Antenna Orientation

[tripleplay905]

Hi, i have an scanner antenna mounted perpendicular to the side of my house. Sorta like this:

side of house
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| antenna
|=-------------------
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Since it is in a horizontal position would I get a fairly better signal by orienting it vertically about a foot away from the side of the house? Sorta like this:

side of house
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| |
| |
| |
| | antenna
|___|
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|

The antenna is presently mounted at about the middle of the second floor on the side of my house. Roughly 20 or so feet. Thanks for you advice.

 

[jrs71]

Generally you should keep your antenna polarized the same as the transmitting antenna you intend to listen to. Since most radio waves received by your scanner are vertically polarized, I would recommend having your antenna in a vertical configuration. Some examples of antennas that are horizontally polarized are TV, some amateur antennas, and some CB'ers run on the "flat side". Most public service and business antennas are vertically polarized.

 

[gcgrotz]

Cross-polarization can cost you dearly, especially at higher freqs. At 800 MHz it can cost you as much as 15-20db (-20db is 1/100 the signal strength) depending on what reflections you can pick up, also signals coming from the direction you are pointing (which would be the top of the antenna) will also be down by a bunch. You need to get that thing vertical!

 

[W4KRR]

Mount it vertically, assuming you're monitoring VHF/UHF/800 MHz frequencies, and if at all possible, mount it above the top of your roof.

 

[tripleplay905]

Thanks a bunch everybody who responded. I'm now looking at ways to mount it vertically.

 

[tripleplay905]

I have oriented the antenna vertically but I am now interested in yagi antennas. When I learn more info about them I am going to build my own. Can I connect 2 yagi's to one scanner via one coax line?

 

[k9rzz]

Can I connect 2 yagi's to one scanner via one coax line?

Short answer - no, but it depends upon what you're trying to do.

John K9RZZ

 

[tripleplay905]

Ok, i want to monitor a few cities to the west of me on 154mhz and some to the north of me on 424mhz. I've seen dual yagis before on one beem pointed in the same direction but I would need mine to point about 90 degrees from each other.

 

[zz0468]

Ok, i want to monitor a few cities to the west of me on 154mhz and some to the north of me on 424mhz. I've seen dual yagis before on one beem pointed in the same direction but I would need mine to point about 90 degrees from each other.

A yagi isn't what you need. A log-periodic antenna would be better for dual band operation. I suppose you could try a broadband power divider to combine the antennas, but you'd probably do as well with a decent omni directional antenna.

Another thing to consider... a directional antenna merely has more gain in a particular direction. That doesn't mean it's completely deaf in all others. A relatively low gain log-periodic aimed in the direction of the furthest or hardest to hear direction could hear the closer stuff just fine of the side or back.