Vent Pipe Antenna Support For Small Antennas

By John--KL7JR

Here is a method of mounting a small HF/VHF/UHF antenna using your roof vent for support. This adds height for better perfomance of your antenna.

This idea was sent to us by John, KL7JR using a method he used from many years ago when operating on the 10 meter band using an Antron A-99 vertical.

It is really simple and requires few parts other than your antenna support mast.

John used 1 1/2 inch EMT for his mast, U-bolts and a length of wood.

In the drawing above, the board is U-bolted to the mast, then the entire mast with antenna installed on top is placed down inside the vent pipe. The board rests on top of the vent pipe.

Notes:

You must take care to not break the vent pipe especially if it is made from PVC. Note that during high winds, the wind force multplied by the antenna surface and the mast could break the vent pipe so you use this method at your own risk.

It is recommended that you do NOT use large Yagi type HF antennas with vent pipes as support for obvious reasons. Small wind load antennas are best used with this method of mounting. Remember that all of the weight of the antenna and mast rest on top of the vent pipe.

Using this method can work well with 6, 10 and 2/440 vertical antennas. 10 meter verticals should also work well but the wind load increases due to antenna lengths at 10 meters. If you use a small 2 meter Yagi, you will have to secure the mast directly to the vent pipe to keep it from turning in the wind.

Just remember that the vent pipes are usually made from PVC and not designed for mounting large heavy antennas.

Ground the antenna to a good earth ground rod. See another article on how to make a "stealth VHF/UHF" installation using much the same method as described in this article.

Don't forget roof climbing safety and don't install any antenna near power lines.....get help if needed.

Have fun!