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Old April 18th 06, 10:00 AM posted to rec.radio.shortwave
RHF
 
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Default Why Tilt ? - The Terminated Tilted Folded Dipole (TTFD / T2FD) Antenna

Raśl,

Why Tilt ? - The Terminated Tilted Folded Dipole (TTFD / T2FD) Antenna
http://groups.yahoo.com/group/Shortw...a/message/9085

Terminated Tilted Folded Dipole (TTFD / T2FD) Antenna
http://en.wikipedia.org/wiki/T2FD
http://www.electronics-tutorials.com...nna-basics.htm
http://www.hard-core-dx.com/nordicdx...wire/t2fd.html
http://www.hard-core-dx.com/nordicdx.../t2design.html
http://www.hard-core-dx.com/nordicdx.../t2fdfeed.html
http://www.hard-core-dx.com/nordicdx.../t2fdcomp.html
http://www.hard-core-dx.com/nordicdx...re/t2fd_1.html
http://www.radiohc.org/Distributions/Dxers/ttfd2.html

An Antenna that incorporates these Four Design Elements
to achieve Broad Banded performance :
1. Terminated
2. Tilted
3. Folded
4. Dipole Antenna
http://www.cebik.com/wire/t2fd.html


Starting with #4 the Basic DIPOLE ANTENNA.
http://www.radio-electronics.com/inf...ole/dipole.php
http://www.ycars.org/EFRA/Module%20C/AntDip.htm
The Dipole is generally a Half-Wave Antenna 'cut' for
one Specific Frequency; Mounted at a Set Height for
that Frequency and Positioned for a general Off-the-Sides Broadcasting
and Receiving. Usually the Dipole is mounted
Flat some times in an Inverted "V" or Sloping and even
Vertical.
http://en.wikipedia.org/wiki/Dipole_antenna
How High should my Dipole be ?
http://www.qsl.net/aa3rl/ant2.html
FWIW - The Radiation Resistance of a properly installed
Half-Wave Dipole Antenna is 75 Ohms.


The FOLDED Dipole #3 is simply a Dipole that is Folded
Back Over on Itself making it Double. If one Dipole is
a Half-Wave Antenna then it follows that a Double Dipole
is a Half-Wave Antenna Times-Two = a Full-Wave Antenna.
The Folded {Full-Wave} Dipole generally has better Band
Width then the Half-Wave Dipole Antenna. Most often the
Fold Dipole is mounted Flat and sometimes Vertical. The
directional characteristics of the Folded Dipole Antenna
again are Off-the-Sides for Broadcasting and Receiving.
FWIW - The Radiation Resistance of a properly installed
Folded {Full-Wave} Dipole Antenna is 300 Ohms.
http://www.radio-electronics.com/inf...ded_dipole.php
http://www.qsl.net/w4sat/fdipole.htm
http://www.arcticpeak.com/antennapag...ded_dipole.htm
TV type Folded Dipole Antenna
http://www.wfu.edu/~matthews/misc/dipole.html


TILTED #2 is used to get the T2FD Antenna off the Horizontal
where much of the signal is Off-the-Sides and give the
Wire Antenna Elements a little Vertical Dimension to make
the Antenna Radiate all around equally in all directions.
Tilting also varies the Height-above-Ground of the Antenna
and thus the relationship of the Wire Antenna Elements to
the Ground has no one specific frequency as in the Basic
Dipole Antenna. {Ground Reactance ?)

RAUL - SO TO ANSWER YOUR QUESTION
Titlting helps to make the T2FD Antenna Omni-Directional.


TERMINATED #1 is used to match the impedance characteristics
of the Folded Dipole Antenna over a much broader Frequency
range then the un-terminated Folded Dipole.


TWO SHORTWAVE LISTENER (SWL) T2FD ANTENNAS :
NOTE - For the Shortwave Listener this T2FD or TTFD
Terminated Tilted Folded Dipole (T2FD) Antenna design
seems to be preferred. It uses a 4:1 Matching Transformer
(Balun) and a 75 Ohm Coax Cable feed-in-line with a
390 Ohm Terminating Resistor.
http://www.hard-core-dx.com/nordicdx.../t2design.html
Or this Terminated Tilted Folded Dipole Shortwave Listener's
(SWL) Antenna that uses a 10:1 Balun with a 50 Ohm Coax Cable
feed-in-line with a 470 Ohm Terminating Resistor.
T2FD = http://www.johncon.com/john/T2fd/


GROUNDING of the Terminated Tilted Folded Dipole (T2FD)
Antenna is not required since it is a form of a Dipole
Antenna an in an of itself does not require a Ground to
make it a fully functioning Antenna. However your Radio
Shack should have a good earthen Ground Connection and
through your Radio Shacks equipment the T2FD will have
a Ground Path of sorts. To that end ensure that you have
a good earthen Ground Connection for your Radio Shack that
is Bonded to your House's Electrical System.


hope this helps - iane ~ RHF
.
.
.. .
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Old April 18th 06, 01:43 PM posted to rec.radio.shortwave
Dale Parfitt
 
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Default Why Tilt ? - The Terminated Tilted Folded Dipole (TTFD / T2FD) Antenna


"Han" wrote in message
ups.com...
Hello

As far as I know , you have to tilt the antenna to get the right
reveiving curve/ angle. for distant stations it is good to receive low
incoming signals . By tilting this is achieved.

