RF & Wireless
RF circuit design, antenna theory, transmission lines, microwave components, and RF system architecture.
320 topics · 0 with articles
Intern Engineer· 80
- 2.5D EM Simulation: Momentum (ADS), Sonnet Em
- 3D EM Simulation: Ansys HFSS, CST Studio, Sonnet
- Ampere-Maxwell Law: ∇×H = J + ∂D/∂t
- Atmospheric Attenuation: O₂ (60 GHz), H₂O (22 GHz)
- Boundary Conditions at Dielectric Interface
- Channel Coherence Bandwidth: Bc ≈ 1/(5·τrms)
- Channel Coherence Time: Tc ≈ 0.423/fD
- Characteristic Impedance: Z0 = √(L/C) (Lossless)
- Circuit-EM Co-Simulation: Port Extraction and Integration
- Circular Waveguide: TE11, TM01 Dominant Mode
- Coaxial Line: TEM Mode, Cutoff Frequency, Attenuation
- Connector Types: SMA, N, 2.92mm, 1.85mm, 1.0mm (110 GHz)
- Constitutive Relations: D = εE, B = µH, J = σE
- Coplanar Waveguide (CPW): Ground on Same Layer
- De-Embedding: Fixture Removal from VNA Measurement
- Differential S-Parameters: Mixed-Mode SCC, SDD, SCD, SDC
- Diffraction: Knife-Edge Loss, Fresnel Zone Clearance
- Doppler Shift: fd = v·fc/c·cos(θ)
- Faraday's Law of Induction: ∇×E = -∂B/∂t
- Free-Space Path Loss: FSPL = (4πd/λ)²
- Fresnel Coefficients: Reflection and Transmission
- Friis Transmission Equation: Pr/Pt = Gt·Gr·(λ/4πd)²
- Gauss's Law for Electric Field: ∇·D = ρv
- Gauss's Law for Magnetic Field: ∇·B = 0
- Ground Reflection: Two-Ray Model (d² Dependence)
- Half-Wave Section: Impedance Repeating Property
- Impedance Matching with Smith Chart: L, π, T Networks
- Indoor Propagation: ITU-R P.1238, Partition Loss
- Insertion Loss: IL = -20log|S21| (dB)
- Ionospheric Effects: Faraday Rotation, TEC, HF Propagation
- Link Budget: EIRP, Path Loss, Sensitivity, Margin
- MIMO Channel: H Matrix, Spatial Multiplexing Capacity
- Mason's Signal Flow Graph: Gain Formula
- Massive MIMO: Large Antenna Arrays, Beamforming Gain
- Maximum Stable Gain (MSG) and Maximum Available Gain (MAG)
- Maxwell's Equations: Integral and Differential Forms
- Microstrip Line: Width vs. Z0, Effective εr, Losses
- Multipath Propagation: Constructive/Destructive Fading
- Noise Figure from S-Parameters: Friis Formula
- On-Wafer Probing: GSG Probe, Probe Station Setup
- Open-Circuit and Short-Circuit Stubs for Matching
- Path Loss Models: Free-Space, Log-Distance, Okumura-Hata
- Phase Constant β and Wavelength λ = 2π/β
- Plane Wave Propagation: Phasor Form and Complex k
- Power Flow: Poynting Vector S = E × H
- Propagation Constant: γ = α + jβ
- Propagation in Lossy Media: Attenuation Constant α
- Quantum Communication: Photon Entanglement and Channels
- Quarter-Wave Transformer: Impedance Inversion
- Rain Attenuation: ITU-R P.838 Model
- Rayleigh Fading: PDF, CDF, Doppler Spread
- Reconfigurable Intelligent Surface (RIS): Phase Shift
- Rectangular Waveguide: TE10 Mode, Cutoff fc = c/(2a)
- Reflection Coefficient: Γ = (ZL - Z0)/(ZL + Z0)
- Return Loss: RL = -20log|S11| (dB)
