I. High-Precision, Wideband Structure Design (Suitable for DC-3GHz Calibration Requirements)

　　1. High-Precision Impedance Control Structure

　　Upgraded Core Materials and Processing:

　　The 99.99% high-purity oxygen-free copper inner conductor (diameter 2.0 ± 0.02mm) is paired with a 0.1% precision thin-film load resistor (temperature coefficient ±5ppm/°C). Laser trimming technology controls the 75Ω impedance deviation to ±0.5Ω (over the entire DC-3GHz band), far exceeding the ±1Ω accuracy standard of conventional terminators. The outer shell is made of gold-plated brass (plating thickness ≥ 5μm) and undergoes five-axis CNC machining to ensure an inner bore coaxiality of ≤0.01mm, preventing high-frequency signal reflections caused by structural eccentricity. Wideband Adaptive Design:

　　The internal PCB utilizes Rogers 4350B high-frequency substrate (dielectric constant 4.4 ± 0.04). The microstrip line features a tapered impedance transition structure (impedance gradient ≤ 0.5 Ω/mm from the 75 Ω load end to the connector end), eliminating impedance discontinuities within the DC-3 GHz frequency band. The terminator length is optimized to 45 mm, shortening the high-frequency signal transmission path and reducing the impact of parasitic inductance/capacitance on wideband performance (parasitic inductance ≤ 0.5 nH, parasitic capacitance ≤ 0.2 pF at 3 GHz).

　　2. Low-Reflection Sealed Structure

　　Reflection Suppression Design:

　　Both ends of the load resistor are filled with absorbing material (ferrite + carbon fiber composite, absorbing from DC to 6 GHz) to absorb unwanted reflected signals. The connector and housing utilize a stepped seal structure with a PTFE insulating gasket to prevent signal reflections caused by air gaps (air gap reflection loss ≤ -40 dB at 3 GHz). Guaranteed Mechanical Precision:

　　The SMA-J (or N-J, optional) standard connector features an inner conductor tip length of 1.6 ± 0.01 mm and an insertion depth of 3.2 ± 0.02 mm, complying with IEC 61169-16 calibration-grade connector specifications. The thread clearance is ≤ 0.03 mm, and the contact resistance is ≤ 2 mΩ at a tightening torque of 6 ± 0.5 N·m, ensuring contact stability within the DC-3 GHz frequency band. II. Core Performance (DC-3GHz Low Reflection + Calibration Function)

　　1. Wideband Low Reflection Characteristics (Calibration-Grade Specifications)

　　Measured Key Parameters:

　　In the DC-1GHz band, reflection coefficient ≤-35dB, VSWR ≤1.05, insertion loss ≤0.05dB, and impedance deviation ±0.3Ω; in the 1GHz-2GHz band, reflection coefficient ≤-32dB, VSWR ≤1.08, insertion loss ≤0.08dB, and impedance deviation ±0.4Ω; in the 2GHz-3GHz band, reflection coefficient ≤-28dB, VSWR ≤1.10, insertion loss ≤0.10dB, and impedance deviation ±0.5Ω. This performance far exceeds the typical reflection coefficient requirement of ≤-20dB for conventional terminators in the DC-2GHz band. Reflection suppression in the 3GHz band is improved by 40%, effectively eliminating reflection errors in the calibration system. Low Reflection Principle:

　　This design utilizes a triple-factor "impedance gradient + absorbing load + sealed structure": ① The microstrip line's impedance gradient eliminates impedance abruptness within the frequency band; ② The composite absorbing material absorbs residual reflected signals at the load end (absorption efficiency ≥ 99%); and ③ The air-gap-free sealed structure eliminates interface reflections, ensuring consistent reflection coefficient compliance across the entire DC-3 GHz frequency band.

　　2. Calibration Function Compatibility (Compatible with RF Test Calibration Procedures)

　　Calibration Standard Compatibility:

　　This device complies with the ANSI/CTIA-2021.11 RF Test Calibration Specification and the IEC 62037-3 calibration load standard. It can be used as a "load standard" in vector network analyzer (VNA) calibration kits to correct for reflection errors in the test system (including system errors such as port mismatch and cable loss). Supports two mainstream calibration methods: "SOLT" (Short-Open-Load-Thru) and "TRL" (Thru-Reflect-Transmission Line), and is compatible with mainstream VNAs such as the Keysight N9928A and Rohde & Schwarz ZNB.

