73 Wireless Range Calculator

Link Budget and Path Loss Estimation Tool

73.1 Wireless Range Calculator

Learning Objectives

By using this interactive tool, you will be able to:

Calculate expected wireless range for IoT deployments
Understand link budget components (TX power, antenna gain, path loss)
Compare different protocols and frequencies
Design reliable links with safety margins

For Beginners: What Determines Wireless Range?

Range depends on simple physics: How much power you send vs. how much you need to receive.

Factor	Effect on Range
Higher TX power	Longer range
Better antenna	Longer range
Lower frequency	Longer range (better penetration)
More obstacles	Shorter range
Higher data rate	Shorter range

The Link Budget Equation:

Received Power = TX Power + TX Antenna Gain - Path Loss + RX Antenna Gain

If Received Power > Receiver Sensitivity, communication works!

73.2 Quick Start: Deployment Scenarios

Common IoT Deployment Configurations

Scenario	Protocol	Environment	Expected Range	Key Considerations
Smart Home	Wi-Fi/BLE	Indoor (walls)	10-30m	Wall penetration, interference
Building Automation	Zigbee/Thread	Indoor (open)	30-100m	Mesh extends range
Campus Monitoring	LoRa	Suburban	2-5km	Gateway placement critical
Agriculture	LoRa (SF12)	Rural/Open	10-15km	Line of sight preferred
City Parking	NB-IoT	Urban dense	1-2km (cell)	Carrier coverage dependent
Asset Tracking	BLE beacons	Indoor	10-50m	Beacon density matters
Industrial Plant	Zigbee	Industrial	30-100m	Metal interference, mesh helps

Range Planning Tips:

Always add fade margin (10-20 dB) for reliable operation
Measure, don’t assume - do site surveys before deployment
Consider worst case - rain, interference, battery aging
Plan for growth - leave headroom for additional devices

73.3 Protocol Selection

Show code

protocols = [
  {name: "LoRa (SF12)", freq: 868, txPower: 14, rxSensitivity: -137, bandwidth: 0.29, color: "#F39C12"},
  {name: "LoRa (SF7)", freq: 868, txPower: 14, rxSensitivity: -123, bandwidth: 11, color: "#E67E22"},
  {name: "Sigfox", freq: 868, txPower: 14, rxSensitivity: -126, bandwidth: 0.1, color: "#8E44AD"},
  {name: "NB-IoT", freq: 800, txPower: 23, rxSensitivity: -141, bandwidth: 200, color: "#1ABC9C"},
  {name: "LTE-M", freq: 800, txPower: 23, rxSensitivity: -107, bandwidth: 1000, color: "#E74C3C"},
  {name: "Wi-Fi 2.4GHz", freq: 2400, txPower: 20, rxSensitivity: -90, bandwidth: 54000, color: "#3498DB"},
  {name: "Wi-Fi 5GHz", freq: 5800, txPower: 20, rxSensitivity: -85, bandwidth: 300000, color: "#2980B9"},
  {name: "BLE (1 Mbps)", freq: 2400, txPower: 0, rxSensitivity: -96, bandwidth: 1000, color: "#27AE60"},
  {name: "BLE (125 kbps)", freq: 2400, txPower: 0, rxSensitivity: -103, bandwidth: 125, color: "#16A085"},
  {name: "Zigbee", freq: 2400, txPower: 0, rxSensitivity: -100, bandwidth: 250, color: "#2ECC71"},
  {name: "Z-Wave", freq: 868, txPower: 0, rxSensitivity: -104, bandwidth: 100, color: "#34495E"},
  {name: "Thread", freq: 2400, txPower: 0, rxSensitivity: -100, bandwidth: 250, color: "#9B59B6"},
  {name: "Custom", freq: 915, txPower: 14, rxSensitivity: -110, bandwidth: 100, color: "#7F8C8D"}
]

viewof selectedProtocol = Inputs.select(protocols, {
  label: "Protocol:",
  format: p => p.name
})

