Reception, on the rebound?

Updated: May 14, 2021

Time to reflect.

"What are you talking about!" Let me explain...

Every TV aerial points in a particular direction - toward the TV tower it receives it's signal from. Just try to turn your aerial away from the direction of the tower and your pictures degrade to either nothing or something completely unwatchable.

It is also possible, in the rarest of cases, is to receive signal from a "bounce" (reflection, or multipath) either to the side or behind the signal from the tower.

This phenomenon occurs mainly in strong signal areas, geographically close to a TV tower, as the power of the signal from the tower hits nearby hills and bounces back to the aerial. Logically, this may cause issues with reception, but most new antennae today are designed to reject such signals coming from the back or side of the antenna, thereby ensuring a clean incoming signal from the front of the antennae.

This phenomenon also occurs in weaker signal areas too, though not as common due to the power of the incoming tower signal being much weaker, and therefore the reflected signal being further decreased.

Receiving a reflected signal may be advantageous for those who are unable to receive signal direct from a tower. It's often not recommended, unless it passes certain technical parameters and is thus deemed stable enough to provide around "99% uptime"' free of glitches and dropouts.

As a signal hits a hill and reflects it back (or to the side), it losses much of it's power and often much of it's quality, rendering it unworkable. However, it is still possible to receive a reflected signal that is both strong enough and hasn't lost any of it's integrity to make use of. It's in these situations reflected signals come into their own.

The pic above shows one such test installation. It's in Whakatane, where the path to the TV tower is shrouded by tall, thick trees and in an area where coverage is otherwise poor.

We tested from where a satellite dish had been installed previously, and found no usable signal (as stated) direct from the tower, but by rotating the aerial around 90 degrees from the tower, we picked up reasonable signal from a bounce off the hill. Signal levels for all 5 Freeview frequencies were generally well balanced, however they were not overly stable. With the addition of an extension mount, an amplifier and some serious fine tuning, we reckon we have things sitting around 90% uptime. Currently the pictures glitch (pixelate) occasionally, sound drops out every so often - a bit like rain-fade from a satellite dish - only in this case the disturbance lasts only a second or two at a time, and may happen around 4-5 times in an evening.

Just remember, reflective signal installations are the last tool in the toolbox we'll use to provide Freeview|HD reception. We'll always try first for signal direct from the tower and, failing that, only then look for bounces of an acceptable quality. Such installations are only be carried out on the understanding that glitches and dropouts are more likely to happen than not and there's nothing we can do to resolve them when/if they do.

But, for those who don't mind a small amount of irritation in return for pictures in HD quality, more channel variety and a chance to ditch the box, this solution just might be the ticket.

It's all part of thinking outside the square for solutions that have merit and ruling out those which don't. It's what we do here @ IntegriTech.

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