| Operating Frequency | FM broadcast band, commonly 87.5–108 MHz; the exact legal band varies by country or region. | Confirm that the transmitter covers the permitted frequency range and supports the channel spacing required by the local regulator. | All applications, especially licensed broadcast and community radio. |
| Legal Authorization | Unlicensed low-power operation, licensed low-power broadcasting, or full-power licensed broadcasting. | Check local licensing rules, maximum permitted field strength or effective radiated power, frequency coordination, and registration requirements before transmission. | The legal category must match the intended coverage and installation location. |
| RF Output Power | Very low power: up to approximately 1 W; low power: approximately 1–100 W; higher-power systems: above 100 W. | Do not select power based only on desired distance. Regulations may limit transmitter power, antenna gain, cable loss, and total radiated power. | Use the lowest legal power that provides reliable coverage without causing interference. |
| Coverage Requirement | Room or site coverage, campus or event coverage, neighborhood coverage, or wider regional coverage. | Evaluate terrain, building materials, antenna height, frequency congestion, and the permitted radiated power. | A coverage study is preferable for permanent or licensed installations. |
| Audio Inputs | Balanced XLR, unbalanced RCA, 3.5 mm stereo, digital audio, or network audio. | Match the transmitter input to the mixer, computer, studio processor, or mobile device. Check nominal level, impedance, stereo support, and connector type. | Balanced inputs are useful for long cable runs; stereo inputs suit music and general entertainment programming. |
| Audio Processing | Basic pre-emphasis, stereo encoding, limiter, compressor, or external audio processor. | Verify the required pre-emphasis standard for the region, stereo pilot accuracy, deviation control, and protection against overmodulation. | A controlled audio chain improves intelligibility and reduces interference risk. |
| Frequency Stability | Crystal-controlled, digitally synthesized, or temperature-compensated frequency generation. | Look for published frequency tolerance, automatic frequency control, and protection against drift during temperature changes. | Stable frequency generation is important where nearby channels are occupied. |
| Antenna Compatibility | External quarter-wave, half-wave, dipole, ground-plane, or directional antenna. | Confirm the antenna frequency range, polarization, connector type, impedance—normally 50 ohms for RF equipment—and power rating. | Use a properly tuned antenna system rather than relying on an improvised wire antenna. |
| VSWR Protection | No protection, warning indicator, automatic power reduction, or automatic shutdown. | Choose protection that reduces damage from poor matching, disconnected feed lines, water ingress, or antenna faults. | Strongly recommended for unattended and outdoor installations. |
| Installation Type | Portable, desktop, rack-mounted, vehicle-mounted, or fixed outdoor installation. | Check enclosure size, mounting hardware, ventilation, weather protection, cable routing, and access for maintenance. | Portable units suit temporary events; rack-mounted units suit studios and equipment rooms. |
| Power Supply | AC mains, low-voltage DC, battery, or redundant power supply. | Match voltage, frequency, polarity, current capacity, grounding, and applicable electrical safety requirements. | Battery or DC operation is useful for temporary and remote installations. |
| Cooling and Environment | Fan-cooled indoor chassis, sealed outdoor enclosure, or climate-controlled equipment-room installation. | Review operating temperature, humidity limits, ventilation clearance, dust protection, and condensation control. | Outdoor systems need suitable weatherproofing and surge protection. |
| Regulatory and EMC Compliance | Applicable radio, electromagnetic compatibility, electrical safety, and environmental compliance markings. | Verify documentation for the country of operation. Compliance markings do not replace a required operating license. | Essential for commercial, public, permanent, and imported installations. |
| Interference Control | Adjustable frequency, output filtering, harmonic suppression, shielding, and deviation monitoring. | Check unwanted emissions, frequency accuracy, modulation limits, and whether technical measurements are required after installation. | Prioritize these features in congested urban areas and near sensitive radio services. |
| Monitoring and Control | Front-panel controls, remote web interface, telemetry, alarms, or external power monitoring. | Confirm secure access, event logging, alarm outputs, and local control availability if the network fails. | Remote monitoring reduces service time for unmanned sites. |
| Safety and Site Protection | Grounding, lightning protection, surge protection, RF exposure controls, and restricted access. | Follow local electrical codes and RF exposure limits. Keep people away from high-power antennas and energized RF components. | Required for rooftop, tower, outdoor, and higher-power installations. |