# Bow Tie antennas impedance

I see on the internet that a radio amateur made bowtie antennas for transmitting and receiving on the 2 meter and 10 meter bands. They produced very good SWR bandwidth when fed with 50-$$\Omega$$ coax. Why, then, are bow tie antennas for UHF TV connected to 75-$$\Omega$$ coax through a 300-$$\Omega$$:75-$$\Omega$$ stepdown balun?

Commercial 4-bay bow tie antennas connect the feedpoints of the bowties with ~14ga solid conductors and feed the antenna through a 300-$$\Omega$$:75-$$\Omega$$ stepdown balun. If the impedance of a single bow tie is close to 50-$$\Omega$$ or 75-$$\Omega$$, then connecting four of them with half wave wires should result in an impedance around 12.5-$$\Omega$$ or 18.75-$$\Omega$$, which is a very poor match to the 300-$$\Omega$$ input impedance of the balun. This situation would be even worse for an 8-bay antenna. How do these antennas work?

• Please tell us where you found the amateur and commercial antennas so we can address your specific questions. – Brian K1LI Mar 25 '19 at 12:36
• Hello Robert and welcome to the site! I believe that I know the answer, but I would first like to see what these look like. Please provide either photos or links so that we can help you. – Mike Waters Mar 25 '19 at 14:31
• I looked at a couple of commercial UHF TV 4-bay bowtie antennas. Are you sure the feedline is connected to a transformer? It looks like it might be a splitter/combiner. – Brian K1LI Mar 25 '19 at 20:00