- Rician Fading: K-Factor and LOS Component
- S-Parameter Matrix: Incident and Reflected Waves
- S-Parameter to Z, Y, H Parameter Conversion
- S-Parameters Definition: S11, S21, S12, S22
- Short-Open-Load-Through (SOLT): ISS Calibration Standards
- Skin Depth: δ = 1/√(πfµσ) in Conductors
- Smith Chart Navigation: Move Clockwise (Toward Load)
- Smith Chart: Reflection Coefficient Plane
- Snell's Law of Refraction for EM Waves
- Stability Analysis: K-Factor (Rollett), B1 Criterion
- Standing Waves: Nodes and Antinodes of V and I
- Stripline: Buried Conductor, No Radiation, Shielded
- T-Matrix (ABCD Matrix) for Cascaded Networks
- Telegrapher's Equations: Voltage and Current Waves
- Terahertz (THz) Propagation: Molecular Absorption
- Time-Domain Reflectometry (TDR): Impedance Profile
- Total Internal Reflection and Critical Angle
- Transducer Power Gain, Available Gain, Operating Gain
- Transmission Line Model: Distributed L, C, R, G Parameters
- Troposcatter: Long-Range Beyond-LOS Communication
- Urban Ray Tracing: Buildings, Reflection, Diffraction
- VNA Calibration: SOLT, TRL, SOLR, LRM Methods
- Voltage Standing Wave Ratio: VSWR = (1+|Γ|)/(1-|Γ|)
- Wave Equation Derivation from Maxwell's Equations
- Wave Polarization: Linear, Circular, Elliptical
Junior Engineer· 40
- Branch-Line Coupler: 90° Hybrid, I/Q Split
- Cavity Filter: High Q, High Power, Low Insertion Loss
- Class E PA: ZVS Switching for >90% Efficiency
- Class F PA: Harmonic Tuning for High Efficiency
- Colpitts VCO: CMOS and Bipolar Implementation
- Digital Pre-Distortion (DPD): Memory Polynomial Model
- Doherty PA: Peak and Carrier Amplifier, Back-Off Efficiency
- Envelope Tracking (ET) Power Supply for PA Efficiency
- FBAR/BAW Filter: Bulk Acoustic Wave for Mobile RF
- GaN MMIC PA: Layout, Via Holes, Air-Bridge Connections
- Gilbert Cell CMOS Active Mixer
- Image Reject Mixer: Hartley and Weaver Architectures
- LNA Cascode: High Gain, Improved Isolation
- LNA Input Matching: Conjugate vs. Noise Optimal
- LNA Multi-Stage: Cascaded NF (Friis Formula Application)
- LNA Noise Matching vs. Simultaneous Noise and Power Match
- LNA Topology: Common-Source with Inductive Degeneration
- Lange Coupler: Tight Coupling at mmWave Frequencies
- Limiter / Protector: PIN Diode for Receiver Protection
- Low-Noise Amplifier (LNA): Noise Figure, Gain, Stability
- MMIC Design Flow: Process Selection, Layout, EM Verification
- PA Classes A, AB, B, C: Conduction Angle, Efficiency
- PA Load-Pull Measurement: Optimal ZL for Pout, PAE
- PA Stability: Conditional Stability, Stabilization Network
- Phase Shifter: Analog (Varactor), Digital (SPDT Switch)
- Power Amplifier (PA): Output Power, PAE, Gain
- Push-Push VCO: Second Harmonic Output at 2f0
- RF Attenuator: Pi and T Pad, Absorptive vs. Reflective
- RF Circulator and Isolator: Ferrite-Based Non-Reciprocal
- RF Filter Design: Coupled-Line BPF, Hairpin, Combline
