Canadian TV, Computing and Home Theatre Forums banner

1 - 6 of 6 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1 (Edited)
I am using a yagi antenna plus booster to bring in a signal to my Ericsson W35 (Turbo Hub on Bell network) at my cottage. This is working with the current set-up - the signal is weak (zero bars on the W35) but stable and gives me goood voice quality and acceptable but variable data speeds.

What's odd is that the antenna gets best signal pointing opposite from the expected direction. I can't get a lock with the antenna pointing towards the tower. I'd like to understand why with a view to getting a better signal.

The closest tower in ENE for the cottage. The cottage is rectangular and the roof line is east-west. The antenna is on a pole on the east wall near the NE corner. I'd expect the yagi to get the best signal pointing ENE, but it gets the best signal pointing W of WSW (across the roof). The roof is metal and slopes northward. I also get a better signal when the antenna is lower - about equal to the peak of the roof

My guess is that the roof is acting as a big reflector. There is nothing W or SW that could bounce the signal like that, and there's a huge coverage hole west of my location, so there's no way I'm picking up another tower that way. What I don't understand is why the antenna can't get a lock when pointing towards the tower? If my roof can bounce enough signal back to the antenna, I'd think the antenna should be able to get a signal pointing to the source.

The roof is flat, but with ridges every 8 inches or so. It's also not aligned to reflect well - roof slopes N, tower is ENE, so I'd think the signal would bounce of to the NW. But the ridges could give a good angle back to the antenna - but they are narrow, so how much could they reflect?

Is it possible that the signal is weak on that corner (NE) of the building, but stronger as you move W? Should I try putting the antenna at the middle of the N wall - the roof is relecting something so try to get the antenna into the line the roof is catching?

I could try to get the antenna higher. The terrain would suggest that would be a good idea. But the roof is catching signal, or so it would appear.

I appreciate any helpful thoughts/suggestions.
 

·
Registered
Joined
·
8,336 Posts
The first question that pops to mind is what do you consider "pointing". With yagi antennas, the end with the shorter elements should point to the desired station. Some people are under the misunderstanding that the long elements face in the desired direction.

Yes, antenna placement can often have a significant effect, depending on reflections etc.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #3
OK, pointing means the short elements towards the source. The short elements are pointing the opposite direction.

The antenna is about as high as my roof peak. The roof is reflecting the signal to the antenna (I think). Can the roof (mostly below the antenna height) reflect a stronger signal that would be received pointing directly to the tower? That seems to be happening, even though the roof isn't aligned optimally for that.
 

·
Registered
Joined
·
103 Posts
I suspect with the antenna only at the height of the roof peak you could be subject to some reflected signals. Is there anything else around that might be reflecting a signal (like a hill or bluff even)? Or, you're actually picking up a different tower due to terrain obstructing line-of-sight to what is physically the closer one?
 

·
Registered
Joined
·
8 Posts
Discussion Starter #5
Yes, I'm thinking the roof (steel roofing) is reflecting the signal back to the antenna. There is nothing further in the direction the antenna is pointing that could reflect - I'm above the lake about 40 ft, and there is no higher ground for miles. Also, the antenna is pointing into a large coverage hole where there is no service for a long ways. It's like this:

Code:
Tower  --------- Ant-Roof -- Lake ---- big coverage hole
The antenna is pointing over the roof towards the lake. And I guess the roof is reflecting enough to make it work.

I'm going to try moving the antenna and see if I can get it higher. If the roof is catching enough signal to bounce back to the antenna, then there ought to be a spot the antenna can get a good signal on its own. True?
 

·
Registered
Joined
·
2,818 Posts
Yes, if the roof is metal and reflecting, you can try and take advantage of that property
Though, if it's reflecting it in a bad way (i.e. it's a ridged roof or something causing severe multipath), it may actually be better to block the reflections from the roof with a metal screen (think faraday cage)
 
1 - 6 of 6 Posts
Top