FPV drones have become the primary threat on the front line, and with that, the requirements for EW system antennas have changed. The decisive factor is radiation geometry — that is, how exactly the antenna “covers” the space around a position. That is why the quadrifilar helix antenna (QHA) has transformed from a niche solution into one of the core elements of dome EW systems.
What a Quadrifilar Antenna Is
A quadrifilar helix antenna consists of four helically wound conductors positioned at angles to one another. This design produces circular polarization of the signal — unlike the linear polarization to which most whip and cloverleaf antennas are limited.
A circularly polarized signal reaches the target equally well regardless of how the target is oriented in space or from which direction it is approaching. For countering an FPV drone that is maneuvering, changing altitude, and varying its attack angle, this matters: a linear antenna in such a situation loses effectiveness precisely at moments of sharp changes in the target’s trajectory.
Why a “Dome”
The radiation pattern of a quadrifilar antenna is close to hemispherical: it works with equal confidence both along the horizon and against targets approaching from above — which is the primary attack scenario for bomb-drops and diving FPVs. This is what gave an entire class of solutions its name — “dome EW”: the antenna forms a continuous countermeasure zone above a position, vehicle, or object.
Thanks to this, the quadrifilar equally and correctly receives and re-radiates both horizontally and vertically polarized signals.
Single-Band and Multi-Band Solutions
The choice usually comes down to two approaches:
- Single-band antenna. Tuned to a specific frequency (for example, dedicated to the control channel or separately to the video channel). Simpler, cheaper, easier to configure — justified when the specific type of threat is known.
- Multi-band antenna. Covers several bands simultaneously — relevant now, when the adversary is actively changing control and video frequencies within a single sortie. In 2026, most new dome complexes are being designed specifically for wideband coverage, since single-band solutions cannot keep up with the rapid frequency changes in FPV.
| Antenna type | Polarization | Strength | Typical application |
| Quadrifilar (QHA) | Circular | Dome coverage, resilience to target maneuvering | Protection of positions, vehicles, checkpoints |
| Patch antenna | Linear/circular (depending on configuration) | Compactness, stability at 2.4/5.8 GHz | Mobile and stationary complexes, video channel suppression |
| Sector antenna | Linear | Long range in a narrow direction | Covering the likely drone approach direction |
| Whip (cloverleaf) | Linear | Low cost, simplicity | Universal budget solutions |
| HELIX | Circular | Range at 5.8 GHz | Challenging conditions, significant distance to target |
Where all-round defense of a position from every direction and from above is needed, the quadrifilar antenna remains the optimal choice. Where the priority is range along a specific direction, a patch or sector antenna will be more effective. That is why positions are increasingly combining both antenna types.
What to Look for When Choosing
- Frequency range. Verify coverage of the control and video channels of the drone types the unit encounters.
- Structural protection. A dome-type design must withstand wind, precipitation, temperature extremes, and transportation — an antenna without a protective radome fails quickly in the field.
- Mobility. For vehicle mounting, weight, mounting hardware, and vibration resistance are important. For stationary protection, coverage area matters more.
- Compatibility with the EW complex. An antenna is effective only together with a transmitter of adequate power and a controller, so it should be selected for a specific system.
Conclusion
A quadrifilar antenna provides the formation of a circular protective dome where a threat can come from any direction. Combined with patch or sector antennas, it delivers balanced coverage both in terms of range and attack angle.
A range of dome quadrifilar antennas (300–1050 MHz) and other EW solutions is available in the BlueBird company catalog.