A yagi can be made with a direct dipole feed, which is very simple.

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Please explain how. All the yagis I've heard of have a very low
feedpoint impedance. How do you use 50 ohm coax without a matching
device of some kind?

See for example

http://www.cebik.com/a10/ant35.html
http://www.naic.edu/~angel/kp4ao/ham/owa.html

just depends on how you tune the yagi. Give up a little (0.5 dB?) gain,
and the impedance can be 50 ohms.

Torsten
N4OGW