Antennas

Quarter Wave -vs- 5/8ths Wave Vertical

q-wave-vs-5-8th-wave

Compare Red 5/8th -vs- Blue W/wave

Anyone who has mucked about with verticals will no doubt have worked out that a full-sized quarter-wave for the 40m band, more or less tunes up for 15m band.

It wasn’t until my entry in IOTA Contest this year that I convinced myself that they are not a cloudburner (as many people suggest) but compare favorably with a quarter-wave, even producing more gain by 2 dB at 10 degrees above the horizon.

OK, so 2 dB isn’t a huge gain, but hey – it’s free. Take it when you can!

Don’t forget, you can do the same for 10m band too by making an element 6.83m long and folding it back a further 1.11m (for 28.5 MHz). So you’ll need nearly 8m of wire. Don’t forget, that’s insulated wire!

4-Element Home-Brew Folded Dipole Yagi Dimensions

I’ve recently “made” a 4-element Yagi in software for my YouTube channel which should give a great match to 50 ohms.

If you’re into MMANA software modeling, here’s the file:

NOTE: This is a ZIP file because my Content Management System doesn’t like files ending in MMA. By all means have your Virus Scanner check this Zip file. There is only one file inside this ZIP. Just the MMANA file.

Quick SWR Calculator for Vertical and Dipole Ham Radio Antennas

Here’s a really simple way of double checking how to much to trim your antenna elements.

You only need to type in the numbers in the Cyan boxes.

Just type in where it is resonant right now – then type in where you would like it to be resonant and the spreadsheet will auto-calculate the trimming.

Film: How to use the SWR Adjustment calculator.