Technical differences and performance comparison between GPS ceramic antennas and PCB antennas

　　Technical differences and performance comparison between GPS ceramic antennas and PCB antennas

　　In the field of satellite navigation, the antenna is the "first pass" for signal reception. Its performance directly determines the positioning accuracy (1-10 meters), cold start time (20-45 seconds) and weak signal capture capability (-160dBm to -165dBm). GPS ceramic antennas and PCB antennas are based on completely different radiation mechanisms, and show significant differences in gain characteristics, size constraints and application scenarios. Accurate matching needs to be carried out around equipment space limitations, accuracy requirements and environmental adaptability.

　　Differences in technical principles and structural design

　　Core architecture of GPS ceramic antennas

　　GPS ceramic antennas use high dielectric constant ceramic sheets (ZTA ceramics, ZrO₂-TiO₂-Al₂O₃ composite system) as the radiation core, and the dielectric constant (εr) is usually 9-11 (high-end models can reach 15), which is much higher than PCB materials (εr=4.2-4.5). Its working principle is to amplify the 1575.42MHz (L1 frequency band) signal through the electromagnetic resonance of the ceramic sheet, and form unidirectional radiation with the bottom metal reflection layer (usually copper foil, thickness ≥35μm). The gain is positively correlated with the diameter of the ceramic sheet: 25mm diameter can achieve 2.5dBi gain, and 