As a code writer/editor, you well know that every decision involves trade-offs. That's every bit as true in RF signal propagation. The following comments assume that you want to pull in the major network affiliates broadcasting from Portland. The trade-off comes down to either:
1) Putting up a big tower and getting a single, near-fringe antenna capable of receiving VHF and UHF
OTA channels. A Winegard
HD-7696P antenna will be sufficient at this height.
2) Installing a mount on the house with a tall mast, perhaps steadied by guy wires, and using two of the most powerful antennas available, one dedicated to VHF channels 7-13, the other designed for the higher UHF channels. You'd want to acquire the antennas and pre-amp specified in the "
prescription for deep-fringe reception" if this is your choice.
As you probably appreciate, the second alternative will cost less. You won't need the rotor if the Portland stations are the only ones you want, but the pre-amp specified in the
prescription is a must with either setup.
I ran two TVFool reports at the provided coordinates -- one at 20 feet above ground, the second at 50 feet. At 20 feet, you have two ridges (the "2-edge" notations) to overcome. An extra 30 feet overcomes one of the ridges, but not both. The good news at 50 feet is that the signals are an average of roughly 20
dB stronger than those at 20 feet. That's a factor of 100.
Whether the trees block signals tends to be a matter of trial and error. They're not a factor at some locations, and they're a complete pain in the neck at others. Erecting an antenna (or two!) is the only way to find out which one applies to your situation.
Whatever you decide, I would strongly recommend against using a tree as a permanent antenna mount. (It's OK temporarily, for experimental purposes.) Trees have nasty habits that cut into reception and/or greatly shorten antenna life: They sway in the wind, which is murder on UHF signals in particular; they regularly drop sap, which corrodes the metal and can cause a reception-robbing short circuit; and the delicate aluminum will get mangled if a major branch falls on the antenna or the whole tree falls down.
