[Antennas] ANTENNA EXPERIMENT ,
Zacharias Liangas
[email protected]
Tue, 15 Jan 2002 12:26:09 +0200
Please submit your replies directly to me
ANTENNA EXPERIMENT
ON Saturday 12-1`and Sunday 13-1 I have made a temporary experimental
dipole antenna with active elements of 12 m and 16 m. Wire used is 0.5m si=
ngle
copper wire
Receiver connection [say here twin wire ] cable was a twin , stranded copp=
er wire
, of 0.15 mm each wire, length is about 6 m.
Dipole has been constructed having the same lengths for both parts however=
due to constraints of the garden a small part of the antenna has been fold=
ed
As the system is only temporary , I have supported this antenna into natur=
al
supports. Left part ( the 16 m is suppored by another wire of same type , =
about 3
m and this over two antenna TV cables in order to be a little high.( abt 3=
m from
the ground) This connected to the balckpart of the twin wire
The other part is supported by 3 tress on nearly the same height but about=
3.5 m
of length has been wound due to constraints of the garden.This connected t=
o the
red part of the twin wire
This is the first experiment . Later this year i intend to install a m=
ultiband
inverted V ( 5 dipoles connected tp a main) over the roof for a maximum l=
ength
of 20 m per pole ( fixed installation)
Two series of tests have been made :
Comparative dipole cs 16 m wire testing
Same testing but MFJ antenna tuner 16010 has been used
Results as opinion form:
Mysteriously when reversing the �poles' on the radio R75 � is like using =
two
diferent antennas , even when using the antenna tuner. Different signal le=
vels
and different noise levels and sometimes directivity It seems that ground=
does
not play its role correctly (?)
Possbly due to very thin wire , most signal levels are lower than single w=
ire
antenna. I am correct? If thiis is true this diference can be 6 db lower d=
ur to
surface only.
At several bands though signal levels are lower than single wire antenna i=
n most
cases have lower noise levels . As in example 7120 IRRS at 0915 shown leve=
ls
below S1 unit - still with the antenna tuner - but was noise free . IN con=
trast to it
the single wire antenna shown levels of S3 full of noise ( no signal was a=
udible)
IN another example R cochiguaz 2120 on Sat 13 was audble ( still as margin=
al)
only with the dipole
Dipole has enhanced reception in my most un-useful bands: LRA Argentina
feeeder at 29810 has 3 S units higher level than single wire More particul=
arly:
29-25 , 14-13, 11-10 , 4-3, 1.6 Mhz shown enhanced reception=A0
IN the highest bands both a capacitance and inductance are required to tun=
e the
dipole . IN the lower bands ( from abt 7 Mhz and lower) only inductance is=
required . On 9 MHz different antenna tunings are required between the sin=
gle
wire and dipole
Here are the measurements:
Legend:
AB black red ( connected to input / ground correspondingly)
BA red black
Red: pole from the tree side
Black: the free to air wire
IN all these cases cables are connected to the 300 Ohm input
Measurements without antenna tuner
180 5 5 5
245 3.5 3 4.5
1448 7 3 5.5
1456 7.5 6 7
3870 9 7
3890 7.5 7 5
3945 7.5 7 3.5
4060 9 clr 7 5 QRN
5050 3.5 5.5 9
6060 0 0 7
6085 3 1.5 9
6460 4 9
7105 9 5 7
7120 0 0 4 only QRN
7160 3 2 6 much QRN
7250 +10
7265 4 3 5
7560 3.5 3 7
9320 4 4 7
11585 8 8 8
12015 6 5 2
14020 9 9 7
15172 9 AB 9 noise BA 9+10 16m
15630 5 QRN 7.75 clr 7
15685 2 AB 2BA 5
17548 7 5 5
21455 6 6.5
21660 7 5-7 3
measurements with antenna tuner MFJ 16010
268 4 3 4
747 8 9! 7
1600 9.5 9 8
5161 tty 8 4 5
5796 6 4 7
6060 2 5 full QRN
6165 5 6
7120 3@+10 3
7265 5 7
9515 7 7.5
11300 4 5 -
15000 5 4 6
15310 5 4 6
17335 7 5 6
21465 8.5 5.5
21845 8 5
25740 9 5
25740 9 10
___________________________________________
pen-DX sejak 72 - anggota World-DX-Club 2104,Play DX, dll
PP: R75/HF150/MVT7100/D2935 + 16m/1x1 +
MFJ16010/1040/1025/752c/462
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