Worked RF safety survey and report

This capstone follows an assessment from scenario definition to report structure and review decisions. The fictional data demonstrate the calculations; the report shell shows where real project evidence belongs. They do not form a completed site assessment.

Next action: If you need a one-page memory jog before field work, start with 0. Quick reference.

1) At a glance (what you build)

You will produce:

• a scenario list (who/where/how long) with access classification
• a measurement plan (points/heights/time state + escalation triggers)
• a small dataset and the correct combining/averaging math
• an uncertainty statement that affects your compliance margin
• an audit-ready report with implementable controls + change-control triggers

2) The example scenario (illustrative)

Site type: multi-band rooftop telecom installation
Your task: confirm compliance at accessible locations and define controlled-area boundaries for occupational access.

Assumptions for the example (replace these in real work):

• Multiple RF services are present (multi-band, potentially multi-operator).
• Access includes both:
  • public/uncontrolled areas (building edge/adjacent accessible spaces), and
  • occupational/controlled areas (locked rooftop with trained staff).
• You will use a staged method: broadband mapping → selective confirmation → controls.

Primary workflow references in this course:

• “What metric applies?”: C. Near field vs far field + F. Power density and field strength
• “How do I do averaging?”: G. Time averaging
• “How do I choose instruments?”: O–R
• “How do I write it up?”: W. Compliance testing and reporting

3) Step-by-step workflow (with deliverables)

Step 1 — Establish the compliance basis (edition control)

Deliverable (one paragraph in your report):

• Jurisdiction/permit/contract basis
• Adopted framework family (ICNIRP-derived vs IEEE-derived vs other)
• Edition/revision used (and any national modifications)

Discipline rule: never write “ICNIRP compliant” or “IEEE compliant” without the edition and the context (public vs occupational/controlled).

Step 2 — Build the transmitter inventory (don’t skip co-location)

Deliverable (inventory table appendix):

• bands/services present
• max configured power/EIRP basis (configured vs measured vs contractual)
• antenna types and mounting geometry (height, azimuth, tilt)
• time behavior assumptions (duty/traffic, TDD, beam states)
• concurrency assumptions (who can transmit at the same time)

Step 3 — Define scenarios and classify access (per location)

Deliverable (scenario table):

• location name + photo/sketch
• who can access (public/tenants vs trained workers/contractors)
• access controls relied upon (locks, barriers, escort, permit-to-work)
• classification outcome (public/uncontrolled vs occupational/controlled)

If any access control or training is weak, treat it as public/uncontrolled until corrected.

Step 4 — Classify field region at candidate maxima (near vs far field)

Deliverable (one calculation per candidate maximum):

• frequency used for the region boundary check (conservative choice)
• antenna aperture size D used (arrays: full aperture)
• computed R_far and your measurement distance R
• conclusion: far field / radiating near field / reactive near field

If the point is plausibly near field, avoid “plane-wave conversion” shortcuts and plan scan-based sampling.

Step 5 — Choose the method and write the measurement plan (before you measure)

Deliverable (method section):

• phase 1: broadband mapping plan (where/how many points/heights)
• phase 2: selective confirmation plan (which bands, settings, dwell/averaging)
• time behavior definition (typical vs bounded worst-case)
• spatial plan (how maxima are searched; any spatial averaging definition)
• uncertainty approach and escalation triggers (“if within X dB of the limit…”)

Step 6 — Collect data (example dataset)

Below is an illustrative dataset showing the kind of structured evidence you want. Replace it with your real logs and instrument outputs.

6.1 Broadband mapping (hotspot finding)

Broadband RMS E-field mapping, 6 points along an access route at 1.5 m height:

Interpretation: P3 and P5 are candidates for selective follow-up; P6 is important because it’s near an uncontrolled/public-adjacent area.

6.2 Selective measurement at a candidate maximum

At P3, selective results are processed into RMS electric-field fractions rᵢ = Eᵢ/Lᵢ, each relative to its applicable band-specific field reference level for one chosen population and averaging definition. For this fictional exercise, assume the adopted rule requires the squared sum to be no greater than 1. The complete table and field-region conditions must also hold in a real assessment.

