Antenna best reception not in front

[mars1162]

I have been trying different directional antennas. I have never run into this problem before but this antenna receive pattern seems to be off about 30 to 35 degrees. The receive patterns seems to be off to just one side of the front of antenna. The antenna is a Televes DAT BOSS MIX LR uhf/vhf. The stations that I am receiving this way are the ones that are over 40 miles away. The closer one have full signal meter reading on the Samsung tv. I have sent pic of antenna and any reasons why would be helpful. Thanks John PS I did look up the physical locations of those stations to make sure I was pointed in correct direction.

[rabbit73]

Hello, John



From your photo it looks like you have the 149883 Kit, which is the 149821 antenna + the PSU-550104 power supply/power inserter.

You haven't shown us your TVFool report, but if your other antennas didn't act this way, my guess is that the preamp in the antenna is being overloaded by strong local signals. When you rotate the antenna, the overload is reduced and you are able to receive the weaker signals.

The preamp in that antenna is unusual. When you remove its power, it goes into bypass mode. Try unplugging the AC power from the power inserter, or completely removing the power inserter.

From the Solid Signal Technical document:
https://www.solidsignal.com/pview.asp?p=149883

http://forums.solidsignal.com/docs/H...n%20149883.pdf

That’s why the DATBOSS Mix LR is passively amplified, and it’s one of the few antennas on the market that is. Most amplified antennas won’t work at all if they’re not powered, but the DATBOSS Mix LR will. If you don’t need an amplifier, don’t use it.

The DATBOSS Mix LR includes this power injector that sends power up to the amplifier and also lets you run up to 2 TVs without adding an additional signal. It plugs into the wall inside and safely does its job. If it becomes unplugged, the antennas will still function and the power supply may be completely bypassed if you don’t feel you have a need for amplification. If you are less than 30 miles from broadcast towers or if you see odd interference on many channels, you may not need an amplifier and may be better off without it. It’s your decision. While this power injector looks like Televes’ own distribution amplifier, it does not have any amplification within it. The amplifier assembly is located within the antenna itself.

From the Product Manual:
https://manuals.solidsignal.com/149883_manual.pdf

[mars1162]

Thanks for the info Rabbit73 ! One of the reasons that I decided to try this antenna was the passive amplifier! I think it is the only one I have found as of yet that the preamp mounts at antenna and you can still turn off the amp or not. I have not tried heading antenna in the direction of further stations with the power to amplifier off to see if this corrects the problem of stations signal strength being to one side of antenna . I will try that shortly. The last antenna I tested was denny's HD stacker and did not have that problem with it BUT I did not have it amplified.

[ADTech]

In order to advise you we need 1) your TVfool plot and 2) the specifics of WHICH stations you are experiencing this phenomenon. Without that very BASIC information, there's not much we can do except sit around and chat.

"Passively amplified". Hmm, that's a real oxymoron, probably created by some marketing genius. Seriously, it's either amplified or it isn't. Now, if they'd called it a by-passable amplifier, that would make sense.

FWIW, that amplifier module has an automatic gain control that cuts gain very significantly in the presence of strong signals. It's frequency vs gain response is pretty nasty when that feature kicks in making it okay on some channels and severely reduced on others.

If you're aiming the antenna directly at a strong signal, then it's probably automatically reducing amplifier gain and causing a significant reduction in signal power until you aim it far enough off-axis for the gain-limiting circuit to relax and for the amp to go back to full gain.

[rabbit73]

mars1162:

Yes, I also would like to see your TVFool signal report to help me understand your reception problem and learn a little more about the Televes preamp that has AGC.

Originally Posted by mars1162

WFIE is not showing on my channel search on TV Fools signal strength map with all the other stations in my area. It is about 13 miles from my location. Their tower is located in Henderson KY on Wolf Road. It is listed locally as channel 14 on a 1000 foot transmitting tower. It may really be on channel 26

You are correct, it isn't on the TVFool report. I picked a location at random in Henderson:
http://www.tvfool.com/?option=com_wr...9038260d5e86fe



and then I used the same location for a rabbitears.info report which shows WFIE NBC (the page takes a long time to load when signal strengths are requested):
https://www.rabbitears.info/search.p...=dBm&height=25

[mars1162]

Ok here is my TV Fool Report http://www.tvfool.com/?option=com_wr...9038b9ec20c134 Rabbit73 & ADTech Antenna worked as should as far as receiving best dead in front with the amplifier on antenna not powered. Or shall we say bypassed. I did lose 2 stations without amp on. They are WSIU Carbondale IL and WTUV Vincennes IN. WSIU is not on my plot map. Virtual 16 and actual 19 I think. You guys were right I think about the variable gain on amp causing the signal to seem skewed on antenna.Thanks a bunch for the info and help.

[rabbit73]

Thank you for making the test and for the TVFool report. Your report shows WTVW with a signal power of -2.2 dBm highlighted in red, which is an overload warning. A preamp is contraindicated unless you insert a custom filter before the preamp to attenuate real channel 28.

