A max. performance 40m - (60m) - 80m transmitting loop antenna.
Youtube video presentation : English version
201810 : Installing the new match box at the top (current maximum) of the 10m circumference loop. TuningC is at the bottom.
This is the ONLY good feeding point and best feeding system.
Resulting in a purely H-field radiating, BALANCED antenna and immediate good VSWR.
Wide band matching.
PCB available => PCB galery
New improved matching system.
G0CWT for his eye opening results from his empirical research.
K9YC for his much research on Common Mode Chokes.
DL4KCJ for his loop Q calculation formula.
- This low-Q, wide band, max. performance 10m circumference loop is developed after reading valuable experiences of G0CWT.
- The matching circuit is vastly improved by me, pa0nhc.
- This loop has its maximum efficiency (-0.5dB) at 40m, and only a little less at 80m.
- It has omni (non-directional) radiation characteristics.
- Installed at low height (1 to 3m) it is an NVIS (Near Vertical Indent Sky wave) antenna, optimal for regional QSOs (up to 300 km).
- Installed at 7-10m height above surroundings, it has DX possibilities at 40m and 80m.
- Perfectly and wideband matched at 40m and 80m, using a remotely switched ring core transformer.
- The matching circuit at the top of the loop is tested with 10 minutes 100W continues carrier.
- NO tuner is needed at 80m and 40m.
In a large ABS installation box at the bottom of the loop are the air tuning capacitor, a little 12V DC motor, and a simple to construct 1 : 13.500 mechanical reduction system.
A smaller ABS box at the top of the loop contains
the impedance matching system.
Both boxes are guarded against condensation by internal 5W heathers.
Properties of this loop :
- Small, only 2.5m square
- Omni-directional NVIS radiator for 40 - 60 - 80m.
- No radials nor ground needed.
- Installed at low height (loop center at 2.5m up) it radiates predominantly vertical (NVIS), optimal for regional traffic.
- If installed at 7m height => also useable for DX (see radiation patterns below)
- Transformer coupling compensated for leakage inductance => Immediately perfect wide band match on three bands.
- No ATU needed. JUST tune the loop for min. VSWR => ready for transmitting with perfect match.
- Closed, balanced system.
pure magnetic radiation
While receiving : Insensitive for E-filed man-made-noises
While transmitting : Minimal chances for BCI/TVI
with which the properties of small loops (circumference < 1/20 lambda) can be calculated.
Download "MMANA-GAL" for antenna modeling software.
patterns of my 10m circumference loop.
Calculated with "MMANA-GAL_basic" for specified loop center heights.
"Antenna height" is the height of the CENTER of the loop above "Ground".
(The loop bottom and tuning capacitor are 1.25m closer to the ground).
At low height NVIS properties on 80m band. NVIS and DX properties on 40m band when at elevated height.