G0KSC SC0604S 4el 50Mhz Yagi Antenna with a 2.402 Metre Length Boom

This is my smallest 50Mhz beam. It has a short length boom which is made from a single piece 1inch square tube section. No boom support will be required.

This antenna shows good performance and I have sacrificed a little front to back ratio in order to gain a little more forward gain.

As with all my antennas, this is a non-critical design and therefore, any small errors in you calculations when building the antenna WILL NOT have a great impact on the antennas final performance.

Dimensions in Metres

Element spacing:

• Ref =      0
• Driven =  .967
• D1 =       1.27
• D2 =       2.402

Element sizes per element half:

• Ref =       1.495
• Driven =   1.471
• D1 =        1.384
• D2 =        1.307

Performance figures @ 50.250Mhz:

• Froward Gain: 8.63dBi free space
• Front to Back: 19.22dB
• Radiation angle at 10 Metres above ground: 10 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.