- RF Mixer: Conversion Gain, NF, IIP2, IIP3, LO Isolation
- RF Switch: PIN Diode, FET Switch, MEMS Switch
- RF Transistor Technologies: GaAs pHEMT, GaN HEMT, SiGe HBT, RF CMOS
- Rat-Race Coupler: 180° Hybrid, Balanced Mixer Input
- SAW Filter: Surface Acoustic Wave for Sub-6 GHz
- Single-Balanced and Double-Balanced Mixer Topologies
- Sub-Harmonic Mixer for mmWave Applications
- VCO Design: LC Tank, Tuning Range, Phase Noise
- VCO FOM (Figure of Merit): Phase Noise, Power, Frequency
- Wilkinson Divider: In-Phase Split, Isolation Between Ports
Middle Engineer· 80
- 5G NR Sub-6 GHz: FR1, Numerology (µ=0,1,2), Slot Structure
- 5G NR mmWave (FR2): 24–52 GHz, Beamforming, Beam Management
- 5G NSA and SA Architecture: 4G Core vs. 5G Core (5GC)
- 5G Network Slicing: eMBB, URLLC, mMTC Use Cases
- 5G Sub-6 GHz Antenna: 4×4, 8×8 MIMO Integration
- 5G mmWave Antenna Module: AiP (Antenna-in-Package)
- 6G Vision: Sub-THz, AI-Native Air Interface, RIS
- AESA (Active Electronically Scanned Array): T/R Module
- Adaptive Beamforming: LMS, MVDR, LCMV Algorithms
- Antenna Fundamental Parameters: Gain, Directivity, Efficiency
- Antenna Measurement: Far-Field Chamber, Near-Field Scanner
- Antenna Polarization: LP, CP (RHCP/LHCP), Cross-Pol
- Antenna Simulation: HFSS, CST, FEKO, IE3D
- Array Factor: Pattern Multiplication with Element Pattern
- BLE 5.x: Extended Advertising, Periodic Advertising, PAST
- BLE Audio (LE Audio): ISO, LC3 Codec, Auracast Broadcast
- BLE Mesh: Flooding, Managed Flood, Provisioning
- Bluetooth Classic: BR (1 Mbps), EDR (2/3 Mbps) PHY
- Bluetooth Low Energy (BLE): LE 1M, LE 2M, LE Coded PHY
- Bow-Tie Antenna: Wideband, Self-Complementary
- Cellular IoT: NB-IoT, LTE-M, Cat-1 bis Comparison
- Cognitive Radio: Dynamic Spectrum Access, DSA
- Compact Antenna Test Range (CATR) for mmWave
- DASH7: ISO/IEC 18000-7, Active RFID Protocol
- DECT-2020 NR: Next-Gen DECT for IIoT and Smart Home
- Digital Beamforming (DBF): ADC per Element, Flexibility
- Diversity Techniques: Space, Polarization, Pattern, Frequency
- Effective Aperture Ae and Gain Relationship: Ae = Gλ²/4π
- Effective Isotropic Radiated Power (EIRP) Calculation
- GNSS Interference: Jamming, Spoofing, Meaconing
- GPS/GNSS: L1, L2, L5 Bands, Pseudorange, NMEA
- Grating Lobes: Condition d > λ/2 at Scan Angle
- HaLow (802.11ah): 900 MHz, Long Range, Low Power
- Half-Wave Dipole: Radiation Resistance 73 Ω, Gain 2.15 dBi
- Helical Antenna: Axial Mode, Circular Polarization
- Horn Antenna: Pyramidal, Conical, Gain vs. Aperture
- IEEE 802.11 Wi-Fi Standards: a/b/g/n/ac/ax/be Evolution
- LEO Satellite Direct-to-Device: Starlink, AST SpaceMobile
- LTE-M (eMTC): Cat-M1, VoLTE, Higher Data Rate vs. NB-IoT
- LoRa: Chirp Spread Spectrum (CSS) Modulation
- LoRaWAN: OTAA/ABP Join, Class A/B/C, ADR
- Log-Periodic Dipole Array (LPDA): Wideband Coverage
- Loop Antenna: Small Loop (Magnetic Dipole) Properties
