One thing that is over looked when moding a multi-bay antenna such as the 4 bay folded dipole array is the interbay spacing. Depends on who made the antenna, but this should be either 1 free space wavelength or 1/2 of a wave. Changing the element sizes will improve SWR, but without changing the bay spacing you change the electrical beam tilt of the antenna (your "pancake"). This may be useful in valley or on a mountain, but generally not ok for plains. Also don't forget that the phasing harness needs to be resized too, you will need to know the velocity factor of the coax you are working with in order to do this.
Instead of all that, I can honestly recommend you try the Tram 1491. Avalible from Repeater-Builder.com through Zimmerman Electronics. http://www.repeater-builder.com/products/VHFantennas.html We put ours up on the 146.64 repeater over the weekend and the repeater works hella-good now. The "cutting chart" was a little lacking in information, only giving 2MHz increments, but some dead reconing and averaging was used to cut the antenna for 146.5. With pwr adjusted for 50W fwd we had approx 200mW reflected. The antenna has a price that can not be beat which will not break anyones budget. I was going to rebuild a station master clone but the cost of the RG-11, brass, epoxy, hot glue, torch to do so out weighed buying the Tram. Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