I use a 17 meter long T2FD for over 10 years and it is a antenna which
not gives a high signal level but a clean signal!

I see this as an advantage

Greetings Han, the netherlands


Tilting the antenna (assuming the average height remains the same) does not
alter the takeoff angle (or elevation of the main lobe).
Download the demo version of EZNEC and you can see this for yourself.
The elevation angle is purely a function of height above ground of the
current loop(s).
Dale W4OP


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Old April 18th 06, 10:21 PM posted to rec.radio.shortwave
RHF
 
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Default Horizontal, Vertical and Sloping Dipole Antennas [Was : Why Tilt ? - The Terminated Tilted Folded Dipole (TTFD / T2FD) Antenna]

Dale [W4OP],

Horizontal, Vertical and Sloping Dipole Antennas
http://groups.yahoo.com/group/Shortw...a/message/9090


HORIZONTAL DIPOLE ANTENNA :
A basic Horizontal 1/2 WL Dipole Antenna that is Flat
with the Center mounted at 1/4 WL above-the-ground
and existing in a plane parallel to the ground; can be
said to Radiate mostly Off-the-Sides and not the ends.
This Horizontal Dipole Antenna has a predictable
Take-Off-Angle.

- - - The Surface of the Ground acts as a Reflector causing
the majority of the Signal to go Up and Off-the-Sides of
the Wire Antenna Element in a Horizontal plane : Making
the Horizontal Dipole Antenna mostly a Upwardly Radiating
Bi-Directional Antenna.


VERTICAL DIPOLE ANTENNA :
Conversely a basic Vertical 1/2 WL Dipole Antenna that
is Straight-Up-and-Down with the Center mounted at 1/4
WL above-the-ground and existing in a plane perpendicular
to the ground; can be said to Radiate Equally-All-Around;
but not off the ends. Again this Vertical Dipole Antenna
has a predictable Take-Off-Angle.

- - - Again the Surface of the Ground acts as a Reflector
and the majority of the Signal to go Up and Equally Around
(Still Off-the-Sides) the Wire Antenna Element in a
Horizontal plane : Making the Vertical Dipole Antenna an
Upwardly and Outwardly Radiating Omni-Directional Antenna.


30 DEGREE SLOPING {SLANTED} DIPOLE ANTENNA :
So we come to a 30 Degree Sloping Dipole Antenna that
is Slanted at an Angle Off-the-Horizontal {Vertical?} with
the Center mounted at 1/4 WL above-the-ground. Here the
majority of the Signal can be said to Radiate Off-the-Sides
but a portion of the Signal will Radiate Equally-All-Around;
but still not off the ends. As you point-out the Take-Off-Angle
would be closer to the Horizontal [Flat] Dipole Antenna.

NOTE - The lower Tip of this Slanted Dipole Antenna is
3/16 WL above the ground and the upper Tip is 5/16 WL
above-the-ground and the Vertical Dimension of the 30
Degree Sloping Dipole Antenna is 1/8 WL which makes
it effectively a 1/8 WL Vertical Radiator.

- - - Again the Surface of the Ground acts as a Reflector
and the majority of the Signal will go Up and Off-the-Sides
of the Wire Antenna Element in a Horizontal plane; however
some of the Signal does radiate in-all-directions in the
Horizontal plane : Making the 30 Degree Sloping {Slanted}
Dipole Antenna less of a bi-directional Antenna and more
of an omni-directional {semi-omni} Antenna.

Well that is the way that I 'envision' the Radiation properties
of the 30 Degree Sloping Dipole Antenna in my-minds-eye 8;-}

T2FD / TTFD ANTENNA :
Back to Why "Tilt" the Terminated Tilted Folded Dipole (TTFD /
T2FD) Antennas - - - The above rational is my simple understanding
of One-of-the-Whys for the 'tilting' of the Terminated Tilted Folded
Dipole (TTFD / T2FD) Antennas. To help slightly improve the
Omni-Directional characteristics of the basic Dipole Antenna in
this more Broad Banded design and application.

Oops ! - IIRC - FWIW - I am frequently right . . .
except when I am wrong, Wrong. WRONG !
{ Please Educate and Enlighten Me - Should I Be :-}


very little science coupled with mostly common sense - iane ~ RHF
[ Keeping It Simple ad Practical = KISAP :]
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