Site Planning
Choosing locations and understanding what affects coverage.
Choosing a Repeater Location
Location is the single most important factor in a repeater's effectiveness. A mediocre antenna on a perfect hilltop will outperform an excellent antenna at ground level every time.
Elevation is everything
Radio waves travel in straight lines. The higher your repeater, the farther it can see before the curvature of the earth and obstacles block the signal. Every additional meter of height extends the radio horizon.
Location types - best to acceptable
Hilltops and ridgelines
The gold standard. A repeater on a hilltop with unobstructed 360-degree views can cover a 20 - 25 mile radius. Even a modest hill of 100 - 200 feet above the surrounding terrain makes a significant difference.
Rooftops
Excellent for urban and suburban coverage. The highest accessible rooftop in a neighborhood, mounted on a pole or parapet wall, provides clear line-of-sight in most directions.
Communications and water towers
Already optimized for radio coverage. Many amateur radio operators and property owners are open to hosting community infrastructure.
Tall trees
A practical option for rural or forested areas. Mount as high as safe access allows and ensure the solar panel receives adequate sunlight throughout the day.
Balconies and upper-floor windows
The minimum viable option when rooftop access is unavailable. Orient toward the direction offering the clearest line of sight. Even a second-floor position is meaningfully better than ground level.
What to avoid
- Low ground - valleys and depressions block signal in nearly all directions
- Dense tree cover at antenna level - trees absorb 915 MHz signals significantly
- Large metal structures nearby - HVAC equipment and metal roofing reflect and detune signals
- Fully indoor placement - walls absorb a significant fraction of signal strength
Testing before committing
Before a permanent installation, test with a temporary mount. Walk around the intended coverage area while watching signal on a paired phone. Tools like HeyWhatsThat can help visualize the theoretical radio horizon from a given point, though they do not account for buildings or vegetation.
Antenna Selection and Mounting
The antenna matters more than the radio
For a fixed repeater, the antenna is often the most impactful upgrade available. Moving from a 2 dBi stock antenna to a 6 dBi vertical on a rooftop pole can add 4 dB of gain while simultaneously improving line-of-sight.
Antenna types for repeaters
Omnidirectional vertical (most common)
Radiates equally in all directions horizontally - ideal for a repeater that needs to serve a wide area. Higher gain (dBi) concentrates the signal closer to the horizontal plane, extending horizontal range but reducing coverage of areas directly below. For elevated repeaters, 3 - 6 dBi is usually optimal. Very high gain antennas can create a dead zone directly beneath them.
Directional (Yagi, patch)
Focuses energy in one direction for maximum reach between two specific points. Requires careful aiming and is not suitable for general area coverage.
Gain vs. coverage angle
| Gain | Horizontal range | Best use |
|---|---|---|
| 2 - 3 dBi | Short | Ground-level or indoor use |
| 5 - 6 dBi | Medium - long | Most rooftop repeaters |
| 8 - 9 dBi | Long, narrow beam | Tall towers covering flat terrain |
Cable quality
Coaxial cable losses add up at 915 MHz. Use the shortest cable run possible. For runs over 3 meters, use low-loss cable (LMR-200 or equivalent). Weatherproof all outdoor connector joins with self-amalgamating tape or appropriate connector covers.
Key mounting rules
- Mount the antenna as high as practical, clear of obstructions in all directions
- Keep the cable run short - locate the radio enclosure close to the antenna rather than running a long cable
- Use stainless steel hardware outdoors to prevent rust and galvanic corrosion
- Never power on the radio without an antenna connected - transmitting into an open connector can permanently damage the transmitter