Most over the air television antennas (indoor) that you would buy at stores are usually full of gimmickry. They tend to say that they are the smallest and have the highest gain and usually include a pre amplifier of some kind. In my experience pre amplifiers usually cause more issues than they help. All of these antennas are compromise antennas, and usually none are very effective.
Some of them are just flat plastic boxes with a small coax cable that plugs into your television. Others have a telescoping antenna element, just one which would be a monopole that has no counter poise. All very poor.
Granted there will be no one simple antenna that will efficiently cover the broad range of frequencies that encompass the over the air television spectrum. Log periodic yagi type antennas are the exception but of course more complex. What is shown here is also a compromise antenna in that it is not tuned for any particular frequency. Nevertheless, it is very simple and fairly effective in an urban environment where television broadcast signals are fairly strong. If you don't live near broad cast stations this is not for you, you need height and gain.
I stumbled upon this idea, it is not my own. Simply, you take a metal coat hanger cut the hook off, shape it a bit so that the distance between the top and lower half are even. You then take a 300 ohm to 75 ohm transformer available at most local stores that carry television antennas or television accessories. The 300 ohm twin lead end gets connected to the cut portion of the antenna coat hanger. This assembly gets mounted to an insulator of some kind in my case I used a piece of scrap wood which also allows me to stand it up and let it lean against a wall near the television with the element horizontal. That makes for the complete antenna, very simple. All you have to do now is connect it to your TV with some 75 ohm coax.
This antenna is called a folded dipole which typically has a feed point impedance of around 300 ohms at its resonant frequency. At other frequencies this will vary but that impedance transformer helps to mitigate the possible impedance swings vs frequency at the antenna by its ratio of 4:1.
Brief practical non-scientific testing has shown this to be a fairly decent performer all local stations come in with around middle level signal strength as shown on the television used for testing. The television under test is located in a low area of the city. Signal strength typically in this area is usually poor with indoor antennas.
This antenna is bi-directional in that you use it like a normal dipole and have it pointed in the direction of the station. In this case most broadcast stations are located in about the same direction. This antenna can also be expanded on later by adding a reflector this will create a nice gain directional antenna.
Image below, have fun!
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