Receive signal from antenna's opposite direction? - AVS Forum
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post #1 of 7 Old 04-02-2013, 09:20 AM - Thread Starter
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In my location, most of my signals come from towers 30 miles away facing 214 degrees and 41 miles away facing 227 degrees. However, several signals come from towers 1 mile away facing 61 degrees.

If I use a ClearStream 2-V pointed at 214 degrees, will I be able to receive the signals from 61 degrees (basically almost "behind" the antenna)? I really don't want to install two antennas or get too pricey or too complicated, but maybe I'd have to. Is another antenna preferable?

I'm currently using a DIY 4x coat hanger bowtie / 2x4 setup now and get great reception except that the 61 degrees signals are a little on-again/off-again, I believe due to it's location on the roof. The house is completely blocking direct line-of-sight to the 61 degrees towers. I'd like to improve these signals and have it look a little less like coat hangers on a 2x4.

My apologies if I haven't explained well enough. I'm still learning.
Thanks for your advice.
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post #2 of 7 Old 04-02-2013, 10:27 AM
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When you have stations only 1 mile away, they're going to come in with extremely high signal levels no matter what you do, as they diffract and bounce back off of nearby houses, hills, street lights, whatever.

You should try taming the high signal levels by mounting the antenna so that there is some sort of signal blockage between it and the nearby towers, such as by your house or a metal "screen" of some sort.

You should also try REDUCING the signal level going into your tuner, either by inserting a spare 2-Way RF Splitter or a Variable RF Attenuator:
http://www.solidsignal.com/pview.asp?p=1296f&d=antennas-direct-20db-variable-attenuator-for-vhf-uhf-hd-off-air-reception-1296f&sku=853748001293
For every 1 dB of Loss, there is a 3 dB reduction in 3rd Order Intermodulation Distortion (IMD) Noise. Hence 3.5-4.5+ dB Loss in the RF Splitter will reduce IMD by about 10-15 dB. In your case, you might need 6-10 dB of added Loss.
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post #3 of 7 Old 04-02-2013, 10:39 AM
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You haven't given us much to work with. Do you need to receive VHF signals, and if so, from which direction? What are the channels you are having trouble receiving? We need your zip code, or better yet, your TVfool.com site analysis, to be able to better advise you.
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post #4 of 7 Old 04-02-2013, 10:15 PM - Thread Starter
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Sorry about not knowing what info you'd need. I hope this helps.

Zip Code 80530

I do need VHF channels which seem to come from 214-227 degrees.

The channels I'm occasionally having trouble with are 59.1, 59.3 and 59.4. Only 59.1 seems to be listed on the chart below. I assume that 59.3 and 59.4 come from the same tower. I'm watching 59.1 right now with no hiccups and about 70% signal strength according to my tuner box signal meter. Sometimes I get about 40% strength and it gets very jumpy or won't come in at all. It seems to be worse in rainy/foggy/windy weather, but I haven't completely narrowed down these criteria.

I have the DIY antenna on my garage roof now. There is no back on the antenna. The coat hanger bowties face 214 degrees which puts the back at 34 degrees. The tower with the 59.1 signal is at 61 degrees. Direct line of sight to 61 degrees is blocked by my house, but there are neighbor houses which may be bouncing the signal. I have nothing blocking direct line of sight at 214 degrees.

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post #5 of 7 Old 04-02-2013, 10:21 PM - Thread Starter
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Sorry about not knowing the info you'd need.
Zip code 80530
I have to get VHF channels coming from 214-227 degrees.
I occasionally have trouble with channel 59.1 coming from 61 degrees.
My DIY antenna is on the roof and faces 214 degrees with clear line of sight, but the back faces 34 degrees and is blocked by my house, so I'm thinking that this is the issue with receiving signals from 61 degrees. I have neighboring houses which may be bouncing the signal.
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post #6 of 7 Old 04-03-2013, 05:54 AM
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The station you are having trouble with, 59.X, really broadcasts on UHF channel 43. I wouldn't expect you to be having an intermodulation problem if you are not using a preamplifier, and even if you did have an intermodulation problem, it would be much more likely to disrupt your weaker signals whereas 59.X/43 is one of your three strongest.

Most likely, you are just experiencing an unfortuitous multipath bounce, where the direct signal path from 59.X/43 and the reflected signal are close enough to one another in strength to cause a cancellation problem. A different antenna can make things worse or better, but since they are already bad, any change in reception characteristics is more likely to help than hurt.

The Clearstream 2-V appears to have a VHF highband dipole, which is better at receiving network channels 7 and 9 from 30 miles away than your DIY bowtie, and it has a UHF reflector, which tends to reduce back signals while only slightly increasing gain. Does your DIY antenna have a reflector on it? You ordinarily benefit from a reflector, but in your case, the introduction of a reflector if you don't already have one would be a crap shoot, since it would be tending to further weaken the direct path signal component.

You might do better moving your antenna to another spot on the roof. Is that practical? If it is on a tripod, it is very easy to move it a few feet at a time and plot its reception quality and then plant it in the center of the best performance range, if you find a good one.
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post #7 of 7 Old 04-03-2013, 09:27 AM
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You need to block the high level signals from interfering ...

I like shiny stuff.
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