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 SC0604S 4el 50Mhz Yagi Antenna with a 2.402 Metre Length Boom

This antenna has been redesigned and represents what i beleive 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 and also 12mm elements. 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 in my opinion, I remodel the whole antenna each time. 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 pulbish those too.

M1BTI built the SC0605S for QRP work

Dimensions in Metres - all tubing 1/2 inch / 13mm diameter, mail for other sizes and tapered elements

Element spacing:

  • Ref =      0
  • Driven =  .967
  • D1 =       1.270
  • D2 =       2.402

Element sizes per element half:

  • Ref =       1.495
  • Driven =   1.479
  • D1 =        1.385
  • D2 =        1.307

Performance figures @ 50.150Mhz:

  • Froward Gain: 8.54dBi free space
  • Front to Back: 18.83dB
  • 1:1.1 SWR B/W 600Khz

Dimensions in Metres - all tubing 12mm diameter, mail for other sizes and tapered elements

Element spacing:

  • Ref =      0
  • Driven =  .967
  • D1 =       1.270
  • D2 =       2.402

Element sizes per element half:

  • Ref =       1.496
  • Driven =   1.480
  • D1 =        1.386
  • D2 =        1.308

Performance figures @ 50.150Mhz:

  • Froward Gain: 8.53dBi free space
  • Front to Back: 18.93dB
  • 1:1.1 SWR B/W 600Khz

Azimuth Plot


Elevation Plot


This fantastic antenna at 10m up

An Excellent SWR to go with the fantastic pattern!

Remeber, mail me if you have different diameter tube requirements and send photos of built antenna!

G0KSC SC0407L 7el 70Mhz Long Boom OWA Yagi Antenna with a 6.63 Metre Length Boom

This is a nice DX bean for  70 Mhz. As always it has a nice flat swr curve and is built with in a non-critical format so any small errors you make whilst constructing will not have a huge impact on performance.

I recommend this to be built from a 5 metre length of 1.25inch box section with a 2 metre piece of 1inch box section slotted into and bolted to the director end of the boom to make up the additional 1.63 metres. The mounting point should still be in the centre of the 5 metre 1.25 inch section as the higher concentration of elements at the reflector end will counter balance the extended end of the antenna.

Dimensions in Metres

Element spacing:

  • Ref =       0
  • Driven =  .716
  • D1 =       1.082
  • D2 =       2.144
  • D3 =       3.655
  • D4 =       5.153
  • D5 =       6.63

Element sizes per element half:

  • Ref =       1.049
  • Driven =   1.022
  • D1 =        .974
  • D2 =        .942
  • D3 =        .93
  • D4 =        .917
  • D5 =        .837

Performance figures @ 70.250Mhz:

  • Froward Gain: 12.62dBi free space
  • Front to Back: 26.82dB
  • Radiation angle at 10 Metres above ground: 10 degrees

Element diameter:

Each element is made out of single piece 1/2 inch (12.7mm) aluminium 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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