I had been wondering about the Televes preamp that adjust the gain. It might work at a location with all weak signals or all strong signals, but with a mixture of weak and strong signals, it is the wrong choice. Your location was ideal for the test; it showed the weakness of the concept. We appreciate the report of your experience; it will help us when giving advice to other posters.

The best clue you gave is when you said you had to rotate the antenna off-azimuth. That reminded me of a case in Las Vegas. The poster was using one of those cheap "150-mile" antennas that also have a preamp with waaaay too much gain. He also had to aim off-azimuth to prevent overload. The only reason to use a preamp with that much gain is when you have a very long coax line after the preamp to compensate for the signal loss from coax attenuation.

[mars1162]

Ok I see your point on the signal being overloaded from real channel 28. I have wondered if you or anyone else for that matter have ever tried using a variac on the power supply to the antenna preamp? I tried using it on the televes setup that I have and really don't see a drop in signal strength until I adjust it to 50 volts ac or less. I do have some adjustment on signal strength after that. I am not sure if this is because the voltage regulator in power supply is compensating for the low voltage and it quits functioning when volts fall below 50 or what. AGC circuit? I would like to try it on a titan 2 or something in that type of amp just for grins.. I think a truly adjustable amp gain at the antenna could be usefull...maybe maybe not??? THOUGHTS?

[rabbit73]

I did lose 2 stations without amp on. They are WSIU Carbondale IL and WTUV Vincennes IN. WSIU is not on my plot map. Virtual 16 and actual 19 I think.

WSIU is on your TVFool report, but it is not on your rabbitears.info report because it is more than 100 miles away. As before, NBC is not on your TVFool report, but it is on your rabbitears.info report. There is no WTUV; it doesn't exist.





Adjusting the voltage will not do what you want.

If you want to continue to use that antenna with its built in preamp and try to find results between amp IN and amp OUT, you would need to insert an attenuator between the antenna and its internal preamp. It would be a custom modification, not easily done.

I would like to try it on a titan 2 or something in that type of amp just for grins..

Your report indicates that a preamp should not be used. If you must use a preamp, it should be a medium gain preamp that is resistant to overload like the Antennas Direct Juice. Even then, you would overload your tuner and need to add an attenuator before the tuner.

What weak signals are important to you? When you have very strong local signals and you also want some weak signals, there will be a great difference between the two. Your system is only able to receive a limited dynamic range. You must tailor your signals to that limited range.

When your strong local signals begin to cause overload, it will produce IMD (Intermodulation Distortion) that will create spurious signals in the preamp and in the tuner. These spurious signals (spurs) raise the noise floor and wipe out your weakest signals because their SNR is reduced below the minimum required 15 dB.

The goal is to have just enough antenna gain and just enough preamp gain so that you can receive the weakest desired signals without causing overload from the strong local signals.

WTVW has a Noise Margin of 88.7 dB even before adding any antenna or preamp gain; clearly overload territory:



Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html

If are not happy with your present antenna with its preamp OFF and you want a system that gets weak signals at your location, you will need an antenna system like this:

antenna > custom CH 28 bandstop filter > attenuator if needed > overload resistant preamp > coax > grounding block > power inserter > TV

Grounding the coax with a grounding block connected to the house electrical system ground helps to reject interference.

You might also need an FM filter; you have some strong local FM signals that might cause interference to TV reception:
http://www.fmfool.com/modeling/tmp/d...9/Radar-FM.png

[mars1162]

WVUT Channel 22

Here you go Rabbit 73
Programming: PBS PBS

City: Vincennes, IN

Owner: Vincennes University

Station Info: Digital Educational Full-Power - 1550 kW

Market: Evansville

WVUT is a television station in Vincennes, IN that serves the Evansville television market. The station runs programming from the PBS network. WVUT is a digital educational full-power television station that operates with 1550 kilowatts of power and is owned by Vincennes University.

[rabbit73]

Umm, you typed WTUV, not WVUT in post #6; obviously a typo, John.

Originally Posted by mars1162

Ok here is my TV Fool Report http://www.tvfool.com/?option=com_wr...9038b9ec20c134 Rabbit73 & ADTech Antenna worked as should as far as receiving best dead in front with the amplifier on antenna not powered. Or shall we say bypassed. I did lose 2 stations without amp on. They are WSIU Carbondale IL and WTUV Vincennes IN. WSIU is not on my plot map. Virtual 16 and actual 19 I think. You guys were right I think about the variable gain on amp causing the signal to seem skewed on antenna.Thanks a bunch for the info and help.

WVUT is much weaker than your strong local signals. It got wiped out from overload AND it has possible adjacent channel interference from W23BV on real channel 23. The highlighted "a" next to the WVUT callsign in your report indicates adjacent channel interference; the highlighted "c" indicates co-channel (same channel) interference.

