Antenna Directionality
 

Hello folks,

Now as I understand things, with a relatively short sloper antenna for
HF, the antenna will be pretty much omni-directional. At what length
does an antenna begin to have directional characteristics?

Thanks in advance for any help...

Junius

Antenna Directionality
 

In article . com,
"junius" wrote:

Hello folks,

Now as I understand things, with a relatively short sloper antenna for
HF, the antenna will be pretty much omni-directional. At what length
does an antenna begin to have directional characteristics?

Thanks in advance for any help...

It will happen at a high frequency. What frequency it happens at depends
on:

1. How long the wire is.
2. How high above ground it is.

--
Telamon
Ventura, California

Antenna Directionality - Question : At What Length Does An Antenna Begin To Have Directional Characteristics ?
 

Junius Asks - "At what length does an antenna
begin to have directional characteristics?"

Different Antennas have Different Directional Characteristics :
[ All other things being perfect and technically correct :]

1/4 WL Vertical Wire Antenna - Omni {Full Circle}

1/2 WL Dipole Wire Antenna - The Broad Sides

1 1/2 WL Long Wire Antenna - The Far End

Note - Since this is expressed in Wave Lengths (WL)
these are the General Directional Characteristics at that
Specific Frequency (WL) Only and at other Frequencies
up-or-down the Spectrum then the Propagation Pattern
of the Antenna may vary slightly or very radically.

OBTW - Lack of any Directional Characteristics can be
viewed as a Directional Characteristic of sorts - of course ! :o)

so now let the real facts and personal opinions begin . . .
as to what is what -and- what is not - iane ~ RHF

Antenna Directionality - Question : At What Length Does An Antenna Begin To Have Directional Characteristics ?
 

Be aware that although antennas exhibit directional characteristics - the
beam width at HF frequencies can be quite wide

Beam width is measured at th 3db points

A yagi might have a beamwidth of 30 to 60 degrees - but at the 3dB point an
s-meter on the other end might show only a half an s-unit decrease. There is
plenth of energy beyond the 3dB points.

Dipole beamwidths can be much as 130 degrees depending on height above
ground.

For some radiation patterns see
http://www.moonraker.com.au/techni/patterns2.htm

--
CL -- I doubt, therefore I might be !






"RHF" wrote in message
oups.com...
Junius Asks - "At what length does an antenna
begin to have directional characteristics?"

Different Antennas have Different Directional Characteristics :
[ All other things being perfect and technically correct :]

1/4 WL Vertical Wire Antenna - Omni {Full Circle}

1/2 WL Dipole Wire Antenna - The Broad Sides

1 1/2 WL Long Wire Antenna - The Far End

Note - Since this is expressed in Wave Lengths (WL)
these are the General Directional Characteristics at that
Specific Frequency (WL) Only and at other Frequencies
up-or-down the Spectrum then the Propagation Pattern
of the Antenna may vary slightly or very radically.

OBTW - Lack of any Directional Characteristics can be
viewed as a Directional Characteristic of sorts - of course ! :o)

so now let the real facts and personal opinions begin . . .
as to what is what -and- what is not - iane ~ RHF
.
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