Example results (ratios are dimensionless):

The worked calculation below combines these fractions and applies the illustrative uncertainty. We use R for the square root of the squared sum: a field-equivalent fraction, not a fraction of health risk or of a single band’s limit. P3 is a candidate maximum, not an established site maximum; P5 and the other accessible locations still need confirmation.

Step 7 — Add uncertainty (so your margin means something)

Pick an uncertainty method that matches your organization’s quality requirements. A simple, defensible approach is:

• state dominant contributors (calibration/systematic; positioning/gradient; time variability; selective capture adequacy)
• express uncertainty as an expanded factor (e.g., ±dB or ±%)
• show how it changes the margin

In this example, use expanded uncertainty of ±3 dB on the field-amplitude scale (20 log ₁₀), equivalent to multiplying or dividing by about 1.41. The worked example applies the upper factor to R. This interval alone does not cover missed locations, bands or operating states; those omissions need separate evidence. Use the adopted decision rule rather than treating an expanded interval as an absolute guarantee.

Step 8 — Translate results into controls (and keep them true)

Your report is incomplete until it specifies controls that operators can actually implement and maintain.

Deliverables:

• boundary points tied to physical landmarks (not “5.3 m from antenna”)
• signage and access control that match public vs occupational classification
• procedures for work near antennas (permit-to-work, RF reduction/shutdown verification)
• change control triggers (reassess after upgrades, re-aim, new co-locators, access changes)

4) Partly populated report structure

Template use note: Use this as a model report shell. Replace each template field with project-specific values, adopted framework identifiers, and traceable method references.

This is a partly populated report structure, not a completed compliance determination. The supplied data support a calculation at P3 only. The remaining source, method, location and control evidence must be supplied before a site conclusion or boundary approval.

4.1 Executive summary (example)

Purpose: Evaluate RF exposure at Template field: site name or identifier at accessible locations and confirm compliance with Template field: adopted framework and edition reference levels, and define controlled-area boundaries for occupational access.

Method: A staged approach was used:

1. broadband mapping survey to identify candidate maxima, followed by
2. frequency-selective measurements at worst-case points to produce per-band exposure ratios and a combined exposure ratio using the adopted summation method.

Instrument chain, settings, averaging and geometry must be documented. The illustrative P3 calculation uses ±3 dB expanded field uncertainty; its basis and applicability must be substantiated.

Result: At P3, the supplied fractions give R ≈ 0.38, or 38% on the field-equivalent scale, with an illustrative upper value of about 0.53. Results for the other candidate maxima and accessible scenarios are not supplied.

Conclusion: The P3 example calculation is below its assumed criterion including the stated uncertainty treatment. It does not establish site-wide compliance or approve a controlled-area boundary. Complete the remaining assessments, verify the operating-state bounds and implement the documented controls before making that conclusion.

4.2 Scope and compliance basis (example)

• Jurisdiction / authority: Template field: authority name and permit context
• Framework adopted: Template field: framework family (ICNIRP-derived, IEEE-derived, or national basis)
• Edition / revision: Template field: exact edition or revision, including national modifications
• Environment classification: public/uncontrolled for Template field: listed areas, occupational/controlled for Template field: listed areas, with controls documented in Section 4.7.

4.3 Site description and inventory (example)

• Site type: rooftop telecom installation with Template field: number of antennas antennas and Template field: number of band groups band groups.
• Antenna geometry: heights, azimuths, tilts documented in Appendix A with photos and sketches.
• Operating state: measurements performed under Template field: typical or bounded worst-case conditions as documented; concurrency assumptions documented.

