ASLبشمهندس عسل

RF chain

حاسبة مسار RF وكثافة القدرة والاستقبال

Follow transmitted power through spreading and receive aperture.

المحتوى التفصيلي متاح بالإنجليزية، بينما الحسابات والوحدات والنتائج تعمل بنفس المحرك الهندسي.

Given / choose the units

Diagrams update as you edit. Run Calculate to refresh numerical results.

أدخل قيم التصميم ثم شغّل الحساب لمراجعة النتائج.

Swipe the diagram sideways to see the full view. With a keyboard, focus the diagram and use the arrow keys.

Understand the system

Radiated power and spreading

EIRP is transmitter power times antenna gain toward the receiver, after feeder losses. PFD is watts per square metre at a specified range. Doubling range spreads the same energy over four times the area, reducing PFD by 6.02 dB.

EIRP=PtGt/Lt,S=EIRP4πd2EIRP=P_tG_t/L_t,\quad S=\frac{EIRP}{4\pi d^2}

P_t: W; G_t: linear gain; L_t ≥ 1: linear feeder loss; d: m; S: W/m².

EIRP is directional equivalent power, not total physical RF output.

Source: week 3/reference.pdf · PDF page 74

Common mistakes

  • 92.44 requires km and GHz; 32.44 requires km and MHz.
  • PFD and received power have different units.
  • Do not include antenna gain twice after using EIRP.
Formula reference and symbol definitions

EIRP

EIRP=PtGt/LtEIRP=P_tG_t/L_t

P_t: W; G_t,L_t: linear

Gain toward receiver; feeder loss ≥ 1.

Example: For Pₜ = 10 W, Gₜ = 100 and Lₜ = 2, EIRP = 10 × 100/2 = 500 W ≈ 26.99 dBW.

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Power flux density

S=EIRP/(4πd2)S=EIRP/(4\pi d^2)

S: W/m²; d: m

Far-field free space.

Example: For EIRP = 1000 W and d = 10000 m, S = 1000/(4π × 10000²) ≈ 7.958 × 10⁻⁷ W/m².

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Free-space path loss

LFS=(4πdf/c)2L_{FS}=(4\pi df/c)^2

d: m; f: Hz; c: m/s; L: linear

Isotropic antenna references.

Example: At 6 GHz over 10 km, λ = 0.05 m and L = (4π × 10000/0.05)² ≈ 6.317 × 10¹², or 128.00 dB.

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FSPL shortcut

LFS,dB≈92.44+20log⁡10dkm+20log⁡10fGHzL_{FS,dB}\approx92.44+20\log_{10}d_{km}+20\log_{10}f_{GHz}

d: km; f: GHz

Course rounded c; free space.

Example: At 10 km and 6 GHz, L ≈ 92.44 + 20 log₁₀(10) + 20 log₁₀(6) = 128.00 dB.

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Friis received power

Pr=PtGtGr(λ/(4πd))2/LP_r=P_tG_tG_r(\lambda/(4\pi d))^2/L

P: W; gains/loss: linear; lengths: m

Matched far-field link.

Example: For 10 W, unity antenna gains, λ = 0.05 m and d = 10 km, Pᵣ = 10(0.05/(4π × 10000))² ≈ 1.583 × 10⁻¹² W.

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PFD received power

Pr=SAe/LP_r=SA_e/L

S: W/m²; A_e: m²; L: linear

Aperture and flux at same plane.

Example: For S = 10⁻⁹ W/m², Aₑ = 2 m² and L = 2, Pᵣ = 10⁻⁹ × 2/2 = 10⁻⁹ W = −90 dBW.

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Continue the signal path

Antenna Gain & Aperture Calculator →Noise, Noise Figure and G/T Calculator →Satellite Link Budget Calculator →

Design guide

Use the result with engineering context

Technical content reviewed

When this tool is useful

  • Calculating inverse square law with engineering models
  • Calculating eirp with engineering models
  • Calculating pfd with engineering models

What the result includes

  • Follow transmitted power through spreading and receive aperture.
  • Explanations, assumptions and links to related satellite calculators

What the model does not guarantee

  • Analytical engineering models do not replace measurements or a mission-specific design review.
  • Spectrum permissions, launch operations and real satellite tracking are outside these calculators.

Worked approach

Inverse square law

FSPL describes geometric spreading between ideal isotropic antenna references. At 10 km and 6 GHz it is approximately 128.0 dB. For d in km and f in GHz, use the 92.44 convenience constant; the fundamental equation uses consistent SI units.

Common decisions

Questions engineers ask

Which topics does RF Path, PFD and Received Power Calculator cover?

Inverse square law; EIRP; PFD; FSPL; Friis received power; Losses.

How should I check my work in RF Path, PFD and Received Power Calculator?

Read the stated assumptions and source references, check units and independently repeat a worked example before relying on the result.

Does RF Path, PFD and Received Power Calculator operate real satellite equipment?

No. This is a browser-based educational resource. It does not transmit RF signals, command spacecraft or certify a working link.

Related build evidence

Related embedded-system engineering

Aqua Sync is a separate connected-device project, not evidence of a satellite deployment.

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