Antenna Question

I have a TV aerial stuffed inside of my attic. It's wired to a two-screw connector on a plate in my living room. I've been using it as an FM antenna for my receiver for years now, and it's great.

Recently, I moved my television to the upstairs bedroom, since I almost never watch it. I don't have cable, so I've always had it connected to an amplified dipole/uhf antenna. Because of the layout of my townhouse - I am in the crook of an L-shaped section of brick buildings, the reception is terrible. So in the off-chance I want to watch a Lions game, it's mostly a bunch of digital garbage.

My question is, can I run a wire from my TV set into the attic and connect to the antenna itself where the wire running down into the wall also connects, without causing issues for either the TV or the receiver? Or would that cause some kind of circuiting issue?

I appreciate your input and patience; my understanding of the physics of electricity and antennae is quite limited. Thanks!

Yes you can.

You will need to use the correct type of signal splitter (75 Ohm or 300 Ohm) and there will be some signal loss incurred.

The only way you will know if you have enough signal is to give it a try.

Most of the over the air TV channels are in the UHF TV band and it may depend on the type of antenna that is in your attic and the direction that it is pointed.

With all signal reception it is location, location, location.

TV FOOL Station Locator may be of some help.

Depending on your location and signal strength a low noise RF preamp at the antenna may help over come the losses in the signal splitter.

With digital TV signals there is a definite threshold of reception and if the signal drops below that threshold, then receptions becomes problematic.

Thanks much!

After all these decades, starting last month with the Olympics, I completely gave up all my overpriced store bought antennas, and built three DIY types. The Grey-Hoverman, and a 1" and 3" star fractals. All using solid copper grounding wire. I could not believe the difference (betterment) and strength of the Grey and fractals.

For a townhome, apt, or anywhere, they are perfect for not only HD UHF tv reception, but for all my old analog receivers. Ive even now seen people hanging them in the car windows for HD radio.

Before you have to go running cable into the attic, build a few different styles of these and merely hang them directionally on your various walls or areas first. You might be surprised at how fantastic they work.

I even saw a guy who built a larger version of a star fractal using copper and brass as a literal art object in his wife's upper scale living room, which looks modern and great, and secretly hid the balun and R6 cable running to it as it acts as a functional antenna too.

Starting when I was in college with desperately wanting to pull in FM signals from cities 60 or 70 miles away, I started studying every antenna design book I could get my hands on. Also, at the time I was an avid Amateur Radio Operator, so Antenna design and signal DB gain or loss was not only interesting to me, it was super important.

One of the best VHF Antennas I ever built was the DisCone. Worked great as a 2 meter transmitting and receiving antenna, and as an excellent FM and VHF reception antenna. They are fairly small. Radioshack used to sell them (Maybe they still do?).
And then there is the simple Dipole. I think they work great, but I prefer the omnidirectional gain you get from the DisCone.

I also remember when Cable TV companies offered an FM tap, and had 20 or 30 clear as a bell FM Stereo stations at your disposal. I kind of miss that, since it made your FM tuner really sing!

BillyBatts said:

Starting when I was in college with desperately wanting to pull in FM signals from cities 60 or 70 miles away, I started studying every antenna design book I could get my hands on. Also, at the time I was an avid Amateur Radio Operator, so Antenna design and signal DB gain or loss was not only interesting to me, it was super important.

One of the best VHF Antennas I ever built was the DisCone. Worked great as a 2 meter transmitting and receiving antenna, and as an excellent FM and VHF reception antenna. They are fairly small. Radioshack used to sell them (Maybe they still do?).
And then there is the simple Dipole. I think they work great, but I prefer the omnidirectional gain you get from the DisCone.

I also remember when Cable TV companies offered an FM tap, and had 20 or 30 clear as a bell FM Stereo stations at your disposal. I kind of miss that, since it made your FM tuner really sing!

Click to expand...

