8/13/08

The Double Bowtie

When I decided to simulate this antenna, all I had was this photo of it. So I assumed it was 16 inches wide, like the 4221, and I scaled all of its dimensions accordingly. The simulation results were fantastic. It blew away every other indoor antenna. It even rivaled some outdoor antennas.

Unfortunately the real antenna is only 12.5 inches wide. It is great above channel 40. But it is just too small for the lower channels.

If you are using one of these for channels below 30 and getting marginal results, wrap some aluminum foil around the four elements ends to extend them by about an inch. I think you will see a nice improvement. (Two inches would be even better, but will hurt the higher channels.)

The double-bow is made in China and has been sold by Channel Master as the CM-4149. It used to be carried in Radio Shack stores as the 15-623.

The double-bow comes with 300W twin-lead ribbon cable. For UHF, ribbon cable must be kept one inch from anything metal and not touching any substantial thing that is plastic. Otherwise a portion of the signal gets reflected and retransmitted. Ribbon cable is OK if you can set the antenna on the back edge of the TV and dangle the wire so that it doesn’t touch anything. But for most people this is not convenient. Many people who buy this antenna replace the wire with a balun and some 75 ohm coax. You will need soldering equipment to do that. Eventually the elements will end up slightly bent, the result of the antenna constantly getting knocked over.

There are 16” versions of this antenna: The DB-2 by antennasdirect.com and the 4220 by Channel Master. They are the best indoor UHF antennas available. If you are considering a double-bow, you should probably buy the DB-2 or 4220 instead. However the DB-2 and 4220 are outdoor antennas (small enough for indoor use) and lack a stand. If you buy one for indoor use, you will have to invent a stand that will hold it up.

This page is part of “An HDTV Primer”, which starts at www.hdtvprimer.com