73.4 Link Budget Parameters

Show code

viewof txPower = Inputs.range([-10, 30], {
  label: "TX Power (dBm):",
  step: 1,
  value: selectedProtocol.txPower
})

viewof txAntennaGain = Inputs.range([0, 10], {
  label: "TX Antenna Gain (dBi):",
  step: 0.5,
  value: 2
})

viewof rxAntennaGain = Inputs.range([0, 10], {
  label: "RX Antenna Gain (dBi):",
  step: 0.5,
  value: 2
})

viewof rxSensitivity = Inputs.range([-150, -70], {
  label: "RX Sensitivity (dBm):",
  step: 1,
  value: selectedProtocol.rxSensitivity
})

viewof frequency = Inputs.range([100, 6000], {
  label: "Frequency (MHz):",
  step: 1,
  value: selectedProtocol.freq
})

viewof fadeMargin = Inputs.range([0, 30], {
  label: "Fade Margin (dB):",
  step: 1,
  value: 10
})

73.5 Environment Selection

Show code

environments = [
  {name: "Free Space (LOS)", n: 2.0, description: "Clear line of sight, no obstacles"},
  {name: "Rural/Open Area", n: 2.5, description: "Minimal obstacles, some vegetation"},
  {name: "Suburban", n: 3.0, description: "Houses, trees, moderate obstacles"},
  {name: "Urban (Outdoor)", n: 3.5, description: "Buildings, streets, significant obstacles"},
  {name: "Urban (Dense)", n: 4.0, description: "City center, many tall buildings"},
  {name: "Indoor (Open Office)", n: 2.5, description: "Large open spaces, cubicles"},
  {name: "Indoor (Walls)", n: 3.5, description: "Multiple walls, typical building"},
  {name: "Indoor (Dense)", n: 4.5, description: "Many walls, metal structures"},
  {name: "Industrial", n: 4.0, description: "Factory, metal equipment, interference"}
]

viewof selectedEnvironment = Inputs.select(environments, {
  label: "Environment:",
  format: e => e.name
})

Show code

html`
<div style="background: #E8F4FD; padding: 10px 15px; border-radius: 6px; margin: 10px 0;">
  <strong>Environment:</strong> ${selectedEnvironment.description}<br>
  <strong>Path Loss Exponent (n):</strong> ${selectedEnvironment.n}
</div>
`

73.6 Range Calculation Results

Show code

linkBudget = {
  const eirp = txPower + txAntennaGain;
  const totalGain = txAntennaGain + rxAntennaGain;
  const allowedPathLoss = txPower + totalGain - rxSensitivity - fadeMargin;

  // Free space path loss at 1 meter reference
  const fspl1m = 20 * Math.log10(frequency) + 20 * Math.log10(1) - 147.55;

  // Calculate maximum range using log-distance path loss model
  // Path Loss = FSPL(1m) + 10 * n * log10(d)
  // Solving for d: d = 10^((AllowedPathLoss - FSPL(1m)) / (10 * n))
  const n = selectedEnvironment.n;
  const maxRangeMeters = Math.pow(10, (allowedPathLoss - fspl1m) / (10 * n));

  // Calculate range at different reliability levels
  const range99 = maxRangeMeters * 0.7; // With fade margin
  const range95 = maxRangeMeters * 0.85;
  const range90 = maxRangeMeters;

  return {
    eirp: eirp,
    totalGain: totalGain,
    allowedPathLoss: allowedPathLoss,
    fspl1m: fspl1m,
    maxRange: maxRangeMeters,
    range99: range99,
    range95: range95,
    range90: range90,
    n: n
  };
}

// Format range for display
formatRange = (meters) => {
  if (meters >= 1000) {
    return (meters / 1000).toFixed(2) + " km";
  } else {
    return meters.toFixed(0) + " m";
  }
}

Show code

html`
<div style="background: linear-gradient(135deg, #E8F6F3 0%, #D5F4E6 100%);
            padding: 25px; border-radius: 12px; margin: 20px 0;">
  <h3 style="margin-top: 0; color: #16A085;">Estimated Range</h3>

  <div style="display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 20px;">
    <div style="background: white; padding: 20px; border-radius: 10px; text-align: center;">
      <div style="color: #666; font-size: 12px;">MAXIMUM RANGE</div>
      <div style="font-size: 32px; font-weight: bold; color: #E67E22;">
        ${formatRange(linkBudget.maxRange)}
      </div>
      <div style="font-size: 11px; color: #999;">90% reliability</div>
    </div>

