than that out of 1/8" dia. aluminum tubing or welding rod. I just don't know what would be the best way to feed it. It would be great to use the feed system seen in Sinclair antennas i.e the folded dipole with the feed line going through the inside of the tubing but I don't know if coax that small is available in the odd impedence required to match the antenna properly to 50 ohm coax . There are other methods like the Delta match, Gamma match etc. but all of these require the feed point to be exposed to the weather. Has anyone tried to build one of these? Please share your experiences. Doug VE7DRF
