[Antennas] Questions on installed dipole

[George, W5YR]

Keep in mind that the antenna you described is not a symmetrical dipole.
One leg is 12 m long and the other is 16 m. Also the height is only 3 m.

This is an off-center fed dipole and it might show a small amount of
directivity, which may account  what you observe when you reverse the
feedline connections at the receiver. I have never heard of this effect
before, but that is the only reason that occurs to me.I do not know much
about your receiver, but I am surprised that it has a 300 ohm balanced
input antenna connection.

 Also, your antenna is so low that except at frequencies where the height
is the better part of a half=wavelength, the directivity effects should be
small at best.

Usually, the wire size has relatively little to do with the receive
performance on an antenna. Technically, larger wire has slightly more
bandwidth, but the effect is tiny in your case.

A lot of information on antennas is to be found in the ARRL Antenna Book if
you can get access to one.

Re trees, again their effect depends upon frequency. I have not found much
if any effect on the HF bands (3 to 30 MHz).

72/73/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771
Icom IC-756PRO #02121  Kachina #91900556  IC-765 #02437

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Zacharias Liangas wrote:
> 
> Dear friends of the list
> 
> MY question on a previous mesage has not been replied. Last week i have amde
> a temporory dipole antenna  with a wire of 0.5mm diametter  (telphonic wire)  the
> one part supported on trees  and the other supported over and by TV cables.
> The part over trees was 12 m but the other part was 16 m.Height is abt 3 m
> above ground.
> Connecting wire was  twin 1.5 mm  wire , conecte to the 300 OHm input of the
> ICOM RR75 ( has  digital S meter)
> Using it  i found that  reversing the wires in the 300Ohm  input  threre was soem
> little directivity , lower  signal (coresponding to the wire conected on the main) of
> up to 2 S units (or 12-15dB) even a antenna tuner is used!
> Making comparisons  with my main 16 m wire #12 signal is on most cases up to
> 2 S units less in my most wanted bands , but but with much lesser noise.( over
> 15 db)  height of this antenna is 5 m above ground.
> 
> MY questions are:
> It is corect that tress can effect reception?
> It is corect that reversing the poles of the dipole can seem as  using a  diferent
> antenna?
> It is also corect that  the low signal in receiver is due to very thin wire?
> 
> MY intention is later to install one 6 band inverted V.Maximum height will be abt
> 12m Do you have any ideas?
>