700 MHz Antenna Installation Tips

　　700 MHz Antenna Installation Tips

　　Ensure Optimal Signal Performance and Longevity

　　700 MHz antennas are widely used in public safety, rural broadband, and IoT networks and require careful installation to fully utilize their long-range and penetration capabilities. Proper installation, calibration, and environmental protection measures have a direct impact on signal strength and system reliability. This guide provides practical tips to help you maximize performance during and after installation.

　　1. Pre-installation planning

　　Site survey and obstacle assessment

　　Line of sight verification: 700 MHz signals penetrate obstacles better than higher frequencies, but are still attenuated by dense materials (concrete, steel). Use a drone or binoculars to identify potential obstructions (tall trees, buildings) within a 5 km radius of the installation site. Prioritize locations with a clear view of the target coverage area.

　　Interference detection: Use a spectrum analyzer to scan for nearby 700 MHz signals that may cause co-channel interference (e.g., TV transmitters, public safety radios). Choose a site at least 300 meters away from such interference sources and plan to use a bandpass filter if relocation is not possible.

　　Equipment compatibility check

　　Impedance matching: Make sure the antenna (50 ohm) matches the transceiver and coaxial cable (e.g., LMR-400) to avoid voltage standing wave ratio (VSWR) issues. System mismatch can cause up to 30% signal loss.

　　Connector compatibility: Verify that the antenna connector (N-type, SMA) aligns with the cable and transceiver. Use adapter kits only when necessary as they introduce additional insertion loss (≤0.3 dB).

　　2. Optimal location selection

　　Height and altitude

　　Coverage height: For rural areas, antennas should be mounted at least 10 meters above the ground to improve coverage. In urban areas, rooftop mounting (15-20 meters) can reduce building shadowing and increase coverage by 20-30%.

　　Avoid ground reflections: Mount the antenna above reflective surfaces (metal roofs, water bodies) to minimize multipath interference. Maintaining a 3-meter vertical clearance between the antenna and such surfaces stabilizes signal reception.

　　Environmental Protection

　　Weather Exposure: Mount the antenna in a location that avoids direct gusts of wind (≥60 km/h) to prevent vibration-induced signal fluctuations. In areas with strong winds, use a wind shield or guy wire for pole-mounted antennas.

　　Temperature Considerations: In desert or Arctic regions, choose a thermally insulated mounting bracket to protect the antenna from extreme temperatures (-40°C to +85°C). Avoid mounting near heat sources (e.g. HVAC equipment, engines) that may exceed the antenna's operating range.

　　3. Mounting and Alignment

　　Safe Mounting Techniques

　　Pole Mounting: Use a 2-3 inch (approximately 5-8 cm) diameter galvanized steel pole with a tilt bracket for adjustment. Secure the antenna with U-bolts (torque to 25 N·m) and add shock absorbers to reduce mechanical stress on the coaxial cable.

　　Roof Mounting: For flat roofs, use a weighted base (≥50 kg) to avoid penetration of the roof. For pitched roofs, secure it to the rafters with lag bolts (stainless steel) to ensure stability during storms.

　　Polarization and Directional Alignment

　　Omnidirectional Antennas: Ensure vertical polarization by aligning the antenna’s radiating element parallel to the ground. Use a level to confirm verticality, as a 10° tilt can result in a 3 dB decrease in signal strength.

　　Directional Antennas (Yagi, Panel): Use a compass or GPS to align the antenna with the target receiver (e.g., a base station in the distance). A laser level helps fine-tune the horizontal alignment, ensuring that the narrow beam (30°–60°) is aimed directly at the receiver. Even a 5° deviation can result in a 50% reduction in coverage.

　　4. Cable Routing and Protection

　　Minimize Signal Loss

　　Cable Length Optimization: Coaxial cable length should be kept to 30 meters to limit attenuation (LMR-400 should have ≤3 dB attenuation at 700 MHz). For longer distances, use low-loss cables (e.g., LMR-600) or install a signal amplifier (with 15 dB gain) near the antenna.

　　Bend Radius Compliance: Maintain a minimum bend radius of 10 times the cable diameter (e.g., 50 mm for LMR-400) to avoid damage to the inner conductor. Use plastic clips (not metal ties) to secure the cable to prevent kinking.

　　Weatherproof Connections

　　Connector Sealing: Before mating, apply dielectric grease to the male connector, then wrap the connector with three layers of self-fusing tape (overlapping 50%), followed by UV-resistant electrical tape. This prevents moisture infiltration, which is the main cause of corrosion in outdoor installations.

　　Cable Entry Point: Use cable glands (IP67 rating) when passing through walls or cabinets. Seal gaps with silicone sealant to keep out dust and insects.

　　5. Grounding and Lightning Protection

　　Proper Grounding

　　Electrical Grounding: Connect the antenna bracket to a dedicated ground rod (8 feet long, copper-plated) using 6 AWG stranded copper wire. Grounding resistance should be ≤5 ohms to dissipate static electricity and lightning current.

　　Coaxial Cable Grounding: Install a surge protector (rated at 700 MHz) within 1 meter of the antenna. This protects the transceiver from voltage spikes while minimizing signal loss (≤0.5 dB).

　　Lightning Mitigation Measures

　　Avoid tall buildings: Install the antenna at least 5 meters away from a nearby lightning rod or tall tree to reduce the risk of lightning strikes. For stand-alone installations, install a lightning rod 2 meters above the antenna and connect to the same grounding system.

　　6. Post-Installation Testing and Maintenance

　　Signal Performance Verification

　　VSWR Test: Use a VSWR meter to confirm that the reading is ≤1.5:1. Values >2:1 indicate a faulty connection or a bad antenna, requiring immediate troubleshooting.

　　RSSI Monitoring: Deploy a temporary receiver at the edge of the coverage area to measure received signal strength. The ideal value is -80 to -100 dBm; weak signals (-110 dBm or less) indicate alignment or installation issues.

　　Routine Maintenance

　　Quarterly Inspection: Check for loose connections, corrosion, or physical damage (e.g., cracked fiberglass housing). Clean connectors with isopropyl alcohol and reapply dielectric grease annually.

　　Seasonal Adjustment: In areas with heavy snowfall, clear ice and snow from antennas to maintain radiation efficiency. For coastal areas, check for salt spray corrosion every 6 months.