I Hate Antennas

I'm trying to cancel cable TV because I can't afford it anymore (nor any other alternatives) so I'm going to antenna TV again.

This is a cross post from a forum that these TV stations watch, so hopefully I can get help there too, but perhaps help here also:

I can pickup WFTV very great, nearly 95%. WESH, not so much. It depends on how the antennas are configured. I explain below.

So I have two antennas, a regular VHF antenna, with a clip on bowtie antenna. I use a VHF/UHF 300 ohm combiner to single 75 ohms adapter, so I can use them on my converter box. With WESH, if I detach the bowtie from the combiner, it gets a good 85%. However, if I attach the bowtie I get a low 20%-48%. I know WESH is VHF, but I'm confused why all of a sudden the bowtie is affecting the VHF antenna. For WFTV, I need to have the bowtie attached or the strength is very low.

Ok, so maybe I need a switch to activate one antenna at a time, I can deal with this, but WRDQ, this is a mess.

I can't get WRDQ no matter what I do. VHF only antenna, 0% - expected as it's a UHF station. UHF antenna is a mere 20% if lucky, but usually keeps going back down to 0%. It will sometimes go from 0 to 40, then back down to 0, like a rolling reception or something, and I can do nothing but just sit there and watch.

I can't afford an amplifier, and can't afford a new antenna. Is there anything I can do to improve the reception I'm getting here?

What cable are you using for the UHF antenna downlead?

The built in twinleads on the uhf antenna.

Interaction of antennas all depends on their impedances and what exactly the combiner is doing.

Example: if your UHF antenna receives some station just fine, signal goes down the cable, reaches the combiner, and if the combiner is just a -3dB wideband splitter, then half the UHF channel's power goes down the other two cables, half to the VHF antenna and half to the TV set. Presumably, the VHF antenna sucks at UHF, so it reflects the incident power, back towards the combiner. The reflected power was half the UHF's received power; half now goes back into the UHF antenna, and half goes to the TV set. But with a phase shift due to the length of the VHF antenna's cable plus whatever phase shift it adds. The energy reflected back to the UHF antenna (which is 1/4 what it received) reduces its efficiency, while the 1/4 sent to the TV will interfere with the straight path 1/2, so that depending on phase shift, the TV sees 1/4 to 3/4 of the actual received power overall, but never the 100% it would receive if the UHF antenna were directly connected. This effect is strongly cable and antenna and frequency dependent, so a weak channel might be adjacent to a strong channel.

Now, if the combiner is an RF diplexer, then it has a filter which keeps low frequencies on the VHF side, and high frequencies on the UHF side. If this is the case, then the antennas need only be matched to the line, to the diplexer, to the TV, and reception will depend only on the antennas themselves.

In any case, the antennas themselves are always a concern. A simple antenna is resonant, meaning it works for a couple channels, and that's about it. Even a regular dipole isn't actually too bad on bandwidth, but not TV UHF good. If you know exactly what frequencies you want to receive, and where they are, you can fairly easily cut an antenna and point it in the right direction -- nice thing about UHF, antennas are small and don't take much material.

Tim

Here's a video I made yesterday showcasing the setup I use and the channel reception. You'll see when I get to channel 27 I don't get squat.

http://www.youtube.com/watch?v=eGWcWusl-L4

I'll take apart the combiner to see what it contains.

It's just funny that I literally can't get channel 27 nearly at all. Sometimes I can get one frame of video, but then that's it.

We use a closed loop antenna (approx 18" diameter, 1/4" copper tubing) that I originally made for analog broadcast. It's connected to coaxial cable (with an old-style adapter that connected cable to TV antenna screws). A stiff copper wire loop (12-16 gauge?) should work just as well.

The cable is a custom "Y" that runs to two devices, but I don't remember whether I used resistance to equalize the signal or not. If so, it wasn't much (maybe 10R?).

And it's all indoors. The top of the loop is around 7ft off the floor, but we're on fairly high ground here. We get the two nearest stations (3 digital channels each), one is less than 10 miles away, the other is probably 25-30. Signals run around 70% for the near one and 30-40% for the other one. However, moving it around in the same room can change things drastically.

Also, a set of rabbit ears can surprise ya, especially if set/hung high as possible.

Not sure if that helps, but it might give ya some low budget ideas.

These are supposed to be good.
http://cosinekitty.com/hdtv/

never tried one because as luck would have it, a $20 outdoor amplified model mounted on the roof of a 1-1/2 story house was more than enough to get all 7 stations in our area.

I was planning on making 3 of the antennas I linked you, and mounting them in a triangular fashion, mounting them on top of my mast and using relays to select the antenna of choice for changes in direction. Was gonna try that with my scanner.


That above antenna is a very basic form of fractal antenna. Basically only the first iteration of the fractal. they can be elaborated on as such.
http://www.instructables.com/id/How-to-mak...HDTV-DTV-plus-/


And this is the theory behind why fractal antennas are good at what they do.
http://en.wikipedia.org/wiki/Fractal_antenna
As you can see in the article, they can get very complicated in design, however even in the basic
forms, they operate on the same principal. The more levels or iterations to the fractal, the more effective the antenna is at operating at a wider range of frequencies.

The fractals have a bit of gain on their own, and are somewhat directional, putting a reflector behind them increases the gain but makes them quite directional. So if you have 1 weak station you want to receive, the fractal pointed at it should be no issue. If there are more than one weak signal, a way to rotate the antenna is necessary, or have switchable antennas (such as the triangular antenna I want to make).

Have you tried your UHF antenna on VHF signals? All the UHF antennas I have used have had no problem with VHF. Are the antennas you have passive or active?

Sorry didn't see the video, have no access to sound at the moment.

Hrmmmm...

*rubs chin*

Skeith, you might be on to something.... a fractal, steerable array!

"I'll take apart the combiner to see what it contains."

if you paid 10 bucks for it , don't bother ...
it is not a directional combiner .

I got a 'Leaf' digital hdtv antenna based on Amazon's ratings and popularity. It works pretty dang well. Many channels are full 1080 HD and are coming in crystal clear on the LCD tv.

Just out of curiosity, y'ever figure this out.