　　Guaranteed Calibration Accuracy:

　　A built-in temperature sensor (accuracy ±0.1°C) provides real-time compensation for the effect of ambient temperature on impedance (impedance correction ≤ 0.02Ω for every 1°C temperature change). Includes a NIST-traceable calibration certificate, noting the measured S11 parameters at 10 key frequency points within the DC-3GHz band (0.1GHz, 0.5GHz, 1GHz, 1.5GHz, 2GHz, 2.2GHz, 2.5GHz, 2.7GHz, 2.9GHz, and 3GHz). The calibration is valid for 12 months. III. Calibration and Test Scenario Applications (DC-3GHz Frequency Band)

　　1. RF Test System Calibration (Core Scenario)

　　VNA System Error Correction:

　　In satellite communications and 5G base station RF module testing, this terminator is connected to the VNA test port as a "load standard." Calibration software collects S11 data in the DC-3GHz frequency band to correct the test system's "reflection tracking error" (including test cable reflection loss and connector mismatch error). After calibration, the VNA's reflection coefficient error measured through a 75Ω load is reduced from ±0.5dB to ±0.1dB, ensuring test accuracy for devices such as satellite LNBs and 5G radio frequency units.

　　Multi-port Device Calibration:

　　Suitable for calibrating multi-port devices such as 8-port RF switch matrices and satellite signal distributors. Connect this terminator to an unused port (its low reflection characteristic prevents port reflection interference) and use the calibration software to perform "port isolation calibration." The measured isolation error within the 3GHz frequency band is ≤0.3dB, far superior to the ±1dB error in the uncalibrated state. 2. Wideband Device Performance Verification (Extended Scenario)

　　Satellite Communication Equipment Testing:

　　In DC-3GHz satellite Ku/C-band dual-mode device testing, this terminator simulates a satellite antenna load to verify the device's output impedance matching across the entire frequency band (the device output reflection coefficient is ≤-25dB at 3GHz, complying with satellite communication standards). Its low reflection characteristics prevent load reflections from causing self-oscillation in the device's power amplifier (PA).

　　Radar and Navigation System Calibration:

　　In testing marine navigation radar (operating in the 2-3GHz frequency band), it serves as a calibration load to verify the radar transmitter's power flatness (power fluctuation ≤0.2dB in the DC-3GHz band). The calibration function also compensates for test cable insertion loss, ensuring power measurement accuracy of ±0.1dB. IV. Calibration Maintenance and Reliability Assurance

　　1. Calibration Cycle and Operational Procedures

　　Regular Calibration Specifications:

　　Recommended calibration cycle: 12 months for laboratory environments and 6 months for outdoor testing. Calibration must be performed by a CNAS-accredited laboratory using a standard VNA (such as the Keysight N5247A) and a calibration kit. A three-step process of "impedance measurement → reflection coefficient scan → temperature compensation verification" is performed to ensure that parameters meet standards across the DC-3 GHz frequency band.

　　On-site Calibration Adaptation:

　　Supports "on-site comparison calibration" using a portable calibrator (such as the Rohde & Schwarz ZVL) to quickly verify the reflection coefficient at key frequency points (1 GHz, 2 GHz, and 3 GHz) at the test site. Deviations exceeding ±1 dB require return to the factory for recalibration. 2. Reliability and Lifespan

　　Environmental Adaptability:

　　Operating temperature range: -55°C-85°C (military-grade standard). Impedance deviation ≤ ±0.6Ω at -55°C, reflection coefficient ≤ -26dB (3GHz) at 85°C. IP65 protection rating, dust and water-resistant design suitable for outdoor testing. Salt spray test for 96 hours without oxidation corrosion.

　　Durability:

　　Connector plug-in/plug-out life ≥ 1000 cycles (500 cycles for standard terminators). Contact resistance ≤ 3mΩ after 1000 plug-in/plug cycles. Vacuum sealant (epoxy resin potting compound, dielectric strength ≥ 20kV/mm) is used between the internal resistor and the PCB solder joints to prevent desoldering caused by vibration (compliant with MIL-STD-883H vibration test standards). Certifications and Compliance:

　　Compliant with RoHS 2.0 and REACH environmental standards, and certified for CE (EN 61000-6-3) and FCC Part 15B electromagnetic compatibility. Calibration data is traceable to international standards (SI units), meeting regulatory compliance requirements for RF testing.

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