- MIMO Antenna: Isolation, Envelope Correlation, Efficiency
- Massive MIMO Antenna: >64 Elements, Hybrid Beamforming
- Matter (CHIP): Application Layer over Thread/Wi-Fi/Ethernet
- Metamaterial Antenna: CRLH, High-Impedance Surface (HIS)
- Microstrip Patch Antenna: TM10 Mode, Fringing Fields
- Monopole over Ground Plane: Image Theory, Gain 5.15 dBi
- Mutual Coupling in Arrays: Active Element Pattern
- NB-IoT (LTE-M-NB): Coverage Enhancement, PSM, eDRX
- OTA (Over-The-Air) Testing: TRP, TIS, EIS, ERP Measurement
- Parabolic Reflector: Focal Length, Aperture Efficiency
- Patch Antenna Design: W, L for Resonance at f0
- Patch Antenna Feed: Coaxial Probe, Microstrip Edge, Inset
- Patch Array: Array Factor, Mutual Coupling Effects
- Patch Bandwidth: Q Factor, Return Loss vs. Bandwidth
- Phased Array: Phase Shifter Control, Steering Angle
- Polarization Mismatch Loss: PLF = cos²(ψ)
- RF Regulatory: FCC, ETSI, ISED, SRRC Key Requirements
- RTK-GPS: Carrier-Phase Differential, cm-Level Accuracy
- Radiation Pattern: Main Lobe, Side Lobes, Back Lobe, HPBW
- Reconfigurable Antenna: Frequency, Pattern, Polarization
- Satellite IoT: Swarm, Kinéis, Iridium 9603, Astrocast
- Sigfox: UNB (Ultra-Narrowband) Uplink/Downlink
- Slot Antenna: Complementary to Dipole (Babinet's Principle)
- Spectrum Sharing: LSA, CBRS (3.5 GHz) Band Framework
- Thread: IPv6 over 802.15.4, Mesh Routing (RPL)
- UWB (IEEE 802.15.4z): Precision Ranging, Time-of-Flight
- Vivaldi Antenna: Tapered Slot, UWB (3.1–10.6 GHz)
- Wi-Fi 6 (802.11ax): OFDMA, MU-MIMO, BSS Coloring, TWT
- Wi-Fi 6E: 6 GHz Band, Channel Plan, Regulatory
- Wi-Fi 7 (802.11be): 320 MHz, 4K-QAM, Multi-Link Operation
- Wi-Fi MAC: CSMA/CA, EDCA, Block ACK, AMPDU
- Wi-Fi Physical Layer: OFDM Subcarrier Spacing, CP, Pilots
- Wi-SUN FAN: Mesh for Smart Grid and Utility IoT
- WiMAX / IEEE 802.16: OFDMA, QoS for Broadband
- Yagi-Uda Antenna: Driven, Reflector, Director Elements
- Zigbee / IEEE 802.15.4: PHY, MAC, Network, App Layer
- mioty: Telegram Splitting Multiple Access (TSMA)
Senior Engineer· 80
- 5G NR RF Conformance: 3GPP TS 38.101 Test Cases
- ADC in Receiver: ENOB, SFDR, Sampling Rate Requirements
- Antenna Pattern Measurement: Azimuth, Elevation Cuts
- Automated RF Test: LabVIEW, MATLAB, PyVISA, SCPI Commands
- Automatic Gain Control (AGC): Loop, Attack, Release Time
- BLE/Wi-Fi Conformance Test: Bluetooth Spec SIG, Wi-Fi Alliance
- Calibration Uncertainty Budget: ISO/IEC 17025 Approach
- Carrier Aggregation: Intra-Band, Inter-Band, CA Combiner
- Cascade IIP3: System Linearity from Gain and IIP3 Budget
- Channel Estimation: LS, MMSE, Pilot Patterns
- Channel Filter: SAW/BAW BPF, Polyphase Filter
- Conducted Emission: LISN, EN 55032 Class B Limit
- Conducted Susceptibility: IEC 61000-4-6 Bulk Current Injection
- Digital IF and Direct RF Sampling Architecture
- Directional Coupler: Sampling Incident/Reflected Power
