← Standards & Specs
The Toolbox — Standards
RF & Antenna
Antenna installation requirements, coaxial cable specifications, and RF safety standards.
Antenna Installation
| Specification | Value / Notes |
|---|---|
| VHF marine antenna impedance | 50 ohms |
| Maximum SWR (recommended) | 1.5:1 or lower |
| Aviation antenna bonding resistance | Less than 3 milliohms DC to airframe ground |
| VHF antenna height (marine) | Masthead preferred — each doubling of height adds ~40% range |
| Quarter-wave vertical feed impedance | Approximately 35 ohms |
| Half-wave dipole feed impedance | Approximately 72 ohms |
| Standard RF system impedance (marine/aviation) | 50 ohms |
| 75-ohm systems | Cable TV, video, satellite — not used for marine/aviation |
| VHF marine antenna gain (typical) | 3 dBd (6 ft whip) to 6 dBd (8 ft whip) |
| Antenna polarization (VHF marine) | Vertical |
| Antenna polarization (VHF aviation) | Vertical |
| Maximum feedline loss recommended | 3 dB or less from radio to antenna |
Coaxial Cable
| Specification | Value / Notes |
|---|---|
| Standard RF impedance (marine/aviation) | 50 ohms |
| RG-58 loss at 150 MHz | Approx 6 dB per 30 meters |
| RG-8X loss at 150 MHz | Approx 3 dB per 30 meters |
| RG-213 loss at 150 MHz | Approx 2.5 dB per 30 meters |
| LMR-400 loss at 150 MHz | Approx 1.5 dB per 30 meters |
| RG-58 velocity factor | 0.66 |
| LMR-400 velocity factor | 0.85 |
| Minimum bend radius (RG-58) | 3.8 cm |
| Minimum bend radius (RG-8X) | 5 cm |
| Minimum bend radius (LMR-400) | 10 cm |
| RG-58 max power at 30 MHz | Approx 500 watts |
| LMR-400 max power at 30 MHz | Approx 5,000 watts |
RF Safety & MPE
| Specification | Value / Notes |
|---|---|
| MPE averaging time — controlled environment | 6 minutes |
| MPE averaging time — uncontrolled environment | 30 minutes |
| MPE study required above | 1,000 watts ERP aggregate |
| Multi-antenna sites — threshold for inclusion | Any antenna contributing more than 5% of MPE limit |
| Personnel RF safety training frequency | Annually |
| VHF/UHF MPE limit (general population) | 1.0 mW/cm² at 30–300 MHz |
| FCC RF safety reference | OET Bulletin 65, FCC Part 1 Subpart I |