VHF Low Reception

Will62

Thread Starter
Member
May 20, 2011
14
1
Missouri
Real Channel 5. Field Strength in DB is 38.11 and the Noise Margin is 10.11 according to the Rabbit Ears Signal Analysis Tool. Probably a 2 edge signal. Antenna height is at 25 feet above ground level.

Thought that purchasing a J55 from Wade cut to Channel 5 but wondered if purchasing something like a Channel Master Masterpiece 100 or Winegard 8200 might be sufficient? Any other options to consider?
 

primestar31

SatelliteGuys Master
Lifetime Supporter
Mar 15, 2005
8,825
5,233
Beta Omicron Delta III
Sure, raise the height of your antenna. Or maybe even lower it. You can never tell with a possible 2-edge signal. I'd try at least another 10' height increments. You'd also do well to eliminate all possible sources of electrical noise within 300'. Switching power supplies, led bulbs, battery chargers, etc.

Though since you haven't posted a Rabbitears report for your site, I can only guess. RabbitEars.Info
 

Will62

Thread Starter
Member
May 20, 2011
14
1
Missouri
Will the published gain specs of any of these antennas be adequate to receive the signal strength I reported?

I have found the Rabbit Ears Signal Analysis to be unreliable. I have tried it for several locations and often times it changes for the same location. I don't see that with TV Fool or the FCC DTV tools. Since Rabbit Ears is still a Beta from what I read, it still has some bugs that need to be worked out. From the FCC site.

RF Channel: 5
RX Strength: 39 dbuV/m
Tower Distance: 74 mi; Direction: 5°
 

Tower Guy

SatelliteGuys Pro
Nov 1, 2005
678
56
Before you even start considering a good antenna, try listening to your car radio on 530 KHZ while you drive by your house. If you hear the noise level rise in the vicinity of your location, there is line noise that would need to be fixed by the power company.

10 dB of noise margin is usually too little for low band reception. I know that TVfool does not consider the 4 dB of NM that the FCC subtracts due to noise. I believe that the rabbitears NM calculation does so, but I have never verified it.

In order to offer a recommendation , I would consider the terrain in front of your antenna, the distance to the nearest hill in the direction of channel 5, and the height of that hill. With this data, it would be possible to calculate an optimum height to install a channel 5 antenna. Such an install would add 6 dB of ground gain, which would be necessary to override low band noise levels.
 
  • Like
Reactions: FTA4PA

Radioguy41

SatelliteGuys Pro
Aug 7, 2008
1,775
1,258
Lehighton, Pennsylvania
Nothing you can do is going to compensate for a too small antenna. The lower the frequency the larger the antenna needs to be so think big then add a mast mounted pre-amp. Keep this in mind, there is an anomaly known as knife-edge-refraction which means the TV signal will bend downward at the crest of a hill so that's where you want to point the antenna.
 

Trip

RabbitEars Webmaster
Staff member
HERE TO HELP YOU!
Jun 21, 2008
1,270
673
Alexandria, VA, US
I have found the Rabbit Ears Signal Analysis to be unreliable. I have tried it for several locations and often times it changes for the same location. I don't see that with TV Fool or the FCC DTV tools. Since Rabbit Ears is still a Beta from what I read, it still has some bugs that need to be worked out.
Hm. Claims it is "unreliable" and "has some bugs," fails to report said bugs or how to reproduce them, but expects them to be magically "worked out" without providing any information to facilitate that process. Seems fair.

In any event, in the absence of providing a link to your RabbitEars report, it is very difficult for people here to provide advice beyond the generalizations you've already seen here. I'm going to guess your problem station is WOI; if so, do you get the other Des Moines stations? KCWI provides a copy of WOI's primary programming on 5-5, which may help things.

But it is likely that you won't know the result of attempting to recieve actual WOI signal until you try. While UHF predictions tend to be reasonable in many cases, due to the variability of local noise, VHF predictions (and especially low-VHF predictions) can vary from "pretty close" to "way off". I agree with others who suspect that 10 dB of margin is probably not enough, but it's hard to say with certainty.

- Trip
 

Tower Guy

SatelliteGuys Pro
Nov 1, 2005
678
56
If the station is WOI, 74 miles away at 5 degree aiming direction would be Dean, Iowa.

 

Will62

Thread Starter
Member
May 20, 2011
14
1
Missouri
Rabbit. I supplied the same Lat and Lon for the specific home several times. Initially I got the same report. But the last three times something different showing no reception at all.

I don't own the home but I am going to look at later this week. Will check out the AM dial as suggested and in fact I planned to do that since I listen to AM frequently.

Yes, it us WOI in Ames.
 

