Question: Impedance matching

Moppusan

DTVUSA Rookie
#1
Hello all. Just getting into the crazy world of antennas, but I do know some electronics basics.

I recently looked into making my own antenna for OTA TV and came across a comment about just stripping 8 inches from a coax cable and hooking that up to my TV (Vizio 47" some-model, has built-in digital decoder). I thought "yeah, right" but went ahead and tried it anyway. Put the exposed copper in the window, connected it to the TV, scanned for channels. 2..3..6..15+ channels. At first, to me, it was devil voodoo magic, but I guess I just made my first antenna. My wife and I dropped TV from Comcast (not really saving a ton of money and only getting about 1/4 the internet speed...but that rant is for another day).

Long story longer...I decided to make this fractal antenna. The directions say I need an impedance matching transformer since all antennas are 300 ohms and TV inputs are 75 ohms. Being that I have some bare coax running straight into my TV this puzzled me slightly. Am I hitting my TV with a 300 ohm signal or is there something else going on here?

My main question would really be: do I definitely need the 300 > 75 transformer to use the fractal antenna? Or can I just attach the bare copper I have in the window now to the antenna I made and either blow up my TV, have a lot of noise in the signal, or something else fairly benign?

Some quick background on me: I play guitar (electric) and I know how important impedance matching is in audio signals, so I'm not trying to get out of buying a transformer (especially considering how cheap they are) I'm just genuinely curious about the technical side of the electrical side of antennas, and I want to be safe before hooking up something I should/shouldn't be hooking up.

Sorry for the encyclopedia. Thanks for any help, everyone.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#2
:welcome: Mopussan

If you search this Forum (or Google) you will find a better home-brew fractal antenna called Grabbit Ears. The designer of Grabbit Ears is a DTVUSA Forum Member and his similar design uses a balun and they are under five bucks.

Jim
 
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