In-Building Wireless Solutions
ERCES & Cellular DAS Specialists — Northern California
Interactive Reference Guide

Cellular DAS System Components

Distributed Antenna System — complete component reference for passive and active DAS, with specifications, design considerations, and carrier coordination notes.

Passive DAS Active DAS Small Cell 4G LTE 5G NR CBRS FCC Part 20
Most common — IBWS specialty

Passive DAS

Uses a donor antenna or small cell as the signal source, distributed through passive coaxial splitters and cable. Cost-effective, faster to deploy, ideal for most commercial buildings under ~500,000 sq ft. No fiber required. IBWS specializes in this approach.

Large venues / high capacity

Active DAS

Uses fiber-connected remote units (RUs) driven by a central base station hotel. More complex and expensive, but required for stadiums, large campuses, and high-density venues where many users are on the same carrier simultaneously.

Passive DAS signal path — macro to user device
Macro cell tower → Donor antenna → BDA / signal source → RF splitter → Trunk & tap cables → Remote antennas → User devices

Click any component card for full specifications, design notes, and carrier coordination guidance

Signal Source
Macro donor antenna, small cell, or carrier base station
5 components
Macro cell tower (outdoor)
Carrier base station — source of outdoor signal
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Donor antenna
Rooftop — captures macro signal over-the-air
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Carrier small cell
Dedicated indoor base station per carrier
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CBRS / private LTE node
3.5 GHz shared spectrum — enterprise / managed
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Surge suppressor
Lightning protection at coax building entry
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Head-End Equipment
BDA, combiner, power — signal conditioning before distribution
4 components
Bi-directional amplifier (BDA)
Amplifies signal from donor antenna
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Multi-carrier combiner
Merges signals from multiple carriers into one coax
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Band-pass filter
Isolates target frequencies, blocks interference
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UPS / backup power
Keeps system online during outages
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Distribution Infrastructure
Coax, splitters, taps — passive signal routing through the building
4 components
RF splitter / power divider
Divides signal across zones or floors
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Coaxial trunk cable (riser)
½" or ⅞" plenum-rated vertical backbone
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In-line tap / directional coupler
Drops signal to each floor from trunk
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In-line signal booster
Compensates cable loss on long runs
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Remote Antennas & Radiating Elements
Last-mile coverage — ceiling, wall, and distributed radiating
4 components
Omni-directional antenna
360° — open floors, corridors, common areas
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Panel / directional antenna
Focused beam — garages, stairwells, edges
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Pico cell / active remote unit
Active DAS — fiber-connected remote radio
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Leaky coax (radiating cable)
Tunnels, elevator shafts, dense concrete
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Carrier Coordination, Testing & Management
FCC compliance, carrier agreements, performance verification
5 components
Pre-installation RF survey
Outdoor RSSI map and propagation study
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Carrier coordination / agreement
Required before activating BDA or small cell
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FCC Part 20 / equipment certification
All BDAs must be FCC certified
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Post-installation testing
Drive / walk test — RSRP, RSRQ, throughput
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Network management system (NMS)
Active DAS monitoring and fault alerting
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Select any component above to view full specifications, design notes, and carrier coordination guidance.

Cellular coverage issues in your building?

IBWS designs and installs cost-effective passive DAS solutions — faster and less expensive than active DAS for most buildings.

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