Bushcomm Horizon End Fed 3 BAND - 10M 20M 40M
12 metres physical length
Wire used: 1.6mm G304 grade stainless steel
Trap and balun winding: All copper
The antenna uses the grey balun box as it main fixing point. This can be a tower, pole, side of the house, tree etc. Stretch the main radiating element outwards and fix tight. As the wire is G304 stainless steel it can be pulled quite tight and will not stretch. This antenna is ground independent so earthing is not required.
When manufactured the antennas are hand tuned at approximately 3m (10 feet) above ground. For this reason when you install the antenna the height above ground or proximity of trees buildings sheds and so on will affect VSWR. You may have to retune for your requirements.
As stated in the product introduction, band width narrows with tighter VSWR requirements. As a commercial manufacturer we rated usable VSWR figures of under 2:1. The lower the desired VSWR the narrower the perceived band width will be. For example if 2:1 is acceptable you will have a usable band width of approximately 300 kHz. If nothing over 1.2:1 is acceptable then band width will be very narrow. In this case the addition of a tuner may be desirable to avoid constant retuning.
If you approach tuning with a practical understanding of the antenna and take your time you will find it quite easy.
It is vital that the longer wire between the
balun and the trap (10 / 20m) bands is adjusted first as this effects the 40m band adjustment.
To re tune the first section of wire from the balun use the clamp located before the trap.
Make the wire shorter to increase
frequency and longer to lower frequency.
If there is a variance between the 10 and 20m bands try changing the angle and
height of the antenna. Also be aware any metal, buildings or trees and so forth, near the antenna, will affect tuning. Clamp off the wire and make sure any loose wire is cable tided, taped or otherwise attached to the main radiating element.
To tune the 40m band you have to alter the length of the wire after the trap. If you want to go higher in frequency the wire needs to be shorter if you need to go lower in frequency then the wire needs to be longer. When desired centre point is reached once again clamp and tie off any loose wire.
Some general considerations.
* Use good quality UV stabilised rope or cord to secure the antenna. It will last longer and therefore is cheaper in the long term
* Generally speaking the best VSWR is easier to achieve when the antenna is installed at a ¼ wave in metres above the ground in reference to the target frequency. For example the 40m band antenna should be 10 metres above the ground, a 20m band antenna 5 metres above the ground. For this reason a multi or broadband antenna will always be a compromise. With this rule in mind, if your favourite band is 40m then try to install the antenna to favour this band.
* Why do we use stainless steel? We get asked this question a lot. In truth, copper is very slightly more efficient but the trade-off is a shorter life span. Copper corrodes and stretches. Stainless does not. So while this antenna is a moderate investment in price the materials used mean it will serve you well into the future.