G0KSC SC0406M 6el 70Mhz  OWA Yagi Antenna with a 4.353 Metre Length Boom

This is a nice DX bean for 70Mhz. 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 of 1 inch or 1.25 inch box section aluminum.This should not need any support

Dimensions in Metres

Element spacing:

• Ref =       0
• Driven =  .411
• D1 =       .658
• D2 =       1.706
• D3 =       3.128
• D4 =       4.353

Element sizes per element half:

• Ref =       1.058
• Driven =   1.018
• D1 =        .977
• D2 =        .958
• D3 =        .942
• D4 =        .928

Performance figures @ 70.250Mhz:

• Froward Gain: 11.85dBi free space
• Front to Back: 26.31dB
• 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.

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!