- Dynamic Range: Spurious-Free DR, BDR, Linear DR
- ESD Immunity: IEC 61000-4-2 Contact and Air Discharge
- Envelope Detector for AM Demodulation
- Equalization: ZF, MMSE, DFE for Multipath Channels
- Error Vector Magnitude (EVM): Measurement and Limits
- Eye Diagram for High-Speed Digital and RF Signal
- FM Discriminator: Phase-Locked Loop Demodulation
- Fractional-N PLL: Sigma-Delta Divider, Fractional Spurs
- Full-Duplex (Self-Interference Cancellation): Analog + Digital
- GNU Radio: Open-Source SDR Processing Framework
- Gain Measurement: Comparison Method, Absolute Method
- Group Delay Measurement: Phase vs. Frequency Derivative
- Homodyne (Zero-IF / Direct Conversion) Receiver
- I/Q Demodulator: Carrier Recovery, Costas Loop
- I/Q Modulator: IQ Imbalance, Phase and Gain Error
- IM3 Measurement: Two-Tone Test, IIP3 Extrapolation
- Image Frequency and Image Reject Filter Requirements
- Integer-N PLL: Reference Spurs, Phase Noise
- Intermodulation Distortion: IIP3, OIP3, IP2 Definitions
- Intermodulation Test: Two-Tone Generator, Bandpass Filter
- Jitter Measurement: RJ, DJ, TJ Components
- Load Pull System: Tuner-Based and Active Load-Pull
- Low-IF Receiver: Compromise Between Superheterodyne and ZIF
- MIMO Transceiver: Multiple TX/RX Chains, Calibration
- Noise Figure Analyzer: Y-Factor Method, Cold-Source Method
- Noise Source: ENR (Excess Noise Ratio) Calibration
- OFDM Synchronization: Timing Offset, Carrier Frequency Offset
- OTA Test Methods: CATR, Spherical NFS, Cylindrical NFS
- OTA Testing: TRP (Total Radiated Power), TIS Measurement
- PA Characterization: P1dB, Psat, OIP3, PAE Measurement
- PLL Frequency Synthesizer: Reference, VCO, Divider
- Phase Noise Analyzer: Cross-Correlation Method
- Phase Noise Measurement: Carrier Offset, Integrated Phase Noise
- Phased Array Beamforming RFIC: 5G NR FR2 mmWave
- Power Sensor and Power Meter: Calibration, Accuracy
- RAKE Receiver: Multipath Diversity Combining (3G CDMA)
- RF FEM for 5G Sub-6 GHz: PAM4G3 Architecture
- RF Front-End Module (FEM): PA + LNA + Switch + Filter
- RF Immunity: IEC 61000-4-3 Radiated Susceptibility
- RF SoC (e.g., nRF52, CC2652, QCA4020): Full Stack
- RFIC for 5G: Qualcomm QTM535, Mediatek T800, Samsung RFIC
- Radiated Emission: OATS or Semi-Anechoic Chamber
- Receiver Blocking: Large Out-of-Band Signal Desensitization
- Receiver Noise Figure: System NF from Friis Formula
- SAR Measurement: IEC 62209-1, IEEE 1528 Protocol
- SDR (Software-Defined Radio): ADC/DAC + FPGA/DSP
- Sensitivity: MDS = -174 + NF + 10log(BW) + SNRmin
- Signal Generator: CW, Modulated, Frequency/Phase/AM Control
- Spectrum Analyzer Measurement: Power, Harmonics, Spurs
- Spectrum Analyzer: Architecture, RBW, VBW, Span, Reference
- Spurious Emission Measurement: CISPR, FCC Part 15
- Superheterodyne Receiver: IF Selection, Image Rejection
- TCXO and OCXO Reference Oscillator for Low Phase Noise
