Does passive reflection work?...

Posted 3/31/20 (Tue)

Watching TV or listening to FM radio from rural North Dakota can be quite challenging. You certainly need the right equipment to get a quality picture or radio signal.

It gets even more interesting when you have trees, buildings or mountains in your way. OK, no mountains in North Dakota, but think about people living behind large hills in the Badlands.

There are also those people who don’t necessarily live a long distance from a TV tower, but are in valleys and the signal goes right over the top of their heads and there’s nothing on TV. Remember, in the digital world either it’s a good picture, or it’s black.

So there is this phenomenon called passive reflection that is supposed to work for those who live in places like the Sheyenne, James, Missouri, Souris and Des Lacs River valleys.

According to the website TV Fool, the deepest fringe for TV is about 80 miles. If you have the right equipment, you can get TV within that range.

Suppose you live in a valley and are a long distance from a TV tower. Passive reflection is supposed to fix that reception problem.

Let’s say you live in the hills around Lehr. You’re 125 miles from Fargo’s TV towers, 100 miles from Bismarck’s towers and 80 miles from Aberdeen’s towers.

If it was my choice, I’d want to get TV out of Fargo simply because there are more channels.

You have an antenna on your house, so you point it northeast toward Fargo. But it’s not enough because there are hills in the way.

This is where passive reflection comes in. You go to a high spot toward the TV towers and set up an antenna pointing not just toward the towers, but right at them. You can get precise azimuths off the TV Fool website.

Just a few feet away, you mount another antenna that’s exactly like the first one. It’s same size, same brand name and most importantly, the same specifications. This time it faces toward the antenna on your house.

All you have to do is hook a piece of coax cable to both antennas, preferably quad-shield coax, maybe six feet long or more.

There’s nothing else, no electricity, no boosters, no pre-amps. Just make sure that both antennas are mounted tight enough so the wind doesn’t blow them into LaMoure  County.

The Des Lacs River Valley presents a challenge. Living between Minot and Kenmare for the past 17 years, I have always theorized that this would work, I recently found some information that backs up that theory.

Professors at Mackenzie Presbyterian University in Sao Paulo, Brazil are currently working on passive reflection, or as it is called in Brazil, passive reception.

It’s pretty simple really. The antenna pointed at the transmitting tower, receives or absorbs the signal, no matter how weak it is. That’s why it’s imperative to have good quality equipment.

The quad-shield coax, then sends that weak signal to the second antenna, which in turn, pushes out the exact same signal power that the first antenna received.

You can figure this all out in physics, or run mathematical equations through a computer and it spits out numbers.

Or, you can think of it this way. You are catapulting a weak TV transmission into the valley where you will most likely receive it.

Here’s the magical part of this equation. You don’t have to contact the FCC because you aren’t creating a signal, you are only enhancing the one that is already there.

If you add any kind of boosters to the antennas outside the valley, then yes, the FCC might be knocking on your door.

If you look at a topographic map of Brazil, you’ll know why they are studying this phenomenon. Much of that nation is rugged; forest, hills, mountains, jungle and vast wide-open spaces.

It stands to reason why they would want to figure this all out. The one thing I have yet to figure out is how far will that “pushed” signal travel?

Several enthusiasts who have done this in heavily wooded and mountainous northern British Columbia, say the signal will travel about 3 kilometers or just under 2 miles. Not bad for a signal that isn’t amplified.

But, my guess is it is dependent on how strong the original signal is because the “pushed” signal is nothing more than a mirror.

If you like your cable or satellite TV, great. I’ve never had satellite and cut the cord on cable in 2010 because the expense continued to climb.

I got the equipment I wanted on a one-time expense and it paid for itself in less than two years.