Canvey Island, Essex, England Justin@g0ksc.co.uk
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Twin boom quad
144MHz LFA Yagis
144MHz LFA Yagis

Low Noise LFA Yagis designed by G0KSC free to build for personal use.

144MHz LFA Yagis
70cms LFA Yagis
70cms LFA Yagis
Twin-Boom G0KSC Quads
G0KSC Twin-Boom Quads
Twin-Boom G0KSC Quads
G0KSC Custom Dish feeds - Above installation @ HB9Q
Custom low-noise dish feeds
Custom low-noise dish feeds
G0KSC Custom Dish Feeds

Above installation @ HB9Q

G0KSC Custom Dish feeds - Above installation @ HB9Q
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G0KSC SC0609L 9el 50Mhz Yagi Antenna with a 12.2 Metre Length Boom

This antenna has been redesigned and represents what i believe to the the 'ideal boom length' for an OWA direct feed 50Ohm Yagi. This can be seen in the model in the super flat SWR, the high levels of F/B ratio along with the excellent gain and pattern.

The model below is designed with 12.7mm / 1/2 inch elements and also a 12mm version below . If you require a version of this antenna with another diameter wire, Email me and I will remodel. It is NOT POSSIBLE to simply resize the elements when using a VERY different diameter wire and get the best performance possible. Element positions also need to change for the ideal antenna to be achieved again. Please read all the way down this page, there are other versions of this antenna using tapered elements too. As I have more requests, I will remodel in other element diameters and tapers and publish those too.

Enjoy the antenna and if you build, Please Send me photos!

K7JA upgrades his 7el G0KSC OWA to a 9el G0KSC OWA (Centre of the cluster)

Dimensions in Metres with 1/2 inch elements

Element spacing:

  • Ref =      0
  • Driven =  .838
  • D1 =       1.012
  • D2 =       1.946
  • D3 =      3.588
  • D4 =      5.562
  • D5 =      7.750
  • D6 =      10.154
  • D7 =      12.234

Element sizes per element half:

  • Ref =       1.477
  • Driven =   1.461
  • D1 =        1.3915
  • D2 =        1.379
  • D3 =        1.346
  • D4 =        1.322
  • D5 =        1.302
  • D6 =        1.278
  • D7 =        1.272

Performance figures @ 50.150Mhz:

  • Froward Gain: 13.93dBi free space
  • Front to Back: 28.12dB

Dimensions in Metres with 12mm elements

Element spacing:

  • Ref =      0
  • Driven =  .838
  • D1 =       1.012
  • D2 =       1.946
  • D3 =      3.588
  • D4 =      5.562
  • D5 =      7.750
  • D6 =      10.154
  • D7 =      12.234

Element sizes per element half:

  • Ref =       1.4775
  • Driven =   1.4615
  • D1 =        1.392
  • D2 =        1.3795
  • D3 =        1.3465
  • D4 =        1.3225
  • D5 =        1.3025
  • D6 =        1.2785
  • D7 =        1.2725

Performance figures @ 50.150Mhz:

  • Froward Gain: 13.91dBi free space
  • Front to Back: 29.39dB

Azimuth Plot

Elevation Plot

This fantastic antenna at 20m up

An Excellent SWR to go with the fantastic pattern!

G0KSC SC14407L 7el 144Mhz Yagi Antenna with a 3.2 Metre Length Boom

This Yagi has been designed to cover 144Mhz to 145Mhz with an SWR figure less than 1.25 and at the same time exhibits a very good Front to Back ratio. It has a boom of 3.2 metres and therefore can be made from a single piece 1inch square tube section. No boom support will be required.

This antenna will not be affected be changes in weather or nearby antennas which can have an effect on lower impedance types. Also, small errors in your calculations or building the antenna WILL NOT greatly effect performance due to it's non-critical design.

The SC14407L Built by G4PDS

'Yes thanks, all is well. Have just completed a 7 element for 2 metres
(3.2 metre boom version) and have been testing it this afternoon.
Appears to be fine. Looked fine on the MFJ269 and when mounted on the
temporary mast in the garden there is nothing visible in the way of
reflected power, so I'm really pleased.
'

'Had it on the mast in the garden this afternoon, and among others
worked EB1LA in IN63VN (not sure what propogation mode, but may have
been tropo - 50W, IC-7000). So quite content with that - thanks !'

Ian G4PDS

 

Hi Justin,

I finished installation of my antennae. It's performing AMAZING, doing
great job. I am supriosed to see that the SWR is flat all way down the
band.

I used commercial anennas before but didn't act like this SWR wise.
Please find the photos of my setup attached to this email. My plan is
writing down all my experience on my BLOG (sorry but Turkish :
http://blog.barisdinc.net but you will find lots of photos of my
construction step there, hopefully tomorrow)

best 73's de TA7W
baris

ZL1RS made 4 of these for portable DXpedition work, the first was to the South Cook Islands. He also installed folded dipoles instead of a split dipole too.

 


 

Dimensions in Metres

Element spacing:

  • Ref =      0
  • Driven = .302
  • D1 =      .486
  • D2 =     1.02
  • D3 =     1.741
  • D4 =     2.547
  • D5 =     3.208

Element sizes per element half:

  • Ref =       .505
  • Driven =   .499
  • D1 =        .468
  • D2 =        .452
  • D3 =        .442
  • D4 =        .437
  • D5=         .435

Performance figures @ 144.300Mhz:

  • Froward Gain: 13.19dBi free space
  • Front to Back: 34.16dB
  • Radiation angle at 10 Metres above ground: 3 degrees

 

Element diameter:

Each element is made out of single piece 1/2 inch (12.7mm) aluminum tubing Each element half length needs to be doubled in order to gain your total element size. No difference is length needs to be calculated for the 1inch or 1,1/4 inch boom as the elements sit high enough above the boom for the boom to have no influence.

NOTE:

You can build this antenna with 13mm diameter tubing using the same parameters above. Slightly higher front to back ratio and forward gain will be seen along with a narrower SWR curve.

 

For construction information see 'G0KSC insulators' and the UKSMG article from the main menu on the home page.

 

 

 

 

 

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