When I was younger I noticed that most yagis had approximately equal spacing between the elements.
More recently I've noted very different spacing patterns. For example the outer directors were very widely spaced while the first director was not far from the driven element.
And when I was experimenting with a 4 element beam for 2m directly fed with 50 ohm coax I found I could get a match with wide bandwidth with this narrow driven element/first director spacing. On 144 MHz this spacing is about 10cm or 0.05 wavelength.
Only recently did I find that these types of yagis had their own name - Optimised Wideband Array or OWA for short.
They are easy to feed and have a good bandwidth. The main compromise is you lose a small amount of forward gain.
Anyway here's some OWA links you might find handy for your next antenna project.
PS: Are you interested in more portable antennas? If so this book could be just what you need. Available as an ebook or in paperback you can find out more here.
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