Beam Issue

[wtp]

repeat, new coax ?

 

[spanky15805]

Pictures please.

 

[prcguy]

So after a bit of time, the antenna remounted, with correct mount and gamma match. Sadly, although slightly better, compared to an omni, just not much gain. So disappointed in it. Not worse than an omni, just not much better (10-15%). Thanks for all the suggestions, I appreciate it very much!

Did you check the SWR on the ground? You could mount it to 3ft of pipe and point it upwards to simulate how it will react on the roof mounted mast. I would check it with a short coax jumper and also with your full run of coax. If the antenna has good SWR on the ground and you can't get the coax down from the roof you can use the same short mast on the roof to test SWR with the long coax run before putting it back on the large mast.

 

[KF0NYL]

I did not see where the mast material was mentioned. Metal masts will interact with vertically polarized beam antennas.

I have an Arrow Antennas 2m beam antenna that I use for portable use and I always use a heavy duty fiberglass mast with it.

 

[W4AXW]

So after a bit of time, the antenna remounted, with correct mount and gamma match. Sadly, although slightly better, compared to an omni, just not much gain. So disappointed in it. Not worse than an omni, just not much better (10-15%). Thanks for all the suggestions, I appreciate it very much!

Not sure how you arrived at the only 10-15% gain number over a vertical omni, but any 5el Yagi should perform much better than that. As others have already speculated you may be seeing coupling with a metallic vertical mast.

 

[prcguy]

I did not see where the mast material was mentioned. Metal masts will interact with vertically polarized beam antennas.

I have an Arrow Antennas 2m beam antenna that I use for portable use and I always use a heavy duty fiberglass mast with it.

If you use an insulated mast with a center mounted beam and run the coax down the mast you will still have an interfering mast. It gets complicated trying to route the coax off the back side and around to avoid interference.

 

[KF0NYL]

If you use an insulated mast with a center mounted beam and run the coax down the mast you will still have an interfering mast. It gets complicated trying to route the coax off the back side and around to avoid interference.

This is true. I have seen most people run the coax to the end of the beam and into wide arc before attaching the coax to the mast below the antenna.

 

[skyview]

repeat, new coax ?

Yes the coax is new

 

[skyview]

Not sure how you arrived at the only 10-15% gain number over a vertical omni, but any 5el Yagi should perform much better than that. As others have already speculated you may be seeing coupling with a metallic vertical mast.

This is based on the stations received on the omni versus the vertical, of course not "scientific" but good estimation, and the difference is minimal. Im in Colorado and the topography in the direction Im pointed is relatively uniform (plains).

 

[skyview]

If you use an insulated mast with a center mounted beam and run the coax down the mast you will still have an interfering mast. It gets complicated trying to route the coax off the back side and around to avoid interference.

Well short metal mast, 4 ft, but omni on a metal mast too.

 

[wtp]

how far away is the tower/site you are trying to listen to ?