Here's a table that shows the frequencies of VHF and UHF TV (FM is just above channel 6 VHF low). The infamous Channel Master 8 bowtie supposedly got some VHF high reception (7 - 13) but that may have been just because it had so much aperture / metal. The Grey-Hoverman may be neither fish nor fowl when it comes to FM. With the omni DisCone he would not have to worry about a rotor in his attic. That's all I know, never worked above 20 meters, LOL. Anyhow that's my lousy two cents.

http://www.csgnetwork.com/tvfreqtable.html

loopstick said:

Here's a table that shows the frequencies of VHF and UHF TV (FM is just above channel 6 VHF low). The infamous Channel Master 8 bowtie supposedly got some VHF high reception (7 - 13) but that may have been just because it had so much aperture / metal. The Grey-Hoverman may be neither fish nor fowl when it comes to FM. With the omni DisCone he would not have to worry about a rotor in his attic. That's all I know, never worked above 20 meters, LOL. Anyhow that's my lousy two cents.

http://www.csgnetwork.com/tvfreqtable.html

Click to expand...

That's a cool chart! Thank you!

loopstick said:

Here's a table that shows the frequencies of VHF and UHF TV (FM is just above channel 6 VHF low). The infamous Channel Master 8 bowtie supposedly got some VHF high reception (7 - 13) but that may have been just because it had so much aperture / metal. The Grey-Hoverman may be neither fish nor fowl when it comes to FM. With the omni DisCone he would not have to worry about a rotor in his attic. That's all I know, never worked above 20 meters, LOL. Anyhow that's my lousy two cents.

http://www.csgnetwork.com/tvfreqtable.html

Click to expand...

LOL.
The DIY DisCone is definitely not convenient or something you want in your house. Not as easy to make or cosmetically 'cool' as simple DIY fractals either. Fractals work great for FM and just about anything. Break open your smartphone and take a look.

I've had a chance to look into fractal antenna stuff. I didn't spend too much time on it (when the computer went to DST it was kind of a shock), but I think this topic is worthy of a "cutting edge" type discussion. It involves the DIY crowd, but I think the conceptual and theoretical aspects would be most efficiently discussed in a single "cutting edge" type thread. Stay tuned. I'll be back shortly with the link.

edit: Here's the link:

http://www.audiokarma.org/forums/showthread.php?t=580253

Enjoy

Loopstick, we are on the same page, you are just a little ahead of me time wise.

Some basic information regarding the discone antenna and fractal antennae.

Going back to the discone antenna, the best theoretical gain for a discone type antenna, in general is less than 3 dB (actual gain over a dipole) and that is somewhat frequency specific. In general over most of the frequency coverage range it is about the same or a less sensitive than a dipole antenna.

Its main claim to fame is its broadband nature.

A fractal antenna is an antenna that uses a fractal, self-similar design, to maximize the length of the elements per unit of area.

Fractal antennae are a special, small aperture case, of the more general “meander line” antennae. They add distributed capacitance and inductance in an unconventional manner.

The basic design has been around for a long time, dating back to the 1920s, although it was in a simple, basic form (self similar design). and had not yet been named a fractal antenna. See the first picture. Note the current direction and amplitude.

The second picture is a simple fractal style antenna representation.

Note the similarity to the “Hoverman” style of antenna. See the third picture.

The Hoverman style of antenna is relatively easy and inexpensive to construct from a mechanical stand point. But since we are talking about UHF frequencies, one needs to be somewhat careful when it comes to the actual construction in terms of maximum performance.

These examples are on the simple end of the scale for fractal antennae.

The forth picture is a basic fractal pattern. Note how it is derived from a basic shape, similar to the shape from the antennae of the 1920s.

The fifth picture is an example of a shortwave antenna that is a self similar design and resembles a fractal antenna.

The six and final picture is an simple FM broadcast band fractal antenna that I am modeling in software just for something to do.

Woooopppps, my medications got me, the pictures are in the cutting edge forum as linked to by loopstick.

Lots of good info, thanks. I'm going to do research into the DIY fractal approach.

You may want to follow some of us on the thread started by loopstick at the above link.

There is some very good information and some not so good information on the internet.

Take you time with your research.

Remember that with signal reception it is location, location, location and application.

You may run across those that will sing the praises of a particular design and then you will find out that they are all of 5 miles from the transmitters.

Most of the population of the USA live in a moderate to strong signal strength area.

So just about any piece of wire will receive there stations of interest.

JBL GUY said:

You may want to follow some of us on the thread started by loopstick at the above link.

There is some very good information and some not so good information on the internet.

Take you time with your research.

Remember that with signal reception it is location, location, location and application.

You may run across those that will sing the praises of a particular design and then you will find out that they are all of 5 miles from the transmitters.

