Making a Magnetic LOOP-antenna with a Variabel VACUUM-Condenser 10.10.2012 UPDATED: 12-08-2013 minor
Gerlev, near Frederikssund, 12- 08-2013
|A MAG-LOOP is NO
competition to a full size dipole!
Is it an antenna ?,
Maybee, but only a if you have NO other option.
The loop was
placed at the point on the picture herunder, and the full size dipole
was elevated into 30 feed above GND.
I will NOT recommand this kind of antenna, if you in any way have the possibility to make a dipole, even a shorted dipole will perform better.
END of STORY
Planning a MAGNETIC LOOP-ANTENNA for use on 80, 60, 40 and 30 meter... ???
This page is my documentation on a project to make a MAG LOOP.
Reading all stuf on the
internet, to find the best solution...
This is a good place to start:
This page has a lot of Refferencis to other descriptions of small Magnetic Loop-antennas, and a lot of "how to..."
Consulted K8NDS, Richard
Fusinski about his phantastik project...
Richard has a some videos available on YOUTUBE - Access some of them from his QRZ.COM... Thanks for your input, Richard!!
Some tecnical reading about
Small Loop Antenna Efficiency in PDF.
First thing first... Get some material...
Picturen from 11.21.2012
The final MAG LOOP will be
Now, I still have some
I also have to figure out, how to the remote wire must go down to the shak.
In this setup it is
more easy to find the perfect match-point for the feeding-loop,
|The REMOTE-BOX in place.|
| A look from
The antenna is directed NORTH - SOUTH.
the point on my ruff, with a quart wave dipole for 30 m.. is in place.
My ruff is made of steel,
making a good ground for any kind of antenna, and I am realy
|A used Jennings Variabel VACUUM-Condenser:|
is: (copy from Jennings homepage)
Measured: MAX: 381 pF
Measured: MIN: 10 pF
Lenght: 217 m.m. without STUB for the shaft
Width: 75 m.m.
|Video: A MOTOR to drive a Vacuum-Condenser||2 minuttes of video shoving the KURSMOTOR running|
|4 minuttes of video shoving the finished remote steering and how it works.|
|A HAM-friend in spirit
have offered me this little engine from World War II.
Used in German figther-fly to correct the kurs.
This engine have a very
fine GEAR, using 24 Volt and 75 watt,
Now, must get it to fit.
|Was in STOCK in the
local HAM-club, for Dkr: 200,00 (40 US$).
Need a little cleaning before use.
Cleaning is DONE!!!
|The local HAM-club had
some picies of WAVE-GUIDE cabel.
I got 6 meter for free...
There was some grizy stuf between the isolation and the cobber.
Easy to remowe with Terpentine.
|Measured 16 m.m. X 26
This cabel is very light and still flexible and strong.
|As I expectet, this
cabel have possibility to hold the loop by it self.
Here just supported with some STRIPS...
I will have the
VACUUM-condenser mounted in the bottom, and make the the feed-point and
The bottom-mount of VACUUM-condenser will lower the weight-point, and make it possible to experiment.
Now... Have to do some motor-experiments...
Servo stearing of the LOOP-Antenna
Planning the Stearing:
|A = LOOP Connecting
B = LOOP Connecting point 2
C = Vacuum Condenser
D = PLEXIglass Wahl, 2 pcs.
E = 10-turn Potentiometer, for frequensreading scala on instrument
F = 1:2 Gearwheel
G = Insolatated driveaxel with m.m. gevind
H = Clutch
K = KURSMOTOR
L = Electric connetion Point
M = PLEXIglass mounting rod
The princip would be, that
when the K-motor is turning ON, one way or the other, and turn the rod of
VACUUM Condenser, a Gearwheel F:, 1:2 lower the 16 turn of Vaccum-Condenser to 8 turn on the E: 10 turn-Potentiometer, used to show a scala for relativ frequens, and to kipe an eye on where we are on the
The future plan will be, that a
PIC-processor will take care of logik, start and stop of K-motor,
Addition to this project would
be, to put a display on the control-box, READ the frequens, and auto-TUNE the
PIC-processor would be able to read tuning frequens, knowing last frequens, then
Always good to have a PLAN... We must se what the time will bring....
For the moment I am working on the LOOP-Connection point 1 and 2.
Her is the PLAN-SETUP.
Nothing is finished yet, but only the plan.
The board of plexi-glass is 42 cm long, and 10 cm width.
The gearwheel just fit...
enough room on the board...
Still to come -
Holder of the KURSMOTOR could bee like this:
Material: PLEXI-GLASS 14 m/m
|Now, the LOOP-RODS is
Just to get a pic. of kobber, with indside diameter of a half inc. 22 m.m. kost me
90 D.kr. ( 18 US$ ), to fit on the TOP
of Vacuum-Condenser, is a lot of money for
I hope it is worth it...
|A close-up foto of
Vacuum-Condenser with LOOP-connection rods.
In TOP of PAGE you will find a video of the finished remote steering af th vacuum-condenser.
No I just have to VATERPROFF the BOX before I make the LOOP-Antenna.
||The Control BOX
I used an old box from
another project, with a meter build in, and some hulls in the
The 500 Volt meter will
later be calibrated with frequens-bands. An inside resistor
Black NOP is a 1K
potentiometer to vary the voltage to the KURSMOTOR from app.
Right to the POT. is POWER-ON button.
In the bottom-left is
the cross-coubled switch for LEFT/RIGHT turning af the
Just now, I works with some ACRYL to pak the REMOTE in, for WX-protection.
This is the Balance-point, and the way it must be mounted on the mast.
FINISHED to day, 12.11.2012
NEXT THING will be to setup the LOOP....
This is my TEST-SETUP, just for a TRY....
Experimenting with the cublings-link
(this is NOT good...)
This is much
better, but not the best....
More pictures later... with more experiments...
REVERSE BEACON NETWORK
I can follow which station arround can hear my signal.
This i result of 100 watt to the antenna - FIRST TRY - Places 1 meter over ground in the garden.
The antenna is placed EAST - WEST.
SWR say 1.05 on my Italian EXPERT 1K-fa, but I think the antenna is to close to my window, only 3 meter away from the shack, so 300 watt is MAX effekt, on 80 meter until The antenna get his place on the ruff.
Today i got a glass-fiber rod.
Originally a commercial
antenna, 4 meter long, used for the band 450 - 460 MHz Mobil-band.
More to come...
More to come....