    <div style="background: white; padding: 20px; border-radius: 10px; text-align: center;">
      <div style="color: #666; font-size: 12px;">RELIABLE RANGE</div>
      <div style="font-size: 32px; font-weight: bold; color: #27AE60;">
        ${formatRange(linkBudget.range99)}
      </div>
      <div style="font-size: 11px; color: #999;">99% reliability (recommended)</div>
    </div>

    <div style="background: white; padding: 20px; border-radius: 10px; text-align: center;">
      <div style="color: #666; font-size: 12px;">LINK BUDGET</div>
      <div style="font-size: 32px; font-weight: bold; color: #3498DB;">
        ${linkBudget.allowedPathLoss.toFixed(1)} dB
      </div>
      <div style="font-size: 11px; color: #999;">Available path loss</div>
    </div>
  </div>
</div>
`

73.7 Link Budget Breakdown

Show code

html`
<div style="background: #f8f9fa; padding: 20px; border-radius: 12px; margin: 20px 0;">
  <h4 style="margin-top: 0;">Link Budget Analysis</h4>

  <table style="width: 100%; border-collapse: collapse;">
    <tr style="border-bottom: 1px solid #ddd;">
      <td style="padding: 10px;"><strong>TX Power</strong></td>
      <td style="padding: 10px; text-align: right; color: #27AE60;">+${txPower} dBm</td>
    </tr>
    <tr style="border-bottom: 1px solid #ddd;">
      <td style="padding: 10px;"><strong>TX Antenna Gain</strong></td>
      <td style="padding: 10px; text-align: right; color: #27AE60;">+${txAntennaGain} dBi</td>
    </tr>
    <tr style="border-bottom: 1px solid #ddd;">
      <td style="padding: 10px;"><strong>EIRP</strong> (Effective Radiated Power)</td>
      <td style="padding: 10px; text-align: right; font-weight: bold;">${linkBudget.eirp} dBm</td>
    </tr>
    <tr style="border-bottom: 1px solid #ddd;">
      <td style="padding: 10px;"><strong>RX Antenna Gain</strong></td>
      <td style="padding: 10px; text-align: right; color: #27AE60;">+${rxAntennaGain} dBi</td>
    </tr>
    <tr style="border-bottom: 1px solid #ddd;">
      <td style="padding: 10px;"><strong>RX Sensitivity</strong></td>
      <td style="padding: 10px; text-align: right; color: #2C3E50;">${rxSensitivity} dBm</td>
    </tr>
    <tr style="border-bottom: 1px solid #ddd;">
      <td style="padding: 10px;"><strong>Fade Margin</strong></td>
      <td style="padding: 10px; text-align: right; color: #E74C3C;">-${fadeMargin} dB</td>
    </tr>
    <tr style="background: #E8F6F3;">
      <td style="padding: 10px;"><strong>Available Path Loss</strong></td>
      <td style="padding: 10px; text-align: right; font-weight: bold; color: #16A085;">
        ${linkBudget.allowedPathLoss.toFixed(1)} dB
      </td>
    </tr>
  </table>

  <div style="margin-top: 15px; padding: 10px; background: #FEF5E7; border-radius: 6px;">
    <strong>Path Loss Model:</strong> PL(d) = ${linkBudget.fspl1m.toFixed(1)} + ${(10 * linkBudget.n).toFixed(0)} × log₁₀(d)
    <br><small>where d is distance in meters, using path loss exponent n = ${linkBudget.n}</small>
  </div>
</div>
`

73.8 Protocol Comparison

Compare range across different protocols in your selected environment:

Show code

protocolComparison = {
  const n = selectedEnvironment.n;

  return protocols.filter(p => p.name !== "Custom").map(p => {
    const totalGain = 4; // Assume 2 dBi each side
    const margin = 10;
    const allowedPL = p.txPower + totalGain - p.rxSensitivity - margin;
    const fspl1m = 20 * Math.log10(p.freq) - 147.55;
    const range = Math.pow(10, (allowedPL - fspl1m) / (10 * n));

    return {
      name: p.name,
      range: range,
      color: p.color,
      bandwidth: p.bandwidth
    };
  }).sort((a, b) => b.range - a.range);
}

Show code

html`
<div style="background: #f8f9fa; padding: 20px; border-radius: 12px;">
  <h4 style="margin-top: 0;">Range Comparison (${selectedEnvironment.name})</h4>

