The resistor absorbs part of the travelling energy and creates a travelling-wave behaviour.
Antennas · F1SYH
Flag antenna
The Flag is a resistively terminated rectangular receiving loop designed to provide a strong null in one direction.
HF
Réception
Cardioïde
Operating principle
Main characteristics
Typical gain
Faible
Impedance
Élevée
Polarization
Mixte
Difficulty
Intermédiaire
Dimensions and design
Horizontal length is generally greater than height. Exact geometry depends on band and available space.
Construction and tuning
Step 1
Build a rectangular loop.
Step 2
Install a resistor at one end.
Step 3
Place the transformer at the opposite end.
Step 4
Keep the loop away from metal.
Step 5
Determine the null through real measurements.
Advantages
- Pronounced directional null.
- Reasonable size.
- Broadband.
- Can be mounted vertically.
Limitations
- Low gain.
- Preamplifier often useful.
- Critical resistor and transformer.
- Not suitable for transmission.
History and origin
The Flag was developed as a compact receiving antenna in the same family as Pennant and EWE loops.
Safety
Disconnect or protect the system when transmitting on a nearby antenna.