Transmitters 170 degrees apart!

[roybto]

Here's my tvfool report:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d5b94d680db23d7

The only transmitters I care about are the ones in the 290-292 degree range, plus KWPX (RF 33) at 121 degrees. (Well, I guess I'd also like RF 13 at 266 degrees).

I get all the channels I want sort of OK (occasional pixelating on some channels) with indoor rabbit ears connected directly to a TV, but I'd like to feed two or three sets, and have things work well in all weather, etc.

That RF 33 signal at 121 degrees has NF of 18.9, while the other channels I want have NF at least 20 dB greater. How about a directional antenna (maybe in the attic for starters, moved outside if necessary) pointed at 121 degrees, with all the powerful stations coming in the back? With an isotropic antenna I've got a 50+ dB signal intensity range, while if the antenna had a F/B ratio of 20 dB, the range would only be 30-ish dB. Since they are inexpensive, I'm thinking of a Winegard HD-9022, even if it's probably more gain than I need--I'm looking through some trees toward 121 degrees, so the directionality might help.

(I realize that RF 9, 11, and 13 are low VHF, but I figure they're so strong I'll get them even with a UHF-only antenna.)

--Roy

[GroundUrMast]

RF-22 is the exact same signal as RF-13... same program and bit-rate, same high quality feed of Fox network.

You may get some reception of High-VHF using a UHF only antenna... but there is more to reliable reception than just raw signal power... Poor impedance matching between the antenna and coax can produce very significant signal quality problems.

Most directional antennas will do a good job receiving from the rear. You can often aim toward the lower strength signal group and achieve reliable reception of the stronger signal group at the rear of the antenna.

Your report is based on a height of 12'... I've got a hunch you'll see a significant improvement if you run a report based on roof peak + 5'. Please consider posting a second TV Fool report. I'd feel more certain about a specific antenna recommendation once I've seen how signal conditions improve (or not).

[teleview]

I agree , please make and post a Tvfool report with the antenna height above ground of peak of the roof plus 5 feet.

[roybto]

GroundUrMast:

Here's the TVFool report at 17 feet AGL (5 feet higher than before, about 5 feet over the roof peak. This gives an increase of about 5 dB on the RF 33 signal that's the weakest:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d5b94efb5df18f5

Seems like elevation is worth a lot here. The house is a rambler with a low-pitch roof, hence the low elevation of the antenna.

(I actually wonder a bit about the exact details of the ground-level database in this case. The house actually sits about 6-8 feet higher than the street in front, so the exact elevation of the antenna may not be well resolved anyway.)

Thanks,
Roy

[ADTech]

I actually wonder a bit about the exact details of the ground-level database in this case.

Terrain data is averaged into 100 meter X 100 meter squares, then a calculation is performed on that averaged value. That's repeated for each square over the whole signal path. That's why playing with small increments in the simulator is usually "For amusement only" unless the area is pretty much flat as a pancake.

Ground clutter such as trees and buildings is not accounted for.

[teleview]

+=>
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Install a , www.antennacraft.net , HBU33 antenna aimed at about 250 degree magnetic compass direction.

Here is how to aim antennas , www.kyes.com/antennas/pointing/pointing.html

Use a Real and Actual magnetic compass to aim antenna.

---------------

A antenna system amplifier will most likely not be required.

----------------

Here are some above the roof antenna mounts.

www.ronard.com/909911.html
Use the , ronard(911) , 5 foot tripod antenna mount.

www.ronard.com/ychim.html
Measure around the chimney and use a , ronard(2212) , ronard(2218) , ronard(2224) .

Buy the ronard antenna mounts at , www.ronard.com
, or , www.amazon.com

[roybto]

At GroundUrMast's suggestion, I looked at slightly higher antenna heights for the tvfool calculation. I discovered that by going over about 22 ft. AGL, the weakest station of interest (RF33 near 121 degrees) suddenly goes from 1Edge to LOS. At the same time, RF33 NM value increases by more than 20 dB to become comparable to the weaker LOS stations from Seattle (at 290 degrees), in the 40+ dB range.

In reality, the elevation database (averaged over 100-meter squares, as ADTech has said) probably understates my elevation. I'm not on the top of the hill, but the downward slope increases pretty abruptly just to the northwest of my location. The RF 33 signal seems not significantly weaker than those 40+ dB LOS stations, so I think I'm getting LOS or close to it on RF 33 anyway.

The best antenna for me might be one with two lobes 180 degrees apart. In other words, some gain but a near zero front-to-back ratio. (Maybe one with a driven element in the middle, directors out both ends, and no reflector?) It might also be nice if RF 9 and RF 11 could be received.

Any suggestions for an antenna?

Thanks,
--Roybto