What actually goes wrong with wireless, and how to not do it.

Antenna Placement

Do

• Mount RX antennas with direct line of sight to the performance area; 2–3 m above stage floor, away from truss steel and rigging.
• Keep RX antennas at least 3 m apart for diversity (or use a directional + diversity pair).
• Use active directional antennas (paddle/log-periodic) for venues over 15 m or with PA/LED interference.
• Keep TX (body-pack/handheld) at least 5 m from the RX antenna — any closer and you desensitize the input stage.
• Match TX and RX antenna polarization — both vertical or both horizontal; mixing costs 3–20 dB.

Avoid

• Do not tape antennas flat to metal, drywall studs or LED video walls — they detune and shadow them.
• Do not hide RX antennas in the FOH world — this is about RF, not aesthetics.
• Do not coil excess antenna cable — bundle it loosely; tight loops make RF chokes.

Rule of thumb: if you cannot see the antenna from where the performer stands, the antenna cannot see the performer either.

Squelch & Gain Staging

What squelch is

A noise gate on RX RF input that mutes audio when no signal (or no valid signal) is detected. Stops you from broadcasting hiss when a pack powers off mid-show.

Squelch types

• Noise squelch: opens on signal strength only. Cheap, but opens on any RF spike (walkie, lighting dimmer, EMI).
• Pilot tone: the RX only opens on a specific sub-audible tone from its paired TX. Use this — it is standard on professional systems.
• Code/encrypted squelch: RX opens only on a unique digital code per TX. Standard on Shure ULX-D, Sennheiser EW-DX, etc.

Gain staging

• TX input gain: set so loudest passage hits −6 to −3 dB on the pack meter — no clipping, no buried signal.
• RX AF output: nominal line level into your console (typically 0 dBu or +4 dBu). Console preamp at unity or below.
• If the RX AF runs hot and the console preamp runs low, you are starving your SNR.

Squelch is a safety net, not a fix for bad gain staging.

RF Overload & Intermodulation

What goes wrong

• Two strong nearby transmitters mix inside the RX front end and create 3rd-order intermodulation (IM3) products at predictable frequencies (2f₁−f₂ and 2f₂−f₁). These spurs land on top of your other channels.
• The intermod chip in this panel flags coordination windows that fall on known IM3 zones — trust it.

How to avoid it

• Keep TX antennas off your own RX antennas — minimum 5 m, more is better.
• Do not pile TX packs together backstage before the show — keep 1 m apart or switch them off.
• Coordinate frequencies using this app's safe windows — do not pick channels by ear.
• Fit an RF attenuator (3–10 dB) at the RX input when working indoors with a high local RF noise floor or nearby PA bands.
• Use a bandpass filter at the antenna distro input to reject out-of-band cellular/LTE spillover.

If you scan and the noise floor jumps when packs are on but idle, you have IM3 — recoordinate.

Battery & Body-Pack Hygiene

Power

• Use lithium primary (e.g. Energizer Ultimate Lithium) or rechargeable Li-ion (Sennheiser BA 70, Shure SB900). Skip alkaline for shows — voltage sag kills RX squelch mid-scene.
• Check battery curve, not just % — alkaline reads 80% then drops to 0 in 30 min; lithium holds flat.
• Always fresh batteries for ≥2-hour blocks. Spares within arm's reach of the monitor desk.

Body-pack on talent

• Pack worn at small of back or hip, antenna pointing away from skin (sweat detunes the antenna).
• Strain-relief the lavalier cable — loop once and clip; cable yank = dead mic mid-line.
• Lavalier 6–8 inches below the chin, capsule pointing up; tape it to skin if costume permits.
• Use sweat covers (3M Tegaderm, mic-specific moisture caps) for theatre runs.

The mic capsule is the cheapest part of the chain to lose and the most expensive to replace mid-show.

Coordination Workflow

Before the show (1 hour minimum)

• Scan the venue with an RF analyzer (RF Explorer, Sennheiser Spectera, Shure Wireless Workbench scan). Capture the RF floor with PA + lighting on, not off.
• Pick your region in this app and load your manufacturer band.
• Use the green coordination windows — they are filtered against the current TV channel plan and IM3 danger zones for your selection.
• Lock in frequencies on TX and RX, walk the stage, watch RX signal/AF meters. Drop any window that goes intermittent.
• Save presets with descriptive names ("Stage L vocal", not "Ch 1").

During the show

• Monitor RX RF and AF meters at FOH or monitor world. Drops show as RF meter dips before audio breaks.
• Have a backup frequency per channel preloaded — switch via TX scroll if a band goes hot mid-show.

Scan early, scan late, and scan whenever the venue RF environment changes (load-in vs. doors vs. full house).

Regulatory Walkthrough

For every show, confirm:

• Region selector (top of page) matches the country you're physically in.
• Manufacturer band falls inside a coordination window for that region.
• Regulatory status for the band shows Free / Frei (no application needed) OR you hold a current license for the Required / Pflicht band.
• TX output power matches the limit for that band (typical: 10 mW SRD, 50 mW VHF/UHF General Authorization, 100 mW AU LIPD, 250 mW US Part 74).
• No coordination windows touch a sunset window (e.g. DE Ch49+ 5G handover, UK Ch38 Ofcom guard) for the date of your event.

Common mistakes

• Using a US-bought Part 74 mic at 250 mW in DE — exceeds 50 mW General Authorization limit. Reduce power or use locally-compliant gear.
• Trusting a wireless system that "worked at the last venue" in a new country — band plans differ.
• Assuming a "license-free" band is universal — 863–865 MHz is, 1785–1805 is mostly EU/AU only.

This page is informational. Final compliance rests with the operator — check against your regional regulator's current database.