Posted by
Charlie T, K3ICH on
Dec 08, 2018; 4:39am
URL: http://elecraft.85.s1.nabble.com/Flumoxed-tp7646765p7646942.html
I thought I said that.......
Oh wait I DID say that !
AND, A VEE will have a slightly more omni-directional pattern.
(That's where the gain of the horizontal dipole went !)
73, Charlie k3ICH
-----Original Message-----
From:
[hidden email] <
[hidden email]> On Behalf Of Bob McGraw K4TAX
Sent: Friday, December 07, 2018 9:18 PM
To:
[hidden email]
Subject: Re: [Elecraft] Less Than Perfect Antennas [was Flumoxed]
While I agree with Jim's information, I would point out the flat dipole will have 3 dB more signal off of its broadside 0/180° as compared to that of a inverted V dipole off of its broadside. At the same time, the inverted V dipole will have about 4.5 db more signal off of its ends 90/270° as compared to that of a flat dipole off of its ends.
It appears what one loses with one antenna is made up with the other antenna depending on azimuth and apex angle of the inverted V being somewhat greater than 90°. In fact it appears that the Inverted V has almost an omnidirectional pattern at an elevation angle of 25°. Fig 9.6
If a close match to 50 ohms is required, it is best to adjust the angle for lowest SWR while maintaining resonance by adjustment of the length.
Reference: ARRL Antenna Book, 22nd Edition, 9.1.3 Inverted-V Dipole
73
Bob, K4TAX
On 12/7/2018 6:51 PM, Jim Brown wrote:
> On 12/7/2018 12:55 PM, Dick Dickinson wrote:
>> Why is there so much promotion of dipole antennas over inverted vee
>> type antennas?
>
> As has been noted, an inverted vee is a compromise dipole -- the sort
> of thing you can rig with a single support. A flat dipole with its
> center at the same height as the inv vee will have a dB or two more
> gain, and the directional pattern will be the classic "figure-eight"
> pattern with broad peaks broadside to the wire and nulls off the ends.
> Inverted vees tend to lose the nulls off their ends. All this stuff is
> in the ARRL Handbook and Antenna Book which every ham should own and
> study as we have time.
>
> For rigging heights that are possible for most hams, horizontal
> antennas for 160 or 80, and 40M over flat terrain produce more gain at
> greater height. It is a fallacy that an antenna must be low to work
> short distances. Low antennas radiate LESS signal at high angles than
> high ones. I published a study of this several years ago. It's here.
>
http://k9yc.com/AntennaPlanning.pdf beginning on page 10. Field
> strength at 70 degrees vertical elevation just starts to fall off as
> it is raised to 1/3 wavelength. That's 45 ft on 40M, 90 ft on 80M, 180
> ft on 160M.
>
> 73, Jim K9YC
>
>
>
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