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A monster 18 element 144MHz Loop Feed Array Yagi

The LFA design has a patent pending and all G0KSC designs are copyright. Any ham can build for their own use or those of a friend. Where profit or commerical gain exists, express permission of G0KSC must be sought.

 

I wanted to present the first on-site model showing some serious advantages over traditional Yagis and this 18 element for 144MHz will not dissapoint. Providing over 18dBi forward gain and in excess of 32dB Front to Back and with no side lobes along with substancial unwanted forward lobe suppression.

To top of the antennas list of fantastic features, a completley flat SWR between 144MHz and 144.6MHz is also provided.

Built from Imperial sized material, our European friends will be disspointed. However, I will add a metric sized version too.

Below is both the Azimuth and Elevation patterns. Have you ever seen a pattern like this in an 18element Yagi?

 

The above diagram shows that this antenna is fed at the center piece of the frotn element with in the loop feed arrangement.

Construction:

All parasitics elements are made form solid 1/4 inch aluminium rod. The loop itself is made from 2 different sized tubing. The longest elements within the loop are made from 1/2 inch tube while the end pieces (with the bends) are made from 3/8 inch rod or tube and slide into the ends of the 1.2 inch tube. This allows for a trumbone effect for easy fine tuning of the antenna/loop system.

Go to the download page of this site Where you will be able to download the EZNEC design file for this antenna along with 4 bay stacking information too.

Specification:

Forward Gain  -             17.95dBi at 144.300MHz

Front to Back Ratio -      32.16dB at 144.300MHz

Peak Return loss -         -65.062dB at 144.250MHz

Boom Length -              12.987 Metres

Feed Loop Arrangement

The feed loop is made from larger diameter material than the parasitic elements. The largest sections on the loop are made from 12.7/13mm and the smaller sections from 9.6/10mm. All parasitics are made from 6.53/6mm solid aluminium rod. The picture below shows how:

 

 

 

 

 

 

 

 

In order to ensure the correct sizing and construction is undertaken, I have included the 4nec2 and EZNEC design files within the download area of this site. This will allow you to make alterations if you wish. However, I think this design is pretty much were it needs to be :)

Stacking and Baying information to be published soon.

Enjoy.

There is a patent pending on the LFA design. For Commercial use, contact G0KSC

 
 
 
 

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