4.4 Methodology (example)

Broadband survey:

• quantity: RMS E-field over probe band
• heights: 1.5 m above roof surface; additional heights at Template field: additional measurement heights, if used
• points: P1–P6 (Appendix B map), with maxima-search strategy documented
• geometry control: probe on non-conductive pole; operator stand-back for final readings

Selective confirmation:

• per-band measurements at candidate maxima P3 and P5
• settings: Template field: RBW, VBW, detector mode, averaging, and integration method
• chain corrections: probe sensitivity/AF, cable loss, attenuation/preamps as documented
• outputs: per-band exposure fractions rᵢ and combined ratio R

Near/far-field handling:

• near-field plausibility checked using R_far ≈ 2D²/λ for relevant apertures and conservative frequency selection.
• where near-field behavior was plausible, the assessment relied on scan-based sampling and did not assume plane-wave conversions beyond what the method justified.

4.5 Results (example)

• Broadband mapping identified candidate maxima at P3 and P5.
• Selective confirmation at P3 produced per-band ratios r₁ = 0.32, r₂ = 0.18, r₃ = 0.09 and combined ratio R ≈ 0.38.
• Additional points: Template field: summary of remaining assessed locations

4.6 Uncertainty and limitations (example)

Dominant uncertainty contributors include:

• calibration/systematic uncertainty of the probe/chain
• positioning sensitivity due to spatial gradients near reflective structures
• time variability due to traffic, scheduling, and beam behavior
• selective capture adequacy for bursty/TDD signals

Margins are interpreted with conservative awareness of these contributors. Where results approach a decision threshold, the method escalation pathway in Section 4.8 applies.

4.7 Controls and implementation (example artifacts)

Boundary marking scheme (implementable):

• Mark controlled-area boundary points on the roof using fixed landmarks documented in the survey diagram (for example: parapet corner, equipment plinth, ladder base, roof hatch), with distances between landmarks shown on a diagram.
• Avoid boundaries defined only as “X meters from antenna,” unless physically marked and maintained.

Signage placement logic (minimum):

• Place signage at every entry point to controlled access (hatch/door/ladder).
• Place additional signs at boundary transitions along walk paths (where someone could accidentally enter a controlled zone).
• Assign ownership and inspection frequency (e.g., quarterly or after storms/works).

Permit-to-work (antenna-adjacent tasks):

1. Identify work location and active transmitters.
2. Decide required controls: boundary-only vs RF reduction/shutdown.
3. If RF reduction/shutdown is required: request, authorize, and verify status before entry.
4. Document verification and restore-to-service steps.
5. Stop-work criteria: signage missing, access route changed, unexpected high readings, or transmitter state uncertain.

Change control triggers (reassessment required):

• new radios/bands added or power increases
• antenna re-aim/tilt changes
• new co-locators or concurrency assumption changes
• physical changes that alter accessible distances/routes (new ladder, platform, handrail changes)
• access control changes (locks removed, roof becomes tenant-accessible)

4.8 Method escalation pathway (when you’re close to a threshold)

If the combined ratio is near 1.0 once uncertainty is considered:

1. verify no overload/compression and repeat with controlled geometry
2. expand spatial sampling around maxima (multiple heights and finer grid)
3. move from broadband to selective (or verify selective settings/capture adequacy)
4. refine the operating state to a bounded worst-case (documented)
5. if required by the framework, perform refined assessment against internal metrics (dosimetry/modeling)
6. implement engineering/administrative controls and re-verify

5) Pre-submission decision gate

Before treating a survey as ready for technical review, verify all five statements:

1. The adopted framework, edition, jurisdiction, population class, metric, and averaging rule are explicit.
2. The transmitter inventory and operating-state assumptions bound every credible contributor.
3. The sampling plan can find spatial maxima and distinguish broadband screening from selective attribution.
4. The decision uses an uncertainty-aware upper bound, not only the indicated reading.
5. Every relied-upon control has an owner, verification method, inspection cadence, and change trigger.

If any statement is false, the correct output is an action or limitation—not an unsupported compliance conclusion.

Worked example and checks

Mind stretchers

8) Report resources

For the full report structure and supporting records, use Compliance testing and reporting. The examples above show how to keep each decision tied to the evidence actually supplied.