Clever Phasing with 4 Cardinal BoG Antennas: 8 Directions, Minimal Gain Tradeoff

Low-band DXing often comes with the challenge of directional reception. While single long beverages or BoG antennas offer great front-to-back performance, they're fixed in direction. What if you could achieve 8 unique directions using just 4 antennas? Enter clever phasing with the PulseRoot 100 system, our active beverage on ground with passive but dynamic termination!

The Setup

Use four PulseRoot 100 active RX antennas placed in a cardinal layout:

  • North
  • East
  • South
  • West

Each PulseRoot 100 consists of a 100-meter long Beverage-on-Ground (BoG) antenna with active amplification and balanced low-output impedance, making it ideal for phasing applications.

How It Works: Phasing for 8 Directions

By combining these four antennas with appropriate phasing and delay lines, you can synthesize 8 distinct reception directions in 45-degree steps:

  • The four cardinal directions (N, E, S, W) are used as primary vectors.
  • By phasing two adjacent antennas (e.g., N + E, or S + W) with proper delay and amplitude balance, you get intercardinal directions: NE, SE, SW, NW.

This approach takes advantage of the PulseRoot 100's natural beamwidth of approximately 100 degrees (-3 dB), making 45-degree spacing practical and efficient without excessive overlap or gaps.

Why Gain Isn’t Lost

At first glance, combining four antennas might seem like you're splitting your signal four ways. But when phasing is done correctly:

  • You get constructive interference in your desired direction.
  • Signals in other directions undergo destructive interference or partial cancellation.
  • The net result is directional gain similar to a single long beverage, typically around 6 to 8 dB.
  • The "aperture" is extended virtually through phasing, not physical wire.

Because the BoGs are independent sources, and not passively split and each has its own LNA, you don't suffer the typical 3 dB combining loss like with passive arrays. This is a critical advantage.

Why It Works So Well

  1. Stable phase centers: Because the BoGs are electrically short for RX at 160/80/60m, spacing and delay management are more forgiving.
  2. Low interaction: Being on the ground and unpowered except at the terminals, the BoGs have minimal mutual coupling.
  3. Built-in gain: Each PulseRoot 100 amplifies the signal before transport, preserving dynamic range.
  4. High common-mode rejection: Differential output helps eliminate noise loops and interaction via coax.

Technical Summary

Parameter Value
Number of RX Antennas 4 (cardinal: N, E, S, W)
Antenna Type Beverage on Ground (100m)
System Gain +15 dB typical (preamp gain)
Directional Steps 8 (every 45 degrees)
Polar Coverage Full 360°
Coupling Loss Negligible (active isolated feeds)

In Practice

You can build this phasing matrix with analog 0/90/180-degree hybrids and adjustable delay lines. For traditional operators, the upcoming BoG Phazer4 control box will allow you to select one of the 8 preset directions and present a single output signal — no complex switching or SDRs required.

Closing Thoughts

Phasing four PulseRoot 100 antennas into an 8-direction receive system is a high-performance, low-footprint alternative to large antenna farms or costly rotatable systems. And because each direction is synthesized by combining already-deployed elements, the added complexity is in the combining logic, not the field installation.

If you spot a technical inconsistency or want to adapt this to your specific use case (shorter BoGs, hilly terrain, different spacing), don’t hesitate to contact us. We improve these articles based on your field observations!

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Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.