Most of the population of the USA live in a moderate to strong signal strength area.

So just about any piece of wire will receive there stations of interest.

Click to expand...

+1. Do your research. Even simple research. Simple fractal antennas, especially easy DIY, can be found everywhere on the net.

FYI- I am 44 miles from the nearest HD FM broadcast antenna in a cluttered metro. Dumping all the factory made name brand antennas I ever had for DIY fractals is one of those rare best things Ive ever done.

Been perusing this design:

http://www.diytvantennas.com/sbgh.php

So, my understanding is that these are directional. Will something like this give me a fairly wide degree of reception, of will it be pretty specific?

unchained527 said:

Been perusing this design:

http://www.diytvantennas.com/sbgh.php

So, my understanding is that these are directional. Will something like this give me a fairly wide degree of reception, of will it be pretty specific?

Click to expand...

My laptop went down last night, so I have been busy rebuilding it.

That was bad enough, but my internet connection was down for about 11 hours and we had a power fluctuation while I was doing a back up and I lost some files, some of which were the data I had entered for the models of the Hoverman antennae and the fractal antennae.

If you have used antenna modeling software you will know what this means. The antennae that I was had at least 250 wire segments per antenna and the fractals had a lot more.

So it may be awhile before I get back to antenna modeling.

I still have a fair amount of software to install and that will come first. I just got 2 of my email accounts back up in MS Outlook.

OK, enough of that, but I will say it is nice to be back.

Now to your question.

One of my rough simulations (for the Hoverman style antenna) indicated a beam width of about 30 degrees and one that I built (not this simulation)measured roughly 40 degrees at the -3dB points.

3 dB may not sound like much, but it is the half power point. That is the point off axises where this signal drops by half.

For digital TV use, that could be a factor. In general a digital TV tuner is going to want to see at least -80 dBm of signal with a carrier to noise ratio of about 15 dB. Of course there may be variation between models, and brands of TVs.

That is, a digital TV will work OK down to a point and then if the signal drops a dB or so below that point then there are the much loved pixels and then no picture.

As I often repeat with signal reception it is location and application.

My fall back recommendation, because it supplies not only direction of the signal but a good estimation of the RF field strenth is...

TV FOOL

If you leave off the foil reflector , as shown in the link, it will reduce the gain and it becomes bi-directional.

It is an easy antenna to experiment with...

To add more information about the possible importance of the beam width of an antenna, look at the picture below, part of signal strength chart from the TV Fool web site.

Notice the point at which the charge changes color, right at the -80 dBm signal strength point.

So if a person had a signal strength of - 79 dBm on axis but the station of interest was at 25 degrees off axis, then that would drop the signal by over 3 dB and probably drop it below the threshold of usability.

This is only one example, the actual performance of any antenna that one builds will depend a great deal on the correctness and accuracy of the construction.

Someone ask about using this design for the FM broadcast band.

The basic design that is found on the internet starts to fall apart below 150 Mhz, although the antenna will still have some gain and a reasonable signal pattern down to 175 Mhz, which is the frequency for TV channel 7.

That means this antenna could be used for TV vhf high band channels (with some reduced gain compared to the UHF frequencies) and TV uhf band channels.

Here is what a generic Hoverman antenna looks like at in the FM broadcast band at 100 Mhz,

Basically it just looks like an ordinary dipole antenna.

loopstick said:

You didn't happen to dump them anywhere in Western New York?

Click to expand...

Pardon, stalker ?

JBL GUY said:

Someone ask about using this design for the FM broadcast band.

The basic design that is found on the internet starts to fall apart below 150 Mhz, although the antenna will still have some gain and a reasonable signal pattern down to 175 Mhz, which is the frequency for TV channel 7.

That means this antenna could be used for TV vhf high band channels (with some reduced gain compared to the UHF frequencies) and TV uhf band channels.

Here is what a generic Hoverman antenna looks like at in the FM broadcast band at 100 Mhz,

Basically it just looks like an ordinary dipole antenna.

Click to expand...

Who ask you about the G-H for the FM broadcast band, specifically?

The Grey-Hoverman is more for directional HD TV.

The more common fractals out there, such as the laymens 'star' designs, in about a thousand different versions, work excellent across the entire FM band. I'll never buy another overpriced, name brand, factory made antenna again. When performance like Im getting now is just a little elbow grease and designs that look artistic too.

