The sloping loop combines vertically and horizontally received components. Resistive termination creates a cardioid pattern with a pronounced null.
Antennas · F1SYH
K9AY loop
The K9AY is a compact resistively loaded receiving loop, usually switchable between several directions.
HF
Réception
Commutable
Operating principle
Main characteristics
Typical gain
Faible, rapport signal/bruit favorable
Impedance
Adaptation par transformateur
Polarization
Mixte
Difficulty
Avancée
Dimensions and design
The loop is electrically small on the lower bands. Exact dimensions are less critical than termination, transformer and surroundings.
Construction and tuning
Step 1
Install a central insulated support.
Step 2
Build two crossed sloping loops.
Step 3
Add terminating resistors.
Step 4
Build a receiving transformer.
Step 5
Install switching relays.
Step 6
Adjust values for the best front-to-back ratio.
Advantages
- Small footprint.
- Several switchable directions.
- Useful local-noise rejection.
- Wide lower-band coverage.
Limitations
- Relatively weak received signal.
- Ground-dependent adjustment.
- Requires switching and transformer.
- Less performance than a large Beverage.
History and origin
Gary Breed, K9AY, popularized the antenna as a compact directional receiving system for the lower bands.
Safety
Protect relays and transformers from moisture and induced surges.