[Elecraft] OT: Sloper Dipole Question

Wed Jun 18 12:31:00 2003

There is hardly an antenna so susceptible to influences by feedlines and surrounding conductive media, ground etc, as the venerable dipole and all it's variations.

For a sloper to have a decent pattern, either the feedline must be isolated from the wire AND pulled away from the wire at a right angle to the wire, OR the coax shield must be connected to the lower half of the dipole and the feedline can drop down at whatever angle. 

One can model this in EZNEC, etc with three separate wires, dipole upper, dipole lower, and a wire(s) following the path of the coax shield. All three connect to the center point. In EZNEC use an SI source on the lower end of the upper wire.

Mess around with the "shield" wire in the model. See what happens. 

If you hang this off a tower or next to other vertical conductors, the tower/whatever becomes part of the antenna, and MUST be added to the model to show what is going on. Slopers work better hung from trees. Harsh personal experience here. Ruined 40 meters for a sweepstakes that way.

73, Guy.

> 
> From: [email protected]
> Date: 2003/06/18 Wed AM 11:21:42 EDT
> To: [email protected]
> CC: [email protected],  [email protected]
> Subject: Re: [Elecraft] OT: Sloper Dipole Question
> 
> Vic, K2VCO wrote:
> 
> "Well, you would want the side with the highest current to be up.  I
> wouldn't be surprised if this turned out to depend on the length of the
> feedline.  Of course, you could use a balun and it wouldn't matter."
> ==========
> Why would it matter anyway?
> 
> 73, de Earl, K6SE
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