DUAL-YAGI
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How are you combining the two antennas to the feedline?
If you take two identical Yagi's, which you have, and point them in the exact same direction and have them at the proper spacing apart you can get up to 3dB more gain and a narrower pattern. That means if your antenna is rated at 6dB gain you can get up to 9dB when they are properly spaced and combined. This also implies you have a proper 50 ohm divider or phasing harness to combine the antennas. This only works when you have the dipole feedpoints on both Yagi's in phase but in this case you don't as one is pointing up and the other down.
When you combine two identical Yagi's like you have, pointing complete opposite directions, which you did, you will incur about 3dB of loss on each antenna. That means if your antennas are each rated at 6dB gain each, they are now about 3dB gain each.
This loss is due to the divider loss which is 3dB and you are not pointing the antennas in the same direction and adding their gain, which would be a 6dB improvement minus the 3dB divider loss leaving you with a net 3dB gain for antennas pointing in the same direction. But their not pointing in the same direction. If you used a T adapter count on more than 3dB loss.
In my opinion you would be better off with a single omni directional antenna with 3 or 4dB gain.
If you take two identical Yagi's, which you have, and point them in the exact same direction and have them at the proper spacing apart you can get up to 3dB more gain and a narrower pattern. That means if your antenna is rated at 6dB gain you can get up to 9dB when they are properly spaced and combined. This also implies you have a proper 50 ohm divider or phasing harness to combine the antennas. This only works when you have the dipole feedpoints on both Yagi's in phase but in this case you don't as one is pointing up and the other down.
When you combine two identical Yagi's like you have, pointing complete opposite directions, which you did, you will incur about 3dB of loss on each antenna. That means if your antennas are each rated at 6dB gain each, they are now about 3dB gain each.
This loss is due to the divider loss which is 3dB and you are not pointing the antennas in the same direction and adding their gain, which would be a 6dB improvement minus the 3dB divider loss leaving you with a net 3dB gain for antennas pointing in the same direction. But their not pointing in the same direction. If you used a T adapter count on more than 3dB loss.
In my opinion you would be better off with a single omni directional antenna with 3 or 4dB gain.
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belvdr
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I believe that to be the case. Notice where the two feedlines meet between the antennas. I think that's a T and the feedline from the radio comes up inside the PVC.
Not sure exactly what I'm looking at in that little 320x240 thumbnail image. Plus, not having any idea of what the OP wants to accomplish makes it kind of difficult to determine whether it will work or not.. But.. As prcguy points out.. A pair of Yagis can be connected together using a proper divider.
Back in the golden days of amateur packet radio, we had a wide area 2 meter network. The regional 2 meter nodes were interconnected through a 70cm backbone. There was a 90 mile UHF hop over the flat prarie that was somewhat marginal. So, we put a relay station midway. We used a pair of Yagis back to back connected through a power divider. It was mounted on on a 50 foot tower. Worked great with a 40W radio..
Back in the golden days of amateur packet radio, we had a wide area 2 meter network. The regional 2 meter nodes were interconnected through a 70cm backbone. There was a 90 mile UHF hop over the flat prarie that was somewhat marginal. So, we put a relay station midway. We used a pair of Yagis back to back connected through a power divider. It was mounted on on a 50 foot tower. Worked great with a 40W radio..
The construction looks OK.. (A larger image would have helped).. I've done the 'Yagi out the window' thing. I once put an 11 element Cushcraft 440 Yagi together sitting in my living room.
For fun I mounted it on a camera tripod and pointed it out a main floor window that faces a repeater over 30 miles away. I connected it to a 5W handheld. I managed to get in pretty solid. Couldn't do it at all with the handheld's rubber duck antenna.
Why do you have two Yagis pointed in different directions? Pointing them in the same direction will give you 3dB gain (providing they're spaced and fed properly).
For fun I mounted it on a camera tripod and pointed it out a main floor window that faces a repeater over 30 miles away. I connected it to a 5W handheld. I managed to get in pretty solid. Couldn't do it at all with the handheld's rubber duck antenna.
Why do you have two Yagis pointed in different directions? Pointing them in the same direction will give you 3dB gain (providing they're spaced and fed properly).
cause the repeater is 330 NW and my simplex guy is 110 SE.
im sure it could be optimized. thanks for the input.
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