Why the VerticalVortex Excels at Low-Angle DX Reception (But Not NVIS)

It’s a Vertical – and Verticals Don’t Do NVIS

The VerticalVortex is a vertical antenna, and as such:

  • It has maximum sensitivity at low elevation angles, close to the horizon.
  • It has very poor sensitivity straight up (high elevation angles).

This is the exact opposite of what you need for NVIS (Near Vertical Incidence Skywave), which relies on:

  • Radiating and receiving nearly straight up, so the signal reflects back down to Earth within ~500 km.

So:

  • Bad for NVIS: The VerticalVortex has a deep null overhead, meaning high-angle signals (like local skywave) are strongly attenuated.
  • Good for DX: It picks up the low-angle signals that travel long distances via shallow skywave hops.

Low Angle = Long Distance

On 160 and 80 meters:

  • DX signals arrive at 5° to 20° elevation, especially at night when D-layer absorption drops.
  • The VerticalVortex is optimized to listen in this low-angle range, rejecting local high-angle QRM and favoring distant signals.

This makes it especially useful for:

  • DXing during greyline or night-time conditions
  • Receiving weak transcontinental signals that NVIS-style antennas (like low dipoles) won’t hear well

RX Antenna Design Tailored to Propagation Mode

Most hams use NVIS antennas like low dipoles or loops for regional coverage on 80 m — which works great for traffic nets, ragchews, or emergency comms.

But if your goal is:

  • DX contacts on Top Band (160 m) or 80 m
  • Listening to weak signals from across continents or oceans

Then you need a receive antenna that favors low-angle arrival paths.

That’s exactly what the VerticalVortex does:

  • Omnidirectional
  • Low-noise
  • Low-angle
  • Perfect for 160/80 m DX reception

Summary

Use Case Desired Elevation VerticalVortex
NVIS High angle (60–90°) ❌ Poor (deep null)
DX Low angle (5–25°) ✅ Excellent (peak gain)

 

So while it’s not your best friend for local nets, the VerticalVortex is a DX hunter’s dream on 160 and 80 meters.

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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.