- TDD vs. FDD: Duplexer, Switch, Isolation Requirements
- Transceiver (TRx) IC: Integrated RF Front-End
- USRP / RTL-SDR / Ettus Hardware Platforms
- VNA Calibration: SOLT (Short-Open-Load-Through)
- VNA Calibration: TRL (Thru-Reflect-Line) for mmWave
- VNA Port Extension and De-Embedding Techniques
- VNA Time-Domain Mode: TDR for Impedance vs. Distance
- VSWR and Return Loss Measurement: VNA and Directional Bridge
- Vector Network Analyzer (VNA): Principle and Architecture
- Vector Signal Analyzer (VSA): EVM, Constellation Diagram
- Vector Signal Generator: IQ Modulation, Waveform Playback
- Zero-IF Challenges: DC Offset, I/Q Imbalance, Flicker Noise
Distinguished Engineer· 40
- 5G NR FR2: 24.25–52.6 GHz Band Plan and Channel Width
- 5G mmWave AiP (Antenna-in-Package): Flip-Chip + Antenna
- 60 GHz (802.11ad/ay): WiGig Multi-Gigabit WLAN
- 6G RF Technology Roadmap: Sub-THz, AI-Native, RIS
- 77 GHz Automotive Radar: FMCW, Range, Velocity, Angle
- 94 GHz W-Band: Security Imaging and SATCOM
- AI for RF Fingerprinting: Signal Authentication and ID
- AI-Driven Beamforming: ML-Based Beam Selection
- Automotive Radar MIMO: Virtual Array, Angular Resolution
- Beam Failure Recovery: BFR Procedure in 5G NR
- Beam Management in 5G NR: SSB, CSI-RS, Beam Sweeping
- BiCMOS SiGe: 130nm, 55nm for mmWave Front-End IC
- CMOS mmWave: 28nm, 16nm FinFET at 60 GHz
- Cognitive Radar: Environment Sensing, Adaptive Waveform
- D-Band (110–170 GHz): Backhaul, Sensing Applications
- FMCW Radar Signal Processing: Range-Doppler Map, CFAR
- GaN on SiC for mmWave PA: 28 GHz and 39 GHz
- Hybrid Beamforming: Phase Shifter + Digital Precoding
- InP HBT Technology: fT > 500 GHz for THz Circuits
- Joint Communication and Sensing (ISAC): 5G Radar
- LEO Satellite Downlink: Phased Array User Terminal
- On-Chip Antenna at mmWave: Efficiency, Substrate Modes
- Photonic-Assisted RF: Electro-Optic Modulator, MZM
- Point-to-Point Microwave Backhaul: E-Band 80 GHz Link
- Quantum RF Sensing: Rydberg Atom Electrometer
- RIS Phase Control: Digital Phase Shifter or Varactor
- Radar PCB Design: Substrate, Via, Launch, Feed Network
- Radio-over-Fiber (RoF): Fronthaul for Distributed Antenna
- Reconfigurable Intelligent Surface (RIS) / IRS: Passive Reflect
- Satellite Communication: Ku, Ka, V-Band VSAT System
- Spectrum Monitoring: Wideband Scanning Receiver Design
- THz (0.3–3 THz): Spectroscopy, Imaging, Communication
- THz Detector: Golay Cell, Pyroelectric, Hot-Electron Bolometer
- THz Source: Schottky Multiplier Chain, Resonant Tunnel Diode
- W-Band VNA: Waveguide Extender, 75–110 GHz Coverage
- Wafer-Level Packaging (WLP) for mmWave Module
- mmWave Beamforming: Analog, Digital, Hybrid Architectures
- mmWave Channel: High Path Loss, Oxygen Absorption at 60 GHz
- mmWave Frequency Bands: 24, 28, 39, 60, 77, 94, 140 GHz
- mmWave RFIC Measurement: Probe Station, GSG Probe