The HP/Agilent 4815A RF Vector Impedance Meter measures complex impedance across 500 kHz to 108 MHz using synchronous sampling and direct phase detection. It delivers impedance magnitude from 10 Ω to 100 kΩ with ±4% full-scale accuracy and phase angle across 0° to 360° with frequency- and impedance-dependent accuracy. The instrument maintains constant test current via ALC circuitry, enabling direct impedance-to-voltage correlation and precise phase relationship detection between voltage and current waveforms.
Technical Specifications
Frequency Range: 500 kHz to 108 MHz in five bands: 500 kHz–1.5 MHz, 1.5–4.5 MHz, 4.5–14 MHz, 14–35 MHz, 35–108 MHz.
Impedance Magnitude: 10–100 kΩ across nine full-scale ranges (10, 30, 100, 300, 1k, 3k, 10k, 30k, 100k Ω). Accuracy: ±4% of full scale and ±2% of reading.
Phase Angle: 0°–360° on two ranges. Accuracy: ±(3° + f/30 MHz + Z/50 kΩ) degrees, dependent on frequency and impedance.
Oscillator Test Signal: Internal RF source 0.5–108 MHz; test current 12.6 µA at 10 Ω range, 4 µA on all other ranges. External RF source supported.
RF Monitor Output: 150 mV minimum into 50 Ω.
Measurement Technique: Synchronous sampling converts RF to 5 kHz IF. Unnormalized impedance measured at probe tip relative to ground. Constant-current ALC maintains impedance proportional to voltage; phase derived from voltage-current waveform relationship.
Measurement Terminals: Probe at end of 5 ft cable with BNC and Type N adapter provisions. Component mounting adapter available. Meter readings include residual probe impedance effects.
Calibration: Self-calibration in impedance parameters. Special frequency points 1.592 MHz and 15.92 MHz enable direct microhenry or microfarad readings. Magnitude accuracy ±2% of reading at these frequencies.
Outputs: DC voltages proportional to magnitude, phase, and frequency available at rear panel.
– Key Features
• Dual-range phase measurement across full 360° span
• Constant-current source via ALC for stable impedance correlation
• Nine impedance ranges spanning two decades
• Probe-tip measurement minimizes cable effects
• Self-calibrating with impedance-direct calibration points
– Typical Applications
• RF impedance matching and characterization
• Antenna design and tuning
• Microwave component impedance measurement
• Resonant frequency and Q-factor determination
– Compatibility & Integration
Rear-panel analog outputs (magnitude, phase, frequency) integrate with external recording and data acquisition equipment. Multi-coax probe connector on front panel; 5 ft cable with adapter options for BNC and Type N terminations.