KKnight said:

Who ask you about the G-H for the FM broadcast band, specifically?

The Grey-Hoverman is more for directional HD TV.

The more common fractals out there, such as the laymens 'star' designs, in about a thousand different versions, work excellent across the entire FM band. I'll never buy another overpriced, name brand, factory made antenna again. When performance like Im getting now is just a little elbow grease and designs that look artistic too.

Click to expand...

It has been asked about in previous threads, here and on other forums. My specific reply was prompted by an email from a friend that is following these threads.

I am sharing information regarding the basic Hoverman style (self similar) antenna design and it performance at various frequency ranges.

I am well aware of the fractal antenna, its design and uses. As I mentioned I was in the processes of modeling some of the fractal designs, but ran into a computer/loss of files issue.

It takes a fair amount of time to enter the data needed to model an antenna and it may be awhile before I am able to get back to it.

If you missed it, here is a LINK to another thread about this topic to a somewhat parallel discussion in a different thread.

You make a good point in your post and my post indicates that the basic Hoverman style antenna may not be the best suited antenna for the FM broadcast band.

As I posted before the Hoverman style antenna is a very simple form of a "self similar" antenna design. Being self similar is the basis of fractals and fractal antenna design. Exploring the operation of the Hoverman antenna may make it easier to understand the operation of fractal antennae.

Since most here are not antenna engineers, I started with the simple first.

My intent is to explore the design and application and help those that might like to build one, avoid some of the common pitfalls.

There is much more to designing an optimum performing antenna, fractal or otherwise than just putting some bends in pieces of wire and calling it an antenna.

As I have mentioned before, most of the population in the USA lives in moderate to strong RF signal strength areas and as such, even a poor antenna may, to quote you, "work excellent".

I have modeled, built and measured the performance of some of the designs found on the internet. Some take a good design and then compromise the performance in the method of construction.

As you mentioned, there are a lot of plans "in about a thousand different versions" to quote you, for fractal style antennae on the internet, some much better than others.

One that I found on the internet was a good design but in the construction, the builder used large fender washers to mount the antenna elements, not understanding that the spacing of the washers and area taken by the washers negatively impacted the operation of the antenna by creating unwanted lumped impedance constants within the antenna elements.

If you would not mind, could you post some information and or pictures of the antennae that you find work well for you?

loopstick said:

The FM band is just above HD TV channel 6. In fact it's between HD TV channels 6 and 7. Therefore an antenna that works for directional HD TV should work fine for HD FM. But if you want color FM, you're going to have to fractalize one of these babies:

Click to expand...

One has to pay attention to the antenna type. Since the transition to digital over the air transmission most of the TV stations have transitioned to the TV VHF high band that starts at 175 Mhz and the UHF that starts at 470 Mhz.

These antennae will have very poor performance in the FM broadcast band.

The length of the elements will be too short and the inter-element spacing will be incorrect.

When looking at the length of the elements for the FM broadcast band, especially above 98 Mhz, it will be seen that the shortest element length on a TV antenna that covers the VHF low band which includes TV channel 6, will be to long for optimal performance.

I understand that some have used TV antennae for the FM broadcast band, but it would not be my first choice.

I got a chuckle from your picture. Hey I have designed and built an antenna that actually does allow me to receive FM broadcast band signals in color. It is super secret...

I understand that some TV antennae are designed to have coverage of the FM broadcast band.

But in general sensitivity to signals in the FM broadcast band was discouraged to help prevent FM interference with TV channel 6.

Those that understand antenna operation can determine if an existing TV antenna will give adequate performance in the FM broadcast band.

I share this information for those that do not have this understanding and might question using a TV antenna for the FM broadcast band.

If a person already has a TV antenna in the air, there is no harm in giving it a try.

But that is a lot of aluminum to put in the air just for possibly questionable FM reception.

Yes, please share the brand and model and other information on your antenna.

By the way, for those that do not know that is Kurt N. Sterba, a play on the Sterba curtain antenna.

Below is a diagram of a Sterba curtain antenna.

Thank you and others for your posts. I am glad that were are able to keep this thread and the Fractal antenna thread alive.

To paraphrase, may force of the RF field strength be with you.