Thanks in advance to those who provide assistance. I had lots of experience installing antennas, but that was back in the 1970s, so I thought it best to seek some current advice. ;-)
I’m replacing a storm damaged antenna at my mother’s house in Mississippi. We need to pick up six stations 50 miles away in Jackson on RF 12, 20, 21, 30, 40, and 41 which are nicely grouped within ten degrees of each other. RF 34 might be good to have, but it is 60 degrees off from the others and is definitely optional (CW). Based on the frequencies, we need high band VHS and strong gain on the low end of the UHF band for RF 20 and 21 (since RF 30, 40, and 41 are substantially stronger).
The existing system is a large VHF/UHF antenna about 20-25 feet AGL with pole mounted preamp and a distribution amp feeding four TVs through a drop-tap system (with inactive drops bypassed). I believe the antenna is from the Channel Master Crossfire line. After jury-rigging a long pole to push the VHS elements back out into place, I’m actually getting good UHF reception despite the UHF section of the antenna being bent down at a 40 degree angle, but I get no reception on RF 12. The house is on level ground at 200 feet elevation with tall trees to the north in the direction of the transmitters.
I’ve linked
results based on 30 feet AGL since that seems to be the most likely approach. Trying different elevations showed that 30 feet AGL gives LOS for five of the six stations; getting LOS on RF 21 requires going to 56+ feet which I don’t think is feasible.
For comparison, I’ve also included
results at 20 feet AGL, which has LOS for three of the six and 2Edge paths for two. Going to 25 feet gives stronger signals but the same paths.
Questions:
Does having the “1Edge” path versus LOS have any impact on reception beyond strength? I see that going from 25 feet to 30 feet gives a 9 dB jump for RF 20 and 4.2 dB for RF 12 when they gain LOS while only increasing the three channels that were already LOS by about 1 dB.
What is our “target” NM level? I've read the Signal Analysis FAQ, but I'm not sure I've got it. A
baseline radar plot with no elevation entered shows the six target stations with NM levels ranging from 17.7 to 24.2. It
sounds like I should be able to get all six with just an attic antenna, so I'm confused.
Am I overestimating how much antenna I need based on what we used in the analog days? I was surprised by the UHF reception; only RF 21 was relatively weak (about 70 percent on a simple strength meter on a conversion box IRRC), though we do have substantial amplification.
SolidSignal.com recommended their HDB8X, but would that provide sufficient gain on RF 12?
Is it better to go with a combination high VHF/UHF antenna or separate antennas, such as a Y10-7-13 for VHF ($38) paired with a Winegard HD9032 for UHF ($32)? That looks like 9.6 gain for VHF and 14.9+ for UHF.
Thanks for letting me draw on your experience! I definitely need help.
30 feet AGL:
http://www.tvfool.com/?option=com_wr...46aee0ab95fe6a
20 feet AGL:
http://www.tvfool.com/?option=com_wr...46ae4f212840e8
Baseline:
http://www.tvfool.com/?option=com_wr...46ae8505f27f97