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Real World Vertical Bandwidth

All I can suggest playing with to increase bandwidth is to increase the diameter of the radiator. Try making one with 1 to 2" diameter pipe and see what happens.
 
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That's why I'm asking the question. I want to know what the benchmark is. 4 MHz 2:1 bandwidth at, say, 28 MHz is about 14%. But if that same technique is applied to, say 3.725 MHz, then that's 520 KHz... and THAT is enough to cover the entire 80M band!
73

Bill KT4YE

Bill, 1/4 wl vert on 75 meters broad-banded to cover the entire allocated frequency is easy enough.

Use less radials, an imperfect ground plane will increase the feed point impedance to 50 ohms and thus give a wider use able band width.

Try using one ground radial, you will get your 4 mhz bandwidth maybe.
Then add four more radials and test the band width. Every time just keep adding four more radials until you get to a 1.5:1 or 35 ohm impedance. Should be somewhere around 24 to 32 radials for this depending on your soil conditions.

The better the ground plane the more efficient the vertical is. The poorer the ground plane the less efficient it is. But it will be broad banded.

Just like reading how some of the ops pound a 8' ground rod in the ground and attach there coax shield to it then run a wire vertical attached to the center of the coax, trim it for best VSWR and WOW it is so broad-banded.

Like I mentioned before, can not change the laws of physics. Magicians try to, but that is just an illusion.
 

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