[Beefcake]

Hi all. I have been playing with antenna placement in my yard and I found a sweet area that can get 50% of the digital stations available. I then went to 100000watts.com and looked at power ratings. It seemed like the ones I am getting are 600kw+. So, I wrote a letter to a local stations (channel 39 UHF) and asked if they planned to up the power. He told me they were at the max power that the FCC would allow for channel 39.


I understand that as the frequency goes up, less power is required to get the same amplitude in the signal due to the shorter wavelength. It just seems weird that channel 30 is at 625KW, channel 42 is at 725KW, and channel 39 is only at 135KW.


Here's my question. I have trees in the yard. Other than that, I have a clear line of sight to the transmitting towers about 40 miles away. If after fine tuning the pitch and vector of the antenna, I still don't get the other channels, should I try stacking vertically(higher gain) or try stacking horizontally (fix multipath). Keep in mind that there is a guy about 4 miles away that has his antenna 60' up and clears the tree line. He gets all of the stations.


Is there a way to tell if the problem is signal strength or multipath? Thanks.


-Brian

 

[magic123]

Brian..


I would say..mostly, the problem is signal strength and the transmittsion of digital over UHF stations. I am hoping when digital goes back to mostly VHF in the future, everything will be somewhat better. Back in August my antenna (TelevesDat75) WAS LOOKING THRU A WOODS..and doing very well at distances of 18-36 miles. Of course, anything in the path cuts down on signal strength so it is very important to start out with a high gain, directional antenna with a rotator. To cut down on 'blocking' and 'dropouts' it is important to zero in on the signal. At 40 miles, 4 or 5 degrees can make a difference I have found. A clean line of sight helps the most, of course. In future, let us hope we have more sensitive tuners. And I feel sure the stations will learn more about sending out their signal. This is all quite new to all of us at this point in time. It will only get better.

 

[jckessler]

As frequency goes up, more power is required, not less. Shorter wavelengths do not propagate as well as longer ones, and higher power is required for equal coverage areas.


I asked the same question about Channel 39 power in another thread. Apparently their power is lower due to tower height.


In genreal, If you're getting ghosts on the analog channels, you have multipath. If you're getting weak reception (snow) you need more signal.


I think either a horizontal of vertical stack should improve gain.

 

[Gator99]

Brian, I was in the same boat that you were in up until this past weekend.


I was using an RCA 24 element UHF/VHF antenna on a 5' mast on top of my roofline which is 20 +/- feet high. I to have quite a few trees in my line of site, but I am only 12-18 miles from towers.


My old antenna was rated at 45 miles, but I was getting drop-offs in my signal from a couple of channels. This weekend I decided to see if it was multipath or signal strength, so I purchased the 31 element 60 mile range antenna and now my signal strength is pegged at 100% on all channels with no drop-offs.


Of course this is in Florida with no topography and Trees were my only problem.


Good luck

 

[jhe]

It can be very hard to tell if signal strength or multipath is the problem. Best way is with a signal meter or better a spectrum analyzer.


One thing you can try is to put in an attenuator, like about 6 db size. If the attenuator makes no change or makes things work better then it is more likely multipath. If it makes things much worse, then your signals are too weak.


This would not apply if you are close to stations where you have to consider overload as well!