The more I read, the more confused I get. One minute it is currents and such and a minute later it is voltage and such.
Well Eddie, it depends on how & where you feed it, and if it's length to the tip is a multiple of a 1/4 or of a 1/2 wave, or...
When you feed at a current node you tend to have close to a 50Ω feed point impedance, a voltage node is closer to 1KΩ to
infinite impedance.
What Bob85 & The DB are referring to, here, is feeding the full-wave dipole (2 x 1/2 wave) at the minimal current, maximum voltage node where the impedance will be extremely high...
- Now, I KNOW you already know this so what, exactly, are you scratching your heed over?
BTW, it's the Current which does the work, and what we look for, to project which polarization the antenna will be.
For example; Feed a Quad installed in the
square shape, at the center of the bottom and you'll have an horizontally polarized radiation pattern because the current peak is found at the feed point,
... going toward
minimum current and maximum
voltage 90° away, at the center of the upward (vertical) sides of the square, because the current & voltage are 90° out of phase.
Eddie, This is partly why I'm having a hard time with the dual 1/2 wave "
in-phase" dipole design we've been discussing here, because feeding it (either with coax or balanced line) - it will want to bring the high
current node to the center feed point, especially if using a tuner, because that's where it finds the most friendly impedance,
- but that will then show a pattern like
this model! (which also shows a little of the equal but opposite currents on the balanced feed line, as it meets the antenna elements).
What the 2 x 1/2 wave dipole needs in order to present two "centered-peak" current nodes (or bubbles) - 1 per side - is a forced VOLTAGE-FEED which is extremely high impedance at the feed point, as you know from your 1/2 wave monopole models.
My contention is that the two sides won't be in-phase but will each show a 180° difference in potential to a neutral ground, and directly broadside to this dipole they will cancel one another,
- but at an obtuse angle, (say 45° from directly broadside) it should provide about a 6dB-
down cloverleaf shape - where the receiving station will be seeing the closer element about 90° earlier or sooner than the further element, allowing about 1/4 power to radiate in that direction.
In my mind's eye, if a 1/2 wave U-turn of wire, (like a 1/4 wave of hanging balanced line which was shorted across at it's bottom end and blowing in the breeze) were added at the voltage-feeded point of the 2 x 1/2 wave dipole, but on ONE SIDE only, then that first 1/2 wave of out-of-phase energy on
that side only would go down the balanced line 1/4 wave and back up 1/4 wave (1/2 wave total) - creating a null condition for that out-of-phase 1/2 wave of current and re-phasing back IN-phase that side of the 2 x 1/2 wave dipole, only half of which is connected to the
other side of the top of that piece of shorted balanced line - creating a condition so now the two sides of the 2 x 1/2 wave dipole would both be in the same phase.
...I probably could've written that better
- But there ya go, I laid a pretty big egg, anyone wanna try to boil it?
