G0KSC SC42014W 14el 420-440Mhz OWA Yagi Antenna with a 1.843 Metre Length Boom
A Great Antenna for FM Dstar and Analogue Repeater working with no re-tuning required
This Yagi has been focused for maximum performance between 420Mhz and 440Mhz with an SWR of no more than 1.1. It gives excellent performance on the CW and SSB portions although the pattern is no so clean as a result of the ultra-wide bandwidth.
Remember, this is a very wide band Yagi although it only has 14 elements it provides good forward gain and excellent front to back. Performance of this antenna is very good with maximised radiation efficiency for direct 50 Ohm feed. For each 100 Watts input, at least 99Watts are radiated so this is idea for QRP (where very Watt counts) or QRO as the power limit for this antenna is your coax rating! Take a look at the images below.
Front to Back ratio has been tuned to allow you to still hear signals from behind although well down on the forward signal. This will ensure any rearward DX will be heard too!
The SC42014W above the SC14407L built by Baris TA7W
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
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
Minor errors in measurement during the construction of this antenna WILL NOT have a big impact on it's performance due to this antennas non critical design.
Dimensions in Metres
- Ref = 0
- Driven = .129
- D1 = .180
- D2 = .291
- D3 = .425
- D4 = .606
- D5 = .730
- D6= .869
- D7= 1.018
- D8= 1.167
- D9= 1.393
- D10= 1.58
- D11= 1.686
- D12= 1.843
Element sizes per element half:
- Ref = .168
- Driven = .165
- D1 = .146
- D2 = .140
- D3 = .1355
- D4 = .135
- D5 = .1275
- D6 = .129
- D7= .118
- D8= .1315
- D9= .1355
- D10= .131
- D11= .132
- D12= .1295
Performance figures @ 430Mhz:
- Froward Gain: 14.62dBi free space
- Front to Back: 26.8dB
- Radiation angle at 7 Metres above ground: 3 degrees
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.
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.