WVUT will be moving to channel 31:
https://www.rabbitears.info/market.p...&callsign=wvut

This is the point: Because of the very strong WTVW, you need a separate antenna and preamp, not an antenna with an integrated preamp. They must be separate because you need a filter between the antenna and the preamp to attenuate WTVW.

The only other alternative for your location is just an antenna with no preamp.

[rabbit73]

Here is the terrain profile for WVUT that shows how the signal is blocked by terrain and the curvature of earth:



The coverage map shows you are on the fringe. Note that only 21 kW out of 57 kW ERP is sent in your direction because of the directional pattern of the transmitting antenna:



closeup of coverage

[mars1162]

Hey Rabbit what is the 470' AMSL ? I am showing ground elevation at my antenna to be 493 feet and with antenna on a 40 foot pipe that would be roughly 533 feet above sea level. BTW I do get 22 out of Vincennes most of the time with the televes antenna with preamp on

[ADTech]

AMSL=Above Mean Sea Level

[mars1162]

Ok thanks for the info ADTech I had no idea...

[Antenna Medix]

Hi Rabbit73,
What terrain profile software are you using? I'd sure like to use that.
Thanks
Herb

[rabbit73]

Hello, Herb

I use HeyWhatsThat Path Profiler; it's the best profiler that I have found:
http://www.heywhatsthat.com/profiler.html

It was working fine with Internet Explorer 11, but suddenly now when I go to that site the page freezes. I have to switch to the Firefox browser to make it work. There isn't much in the way of instructions, but if you have a problem, I can walk you through an example.

When I go to the home page for that site, it doesn't freeze with IE 11.
https://www.heywhatsthat.com/

[rabbit73]

Originally Posted by mars1162

Hey Rabbit what is the 470' AMSL ? I am showing ground elevation at my antenna to be 493 feet and with antenna on a 40 foot pipe that would be roughly 533 feet above sea level.

To answer your question:

1. In order for me to run a terrain profile, I need to know the coordinates of the transmitting antenna and its height above ground level (AGL) and the coordinates of your antenna and its height above ground level. Since you haven't given me the coordinates for your antenna in a PM, I had to GUESS the coordinates for your antenna and enter them into the profile software.

2. Different sites will give different answers for the elevation of specific coordinates.

I got 432.0 feet from:
https://www.freemaptools.com/elevation-finder.htm

I got 433 feet from:
https://www.whatismyelevation.com/##
click on Change location to enter coordinates and press Enter

The site that I used for the profile gave me 430 feet before adding the antenna height of 40 feet above ground level (AGL):
http://www.heywhatsthat.com/profiler.html





If you send me the coordinates for your antenna in a PM, I can run it again. Or, you can run your own profile in the link just above.

I sent the coordinates I used in a PM to you.

I have no desire to argue with you about elevation or what antenna you should use. It is your antenna, your money, and your decision.

I was under the impression that you wanted to improve your reception, but apparently, you only wanted to know why the antenna aim was off; my mistake.

BTW I do get 22 out of Vincennes most of the time with the televes antenna with preamp on

If you are happy with your present reception, then you don't need any further help.

[Antenna Medix]

Thank you Rabbit73!

Herb

[rabbit73]

mars1162

Thank you for the coordinates by PM. My guess was only 150 feet away, so the profile is similar.

I am showing ground elevation at my antenna to be 493 feet and with antenna on a 40 foot pipe that would be roughly 533 feet above sea level.

The elevations from 3 sources for your location were 430, 433, and 433 feet, so I'm wondering where you got 493.

Originally Posted by mars1162

One of my goals I was trying to find a antenna that get the best possible signal on weaker stations with strong stations nearby.

That will not be easy, because there is a great difference in signal strength between the strongest and the weakest. Preamps and tuners have a limited range of what they can handle.

Your report for reference:
http://www.tvfool.com/?option=com_wr...9038b9ec20c134




Your FM signal report
http://www.fmfool.com/modeling/tmp/d...9/Radar-FM.png

The difference between your strongest signal and your weakest desired signal is call the Signal Dynamic Range. In your case, it is the difference between WTVW with a signal power of -2.2 dBm and WVUT with a signal power of -89.9 dBm, which is 87.7dB. To that, you must add the minimum required SNR of 15 dB for WVUT, giving a required SFDR (Spurious Free Dynamic Range) of 102.7 dB.



There are no preamps that have that kind of SFDR. The closest readily available preamp is the Antennas Direct Juice with a SFDR of 81.7 dB and a maximum signal input of -21.3 dBm, both of which are exceeded by the signals on your TVFool and FM Fool reports. The only thing that helps is when your antenna is aimed at WVUT, the strong signals in other directions are made weaker by the antenna pattern.



You will probably need a preamp because of your long coax feedline (how long is it?), but you might need to add an FM filter and an attenuator between the antenna and the preamp to keep it from being overloaded.