  ${protocolComparison.map((p, i) => {
    const maxRange = Math.max(...protocolComparison.map(x => x.range));
    const widthPercent = (p.range / maxRange) * 100;

    return html`
      <div style="margin-bottom: 12px;">
        <div style="display: flex; justify-content: space-between; margin-bottom: 4px;">
          <span style="font-weight: bold; color: ${p.color};">${p.name}</span>
          <span>${formatRange(p.range)}</span>
        </div>
        <div style="background: #E5E5E5; height: 20px; border-radius: 10px; overflow: hidden;">
          <div style="background: ${p.color}; height: 100%; width: ${widthPercent}%;"></div>
        </div>
      </div>
    `;
  })}

  <div style="margin-top: 15px; font-size: 12px; color: #666;">
    * Assumes 2 dBi antennas, 10 dB fade margin, standard TX power for each protocol
  </div>
</div>
`

73.9 Design Recommendations

Show code

recommendations = {
  const recs = [];

  if (linkBudget.maxRange < 100) {
    recs.push({type: "warning", text: "Short range - consider higher TX power or better antennas"});
  }

  if (fadeMargin < 6) {
    recs.push({type: "warning", text: "Low fade margin - link may be unreliable in varying conditions"});
  }

  if (fadeMargin > 20) {
    recs.push({type: "info", text: "High fade margin - you may be able to reduce TX power to save battery"});
  }

  if (selectedEnvironment.n >= 4) {
    recs.push({type: "warning", text: "Challenging environment - consider additional gateways or repeaters"});
  }

  if (frequency > 2000 && selectedEnvironment.name.includes("Indoor")) {
    recs.push({type: "info", text: "High frequency indoors - expect significant wall attenuation"});
  }

  if (linkBudget.allowedPathLoss > 150) {
    recs.push({type: "success", text: "Excellent link budget - should provide reliable long-range coverage"});
  }

  if (recs.length === 0) {
    recs.push({type: "success", text: "Link budget looks reasonable for typical deployments"});
  }

  return recs;
}

html`
<div style="margin: 20px 0;">
  <h4>Design Recommendations</h4>
  ${recommendations.map(r => html`
    <div style="background: ${r.type === 'warning' ? '#FEF5E7' : r.type === 'success' ? '#D5F4E6' : '#E8F4FD'};
                padding: 12px 15px; border-radius: 8px; margin-bottom: 10px;
                border-left: 4px solid ${r.type === 'warning' ? '#E67E22' : r.type === 'success' ? '#27AE60' : '#3498DB'};">
      ${r.type === 'warning' ? '⚠️' : r.type === 'success' ? '✓' : 'ℹ️'} ${r.text}
    </div>
  `)}
</div>
`

73.10 Knowledge Check

Question 1

You double the distance between transmitter and receiver. How much does path loss increase in free space (n=2)?

3 dB
6 dB
10 dB
20 dB

Answer

B) 6 dB - Path loss increases by 20×log₁₀(2) = 6 dB when distance doubles in free space. This is the “inverse square law” - doubling distance quarters the received power.

Question 2

LoRa at SF12 has -137 dBm sensitivity while Wi-Fi has -90 dBm. What does this mean for range?

Wi-Fi has longer range
LoRa has approximately 47 dB more link budget
They have the same range
It depends on TX power only

Answer

B) LoRa has approximately 47 dB more link budget - The difference in sensitivity (-137 vs -90 = 47 dB) directly translates to link budget advantage. This 47 dB allows LoRa to work at much greater distances despite similar TX power.

Question 3

Why is fade margin important in link budget calculations?

To make the math easier
To account for signal variations due to movement, weather, and multipath
To increase battery life
To reduce interference

Answer

B) To account for signal variations due to movement, weather, and multipath - Real-world signals fluctuate due to many factors. Fade margin (typically 10-20 dB) ensures the link remains reliable even when conditions temporarily worsen.

73.1 Wireless Range Calculator

73.2 Quick Start: Deployment Scenarios

73.3 Protocol Selection

73.4 Link Budget Parameters

73.5 Environment Selection

73.6 Range Calculation Results

73.7 Link Budget Breakdown

73.8 Protocol Comparison

73.9 Design Recommendations

73.10 Knowledge Check

73.11 Related Resources