G0KSC Antennas
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G0KSC SC2805L 5el 28Mhz Yagi
OWA Yagis

G0KSC SC2805L 5el 28Mhz Yagi

Gain
10.78 dBi
F/B
18.48 dB
Elements
5
Specifications

Performance

Frequency
28–29 MHz
Gain
10.78 dBi
Front-to-back
18.48 dB
Elements
5
Dimensions

Element dimensions

Element dimensions (parsed from legacy body — check before publishing)

Element Position Note
Ref 0 mm parsed from legacy body — confirm position vs length
Driven 2116 mm parsed from legacy body — confirm position vs length
D1 3299 mm parsed from legacy body — confirm position vs length
D2 6004 mm parsed from legacy body — confirm position vs length
D3 8980 mm parsed from legacy body — confirm position vs length
Ref 2605 mm parsed from legacy body — confirm position vs length
Driven 2547 mm parsed from legacy body — confirm position vs length
D1 2419 mm parsed from legacy body — confirm position vs length
D2 2377 mm parsed from legacy body — confirm position vs length
D3 2308 mm parsed from legacy body — confirm position vs length
Modelled performance

Plots

About this design

G0KSC SC2805M 5el 28Mhz Yagi Antenna with a 9 Metre Length Boom

This is a good wide band long boom Yagi for 28 to 29Mhz with a real flat SWR curve that has been optimised for forward gain. It has a length boom of 8.98 metres and therefore needs to be made with a 2 piece boom of at least or 1,1/2 inch square. Boom support may be required.

Small errors in your measurements or calculations when building this antenna WILL NOT greatly affect performance due to it's non-critical design.

Dimensions in Metres

Element spacing:

  • Ref =      0

  • Driven = 2.116

  • D1 =      3.299

  • D2 =      6.004

  • D3 =      8.98

Element sizes per element half:

  • Ref =       2.605

  • Driven =  2.547

  • D1 =       2.419

  • D2 =       2.377

  • D3 =       2.308

Performance figures @ 28.500Mhz:

  • Froward Gain: 10.78dBi free space

  • Front to Back: 18.48dB

  • Radiation angle at 10 Metres above ground: 15 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 3inch or 3 inch boom as the elements sit high enough above the boom for the boom to have no influence.

If you are only able to obtain 1/2 inch elements in 6 metre lengths and can only obtain 5 metre lengths, join them in the middle at the insulator with a small piece of 3/8 inch tubing (600mm long) bolt the element to the insulator with 2 bolts either side of the boom.

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.