GNSS active ceramic antenna

　　The following is a detailed analysis of the GNSS Active Ceramic Antenna, covering its principles, design points and typical applications:

　　1. Core Definition and Features

　　GNSS Active Ceramic Antenna:

　　GNSS antenna that combines a ceramic dielectric substrate and an active circuit (such as a low noise amplifier, LNA), designed to improve weak signal reception performance.

　　Key Features:

　　High sensitivity: The built-in LNA can reduce the noise figure (typical value ≤ 0.5dB), suitable for indoor/complex environments.

　　Miniaturization: The high dielectric constant of ceramic dielectrics (such as LTCC, microwave ceramics) allows the antenna size to be smaller (such as 10×10×5mm³).

　　Wideband support: Covers multiple GNSS frequency bands (L1/L5/Galileo E1/E5).

　　Low Standing Wave Ratio (VSWR): Optimizes matching circuits and reduces signal reflections.

　　2. Working Principle

　　Antenna Structure:

　　Ceramic substrate: Integrated patch antenna (such as microstrip patch antenna or dipole antenna).

　　Active circuit:

　　Low noise amplifier (LNA): Improves received signal strength.

　　Filter: Suppresses out-of-band interference (such as Wi-Fi/Bluetooth signals).

　　Matching network: Optimizes impedance matching (50Ω) between antenna and RF front end (RFIC).

　　Signal flow:

　　GNSS signal → antenna reception → LNA amplification → filter denoising → RF front end demodulation → positioning algorithm processing.

　　3. Design points

　　3.1 Material selection

　　Ceramic substrate:

　　LTCC (low temperature co-fired ceramic): suitable for multi-layer integration, excellent high-frequency performance (≥5GHz).

　　Microwave ceramics (such as AlN, SiC): high thermal conductivity, suitable for high-power scenarios.

　　Metal conductor:

　　Gold/silver paste: low loss, suitable for high-frequency circuits.

　　3.2 Antenna structure optimization

　　Patch antenna design:

　　Rectangular/circular patch: balance radiation efficiency and size.

　　Multi-feed point design: support multiple frequency bands (such as L1 + L5 dual-band).

　　Grounding design:

　　Microstrip grounding: Reduce size, but avoid parasitic capacitance.

　　Via grounding: Improve high-frequency stability (such as > 2GHz).

　　3.3 Active circuit integration

　　LNA circuit:

　　NEC NE3210S01: Typical ultra-low noise LNA (NF ≤ 0.4dB).

　　Power supply design: Use 3.3V/1.8V dual power supply to reduce power consumption.

　　Filter design:

　　SAW filter: low cost, low insertion loss (<1dB).

　　BAW filter: better high-frequency performance (> 2.5GHz).

　　3.4 Isolation and shielding

　　Metal shielding cover: Prevent external electromagnetic interference (EMI).

　　Layout optimization: Keep enough distance between antenna and RF circuit (> λ/10).

　　4. Typical application scenarios

　　Consumer electronics: smart phones, smart watches, car navigation.

　　IoT devices: drone positioning, shared bicycle electronic fence.

　　Industrial field: measurement equipment, precision agricultural machinery.

　　Wearable devices: AR glasses, health monitoring bracelets.

　　5. Testing and verification

　　Key indicator tests:

　　Gain: ≥3dBi (including LNA gain).

　　Noise figure: ≤0.6dB.

　　Sensitivity: -150dBm@1.575GHz (typical value).

　　Positioning accuracy: horizontal error <1 meter (open environment).

　　Simulation tools:

　　HFSS or ADS: optimize antenna radiation pattern and circuit matching.

　　SPICE: verify LNA circuit performance (S parameters, noise figure).