40m Hex Beam

November- 2005

The Project ’40m Hex beam’ was not my original idea. When I visited my friend Chuck W7MAP in Texas in September 2005, he showed me some designs of Hex Beams in the internet. I have heard about this antenna but haven’t had a closer look until then.¬†After coming back to Sri Lanka, I started to give a try on a hex beam for 40m since I already have good antennas for other bands.

Since I didn’t have a tall tower, I had to use whatever that is available. Therefore I decided to use the 30ft tower for the installation as you can see in the picture above.

The spreaders
It is not possible to buy fiberglass spreaders in Sri Lanka. Therefore I have used sectioned Aluminium tubes of 1/2″ joined by PVC tubes. The centre plate was made using a 1/4″ galvanized iron plate. It is drilled at 60 degree separation for the spreaders to get attached using two 5mm nut/bolt for each spreader. The centre of the plate is drilled and a 3/4″ GI pipe of 6″ is welded.

Feed Balun

I had a hy-gain 1:1 commercial balun to be used for the feed point. One can use a homebrew 1:1 balun for feeding. about 10 turns of RG6 cable bundled to prevent RF from leaking through the coax also will work if nothing is available. But a 1:1 balun is recommended.

The Dimensions
Rather than giving the dimensions only for the 40m version, I wanted to have the hex beam calculating spread sheet here. Please download and play around. This is a good tool to play around with and understand the different sizes for different bands.

On the air results

After installing the hex beam at 35ft, I was able to work few US stations on 40m using just 100W. This antenna performed about one S unit better than my inverted V and about 2 S units better than 160m vertical loaded on 40m. Definitely this 40m hex beam has a gain but the f/b was worse. When I rotated the antenna, I hardly see a difference. Many hams who have made hex beams gave me different thoughts but I want to add the DL7IO’s analysis of this antenna here. According to his analysis, the height was not enough for this antenna. Minimum height required would be about 60ft . Otherwise the takeoff angle is very high.

 

 

Free space without any losses. Ideal condition that never exists

30ft El pattern

30ft Az pattern

60ft El pattern