Antenna Question

[artto]

I have a stacked pair of large Wingard TV/FM directional antenna on the roof of my house. Nowadays I just use them for FM reception and as a possible backup for TV if its ever required.

The antenna are stacked, one on top of the other, about 4 to 5 feet apart. They are currently ganged together with a splitter/combiner. They are pointed in the direction of most transmission, towards Chicago, which is about 20 to 25 miles away.

One station is particular, WXRT 93.1 gets incredibly poor reception. I'm wondering if the stacked, ganged antennas have anything to do with this or if it's more likely I'm just in a null spot for that station.

In addition, there are are two large transmission antenna towers, one for WGN and WBBM, to the left and right, maybe 1 to 2 miles away in the direction the antenna are aimed. To make matters worse O'Hare airport is also in the direct path about 7 miles away.

Any solutions other than internet streaming? The only problem I have with streaming is it doesn't "match" the over-air broadcast - there is a delay. Not every receiver in the house is internet capable so it can sound a little weird for whole house background music.

[billybob]

When you say poor reception, do you mean that is popping in and out like digital off-air tv signal. First I would call station to find out if they are working on a fix themselves and are aware from others of a known weak signal issue.

Do you use an amplifier on the antenna system now?

They can be troubleshot. Patience and methodical approach is key.

For instance stacking is usually done for fringe/distant stations.

I have also used one type of off-air antenna combined with another for areas where the line of site to the stations differ.

Are all of the antennas pointing in the same direction?

Thanks

[cradeldorf]

With my rooftop antenna I couldn't get a tv station that was 25 miles away, It was because of the power amplifier hooked to the antenna. In other words it made the antenna too strong. the minute I unplugged it the station came in great. If you have an amp on the antenna I would try unplugging it and see if the station comes in good. Stacked gray hovermans are really good receptors.

Edited June 6, 2014 by cradeldorf

[minermark]

I went to Frys a few years back when the digital converison was the big thing, bought an "Oven Rack" UHF placed at roof top level, ran wire into the attic, 3-way splitter, plugged into three Tv's, and in the menu of each TV,Select air/antenna, hit auto program, 26 channels in digital HD is what we have, 15 more if you speak Spanish.

Frisco comes in at night 85 miles away also locked in digital.

Perhaps someone is still trying to get the VHF channels ? they are dead in the USA as of three years+ ago.

[billybob]

Sorry, I misunderstood. You are after an FM station that is weak. No, I do not see the interference from either the antennas you have or the other transmissions in your area. At least they should be out of band. But yes, always could be interference from them but, an adjacent broadcast channel sometime can interfere with a weaker signal next to it.

What type of interior setup are you using for FM?

Have you tried tweaking the analog signal at the antenna? Do you have a rotor for tweaking moving antenna?

Or, are you using a digital receiver for FM?

Thanks

Edited June 6, 2014 by billybob

[JJkizak]

I would just try the coat hanger bit on the receiver (any kind of wire or antenna) and if it works

then you have a problem with the stacked setup. All kinds of anomolies can happen with the stacked

combined setups.

JJK

[DrWho]

The 1/4 wavelength at 93.1MHz is 2.5ft, which would be the ideal spacing for diversity. Putting the antennas at 1/2 wavelength and just straight up summing together could give you phase cancellation depending on the multi-path behavior of the signal.

I think you would be better off with an RF switch instead of splitter/combiner (and just select the antenna that gives you better reception). Before buying a switch, you could just plug/unplug cables to see if it makes a difference.

As far as the other towers in the area - they should be out of band far enough that your RF front-end filtering should be providing ample rejection. If not, you could always add a passive lowpass.

Do you have any amplifiers in your setup? A strong outta band signal can cause the amps to clip - which will degrade performance at all frequencies.

[mark1101]

Go out to your car (in your driveway not garage) and turn on the radio.. Do you get the same behavior of the stations?

Also..........have you checked the integrity of your outdoor cable and connections? How old is all that stuff? Those cable F-style fittings are notorious for going bad outdoors and coax is suseptible to water migration which corrodes the center conductor and erodes the ground shield (braid)

FM is at the lower end of the VHF band where you need good metal to metal contact. I wouldreplace all the fittings and I agree with Doc and Mark to un-combine and use 1 good antenna. Get rid of any unecessary outdoor connections and the splitter.

[jason str]

I use Terk powered antenna and I'm my second one now, the first one fell from a shelf high up and broke. I'm in Arlington Heights now but it worked well in Mt Prospect, Des Plaines, Zion & Rockford pulling in all available stations and some i did not know were there.

Its adjustable and the trick is to keep it away from your speakers & other electronics as high up as you can get it, i listen to XRT sometimes and have no problems.

[artto]

Thanks everyone.

The reception usually has a large amount of noise. Sometimes its so bad even turning on FM mute for a semi-mono signal doesn’t get rid of it. At its worst the station intermittently cuts out.

There is no antenna amplifier involved.

Both of the antenna are pointing the same direction (they are directional antenna).

Originally, one antenna was used on the big screen TV up stairs in the living room, and the other antenna for the rest of the house since I didn’t consider it as critical. Years later, with the advent of cable service I decided to use the antennas for FM reception on the audio system (downstairs listening room).

Both antenna are quite large. They are roof mounted on a mast. Unfortunately I didn’t install a rotor. Since the house is a raised ranch (essentially 1 & ½ story above ground) I estimate the antennas are probably at least 18 to 20 feet above ground. They are quite large although they don’t look like it up on the roof. I remember putting them together in the garage and they looked quite large in the 2 car garage. Looking back on it, for the life of me I can’t imagine how I installed those things myself, but I did (crazy things you do when you’re young). The setup is large enough that it has to be guy wired by four cables.

