Antenna Placement — ELRS RX and VTX

calendar Jul 13, 2026 · 4 min read · fpv elrs antenna rf placement range vtx diversity  ·
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Antenna placement is one of the most overlooked range factors. A perfectly tuned ELRS link loses 10–20 dB when the antenna is oriented wrong — the equivalent of cutting TX power by 90%.

Why Antenna Orientation Matters

Omnidirectional antennas (dipoles, linear, RHCP/LHCP) have a radiation pattern shaped like a donut — strong equatorially, near zero at the tips (the "null").

flowchart LR
    subgraph "Side view — dipole pattern"
        direction TB
        T([Antenna tip<br/>← NULL]) 
        M([Maximum gain<br/>→ 360° around equator])
        B([Antenna base<br/>← NULL])
    end

If the TX antenna tip points directly at the RX, or the RX antenna tip points directly at the TX, signal strength drops to near zero even at close range. This is called a null.

Omnidirectional means "equal in all directions around the equator" — not "equal in all directions period."

RX Antenna Rules

Rule 1 — Perpendicular to the frame

Mount the RX antenna(s) so the element runs perpendicular to the main flight axis (not pointing nose/tail). The equatorial gain ring should face forward/backward/sideways.

1Good:                   Bad:
2   [antenna]            [RX]
3       |                  |
4  _________           [antenna]   ← tip points up = null when quad is below TX
5 |   FC    |              |
6 |   ESC   |              ↓ (pointing down = null when TX is above)

Rule 2 — Clear of carbon fiber

Carbon fiber is conductive and attenuates RF. Keep the active element (the tip portion of the dipole or the entire element for linear dipoles) out of the frame shadow.

Route the antenna through a small hole in the rear arm, or use a 3D-printed antenna mount that angles it 45° away from the frame.

Rule 3 — 90° separation on diversity RX

If your receiver has two antennas (diversity), orient them 90° to each other. When one antenna is in a null, the other has near-maximum gain — the diversity logic picks the stronger signal.

1Diversity RX antenna orientation:
2Antenna A: horizontal (along arm)
3Antenna B: vertical (up through tail)
4
5Coverage:         A covers front/back/sides
6                  B covers above/below
7Combined:         Near-spherical coverage

VTX Antenna Rules

The VTX antenna transmits the video signal. The same null problem applies — if the receive antenna (goggles) is in the null, you get snow or dropout.

For 5.8 GHz video, use a circularly polarized antenna on both ends (RHCP or LHCP), matching polarization. Circular polarization eliminates nulls from rotation because the signal strength doesn't depend on rotational alignment.

  • RHCP (Right Hand Circular Polarized) — common default; TBS, Pagoda, Lumenier antennas
  • LHCP — less common; mixing polarization causes ~20 dB loss

Mount the VTX antenna away from the carbon frame and away from the RX antennas. 2.4 GHz ELRS and 5.8 GHz video don't interfere directly (different frequencies) but close proximity can cause interaction.

Common Placement Mistakes

flowchart TD
    M1[❌ RX antenna zip-tied flat<br/>to bottom of frame] -->|Carbon shadow<br/>blocks signal| F1[Poor rearward range]
    M2[❌ Antenna tip pointing<br/>directly at TX] -->|Null zone<br/>full null at 0°| F2[Unexpected drops<br/>at close range]
    M3[❌ VTX antenna touching<br/>carbon arm] -->|Detuning + SWR<br/>increases ESC noise| F3[Short range<br/>VTX runs hot]
    M4[❌ Both diversity antennas<br/>parallel to each other] -->|No coverage<br/>improvement| F4[Same null<br/>on both antennas]
    M5[❌ LHCP on quad<br/>RHCP on goggles] -->|Cross-polarization<br/>loss ~20 dB| F5[Very short range<br/>cannot compensate with power]

ELRS 2.4 GHz vs 900 MHz Antenna Sizes

BandHalf-wave dipole lengthNotes
2.4 GHz~62 mmShort; easy to fit on any build
900 MHz~166 mmLong; needs careful routing on 5"
433 MHz~345 mmVery long; mainly for fixed-wing

900 MHz antennas are physically large on a 5" quad — the long element needs to be routed along an arm or angled outward. On a micro quad, 2.4 GHz is almost always the better choice due to antenna size constraints.

Quick Checklist

  • RX antenna element clear of carbon, pointing perpendicular to nose axis
  • Diversity antennas 90° to each other
  • VTX antenna not touching frame
  • VTX and goggles using matching polarization (both RHCP or both LHCP)
  • No antenna connector fully tightened while quad is under power (SMA torque can crack the VTX PCB pad)

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