How do I stop the howling / whistling caused by a 3m x 50mm galvanised pole with 3 x large grind aerials?
Background.
This thing is on the roof of my home.
When I first set the link up, I used a 38mm aluminium pole and a 24dBi 5GHz antenna with a 12dBi 2.4GHz omni. The hardware was a RB433AH with an R52 for the 2.4GHz and an R52H for the 5GHz. I was getting -70 from the 6.3km 5GHz link to my high site and was connecting neighbours up to 1km away with UBNT NS2 radios.
Everything was good.
Unfortunately things change. As more and more of my neighbours started wasting their money on ADSL (instead of buying wireless from us for less), more and more 2.4GHz APs started popping up. Within six months there was no longer a signal to the guys 1km from me due to all the noise.
But that didn’t matter as other people decided to start invading the 5GHz band and I was getting huge signal loss / dropouts on the high site. We upgraded the radio at the high site to an R5H. Things got better for a while, then there were problems again.
I eventually took the bull by the horns and replaced the 38mm pipe with a 50mm galvanised pipe that’s bolted to the wall with 4 lengths of threaded rod that go through the wall and are braced on the inside with spreader plates. The R52H at home was replaced with an R5H and the antennae both sides were replaced with 30dBi grids.
I then removed the omni, added an R52H to the RB433AH, replaced the R52 with another R52H and connected 2 x 24dBi grid antenna. They are staggered and are back to back. My clients can now connect again and the backbone is stable.
I know this goes against just about every rule of RF communications, but sometimes when you are surrounded by people who don’t want to play nice, you simply have to blast them out of the air. Result is that I can now connect people up to 5km away with UBNT NS2 and even further with MikroTik and 24dBi.
But now I have this howling noise on my roof that keeps all the people in my house awake during the night. This is a problem as Cape Town is famous for it’s “south easter” wind that starts blowing in September and only dies down in April
Any advice as to how I can damper or reduce the harmonics on this lot would be appreciated.
Ahaha well done!
Anyway.. did you try flat panels? They need a better mast against wind but they shouldn’t produce any noise by the wind passing through..
I’m using the Interline 23db 10° flat antennas for AP duty and the quality is pretty good. The beam is pretty large too!
Does the pole have open ends? I set up my first system with open-end poles, and it howled like a banshee! I stuck a PVC end cap (plumbing supply part) over the open end on the top, and the howling stopped.
I believe the noisy sound is from the 30dbi grid antenna…
And now you installed it back to back, OMG, there is no way to do with it…
exclude you install the flat panel antenna, one more thing is, 3m 50mm pole is not the good ideal, when the wind is strong, you got to worry whether it can take the load or not.
The “pipe organ effect” had never crossed my mind.
The galvanisers tend to make a mess of the ends of the pipes. Leaving runnoff and drilling holes to attach the wires to for when the pipes go into the tanks.
I’ll take some nylon and turn a pair of caps or plugs to close the ends up.
Strange you should mention pipe organ. That is exactly what mine sounded like. Off-key middle C.
Unbelievably LOUD!! Tape a plastic bag or the like over the top just to check.
I have never had any of my antennas whistle or howl. Some make kind of a buzzing noise in high wind, but barely audible over the wind.