They are quite old, cable, couplings and all (30+ years).

This happens on all four receiver/tuners I have as well as the Yamaha T-1 & T-2 I used to have. Current tuners/receivers are HK AVR130 (about 10 yr old), McIntosh MX130 (essentially a MR7083 tuner), NAD C446 Digital Media Tuner and Pioneer Elite SC-63, all good stuff. I would think any of these could resolve multi-path issues but the issue is the same with all of them.

I also connected the HK AVR130 to a Magnum Dynalab ST-2 omni FM antenna I had lying around and the same station still has the same issues. Granted, the antenna is sitting just above grade (foundation level, vertically) but it is on an outside wall (brick veneer) same side of the house the signal is coming from.

Its not doing it at the moment so I can’t check with the car radio. I usually listen to Sirius in the car so I haven’t been aware of it. This comes and goes. I know this seems weird, but the one thing that is pretty consistent is that its at its worst around 7-7:30 pm. At this time another station I listen to about 10 miles away, transmission received from the side rejection of the antennas does the same thing. It’s also a nearby frequency 90.9 does the same like clockwork. By 7:30pm its almost not listenable. It’s not a strong station to begin with (public radio broadcast from a community college). A few hours later everything is fine.

[cradeldorf]

You could try a loop antenna tuned to 1/4 wave of that freq. that's what I have. built it out of some 12 ga. solid core home wire.

[artto]

Correct Mark ~ my language mistake. The antenna is at least 18 to 20 feet above the ground (assuming about 9' per story plus the hip roof. 1-1/2 story = about 14 feet + 4 to 5 for the roof). The antennas are at the peak of the roof. The lower antenna, I'd say is probably about 2 to 3 feet above the roof, right at the top of the mast tripod at the very bottom of the mast, and the larger antenna is at the top of the mast which is another 4 to 5 feet higher.

So maybe disconnect the lower antenna & see what happens? Maybe its too low not only to the roof, but also too close to the mast tripod?

I never noticed anything bad about the picture quality when the larger, higher antenna was used for TV, but always had trouble with FM which was hooked up to the lower antenna. I guess I figured that since I no longer used either for TV I'd get better FM reception by combining the two, which may have actually made things even worse.

And like I said in the second post, yesterday there wasn't too much interference during the day, but like clockwork, by 7:30 pm the noise level had definitely increased to an annoying level.

[billybob]

Rotor then not necessary as stations after are covered by your fixed antennas.

All of the FM stations you listen to are acceptable except for the 2 effected, one of which you are after.

Are there any repeater/sister stations nearby broadcasting simulcast for this station?Which if so may be in a different compass reading and possibly an acceptable signal level. If so, try one of the antennas in that direction.

If not, and you want too, try one of these type amps with variable gain. Although it is for boosting the whole bandwidth and not the specific frequency of the stations, it could bring the target station up to snuff. A couple of db's boost can sometime work wonders. The variable gain comes in to minimize any overdriven effects to the stronger stations. Boosting the signal with amp may also raise the noise level you are already experiencing.

http://www.showmecables.com/product/25dB-V-U-FM-Variable-Gain-Distribution-Amp.aspx?utm_source=google&utm_medium=cse&utm_campaign=27-160-025&zmam=49733141&zmac=5&zmas=1&zmap=27-160-025&gclid=CPzpl_Gb6L4CFSsV7AodaFYA6A

If there is any improvement in signal quality but, not up to acceptable, you may want to try a 2 part amp system, consisting of a pre-amp mounted on the antenna, and the interior unit preferably with variable gain once again.

Notice, I am trying to keep you from roof climbing and ladders at first.

Trying out the signal from your car could let us know if dealing with a weak versus a stronger signal. If stronger, I would speculate it is simulcast and the bearing could be sought out.

The Winegard does a good job for us and is in a woodsy environment. It has a pre-amp type amp and is run into another 25db amp to boot, to deliver our weaker digital TV stations.

As for my tuner, I have a six foot strand of solid copper RG-6 coax as an interior antenna. The stronger nearby stations are at threshold and one I listen too occasionally is weak.

Each location being different of course but sharing common problems at times.

A simple test for me would be to run coax directly from antenna balun into my nearby tuner. If not acceptable, I would amp it and tweak.

It is a handy amp to have to help troubleshoot.

Certainly having multiple connectors/connections in line from the antenna to the tuner can result in longer runs and insertion loss per conection. Perhaps a boost will help.

What is happening at the clockwork times is, you are experiencing possible inband sidelobe interference, which the right filter may help with.

Edited June 7, 2014 by billybob

[artto]

I disconnected the lower, somewhat smaller antenna and put a terminator plug on it. The signal is much improved! And, I'm now getting the radio data info appearing on the recievers that support it. In the process I also discovered that the coax cable going to the music room from outside is damaged. About a 6 inch section has the insulation & shielding is partially torn off, right down to the conductor. The siding installers must have damaged it a few years ago when we had new siding installed. I'll have to pull a new line. The PBS jazz station to the south of me (right angle to the antennas) is still giving me a little trouble at the "clockwork" time around 7:30 pm. Maybe the new line will clear that up too. The signal to the main system in the listening room (with the damaged cable) is not quite as noise free as the one upstairs, but it's a whole better than what it was.

I really thought 2 antennas would be better than one, but I guess not, certainly not in this particular situation.

Thanks for all your help!

Edited June 8, 2014 by artto

[mark1101]

Sounds like you found the issue. It's a PITA to replace all the cabling and fittings but after 30 years and with the obvious damage it's almost certain you found your issue. New cable is shielded better as well.