Will62

Thread Starter
Member
May 20, 2011
14
1
Missouri
I should add that the line of sight to the north of the home is clear at least from what I am seeing on Street View. I am thinking about buying it. Will definitely use a pre amp of course. Going by the first report which I didn't save in Rabbit Ears the only really challenging signal is WOI. The remaining channels that can be received including 8 and 13 should be OK though weak. NM on both is 7 plus and 8 plus. Figure my old Y10-7-13 from Antennacraft should work for that.
 

Will62

Thread Starter
Member
May 20, 2011
14
1
Missouri
Here's the latest report. Not the same one that I received the first few times I tried it. Same exact Lat and Lon each time. This conflicts with both the FCC site analysis and TV Fool. Both show reception of at least 6 Des Moines stations.

 

Trip

RabbitEars Webmaster
Staff member
HERE TO HELP YOU!
Jun 21, 2008
1,270
673
Alexandria, VA, US
Rabbit. I supplied the same Lat and Lon for the specific home several times. Initially I got the same report. But the last three times something different showing no reception at all.
Here's the latest report. Not the same one that I received the first few times I tried it. Same exact Lat and Lon each time. This conflicts with both the FCC site analysis and TV Fool. Both show reception of at least 6 Des Moines stations.
I just looked at the backend database for all the reports sharing the coordinates of your posted report. I see eight of them with varying receive antenna heights and search distances. Changes in search distance will impact which stations are included in the results, while changes in height will impact the field strength calculations. Additionally, the reports seem to have been run over a period of several weeks; to the extent that any of the stations made any changes (not that I think many, if any, did), that would also impact the results.

Six of your eight results appear to have used 60- or 70-mile search distances. (The most recent one, it appears that someone, probably Tower Guy, bumped it up to 80 miles using the drop-down option.) Since most of the Des Moines stations are 74-76 miles away, naturally those stations don't appear in those results.

- Trip
 
  • Like
Reactions: Tower Guy

Mister B

SatelliteGuys Pro
Pub Member / Supporter
Jun 3, 2008
303
121
El Paso County Texas
[
The remaining channels that can be received including 8 and 13 should be OK though weak. NM on both is 7 plus and 8 plus. Figure my old Y10-7-13 from Antennacraft should work for that.
The Y10-7013 was one of the best antennas I ever purchased. It made a huge difference back in the analog days. I wish I could have kept it. If it is not satisfactory for your channels 8 and 13 I suspect nothing would be.
 

primestar31

SatelliteGuys Master
Lifetime Supporter
Mar 15, 2005
8,825
5,233
Beta Omicron Delta III
I'm using a Y10-7-13 antenna right now, dedicated to my one VHF channel that's on RF12, but only 37 miles away. I have a new spare stashed in a box, if this one ever gets damaged.
 
  • Like
Reactions: FTA4PA

Tower Guy

SatelliteGuys Pro
Nov 1, 2005
678
56
(The most recent one, it appears that someone, probably Tower Guy, bumped it up to 80 miles using the drop-down)

- Trip
Correct, I changed it to 80 miles. I was not aware that my edit would change the results to 80 miles for everyone who clicked on the link. That’s a nuance I did not expect, but is a useful result.
 

Will62

Thread Starter
Member
May 20, 2011
14
1
Missouri
Maybe the TV Fool Report for this location will help. I am guessing that this may still be fairly accurate since I didn't see any of the channels available as part of the Repack.

 

Will62

Thread Starter
Member
May 20, 2011
14
1
Missouri
I tried the Rabbit Ears Signal Analysis again and it now functions properly when I have it set at 80 miles. Here is the report at 30 feet. Differs from the TV Fool Report.

 

Jim5506

SatelliteGuys Master
Pub Member / Supporter
Lifetime Supporter
Oct 19, 2004
6,952
1,600
Lubbock, Texas
At your distance height and obstructions are your biggest enemies. The TVFool propagation map shows the area to be very spotty even from one house to the neighbor's house the signal can go from poor to none.

If there is any way you can get you antenna up to 45 -50 ft. that appears to almost double your potential signal from WOI.

I use the mapping facility (right side of the page) in TVFool.

While their database may be out of date, it still shows me where hot spots are for a station's signal and lets me easily adjust my antenna height to see how helpful greater elevation is.

Clicking on the radio button before each station in the list shows that stations calculated radiation profile. Moving from purple to dark blue can potentially double your signal.
 

Will62

Thread Starter
Member
May 20, 2011
14
1
Missouri
The one positive factor at the moment is that the home faces north and I noted that there is nothing across the street that blocks the signals. Just a large garden. Nearest building appears to be a block away.

Not sure if zoning will allow a tower of that size on that property. Guessing I can do 30 feet but not much else but I can check with zoning before I make an offer on the home. I have a year to work on this. Even if purchase it this Summer, it will be a year before I relocate. Can perhaps figure this out by that time.

What would be the best pre amp for this situation? I know a low noise floor is best. Finding one that works well for VHF low is essential.
 

Users Who Are Viewing This Thread (Total: 1, Members: 0, Guests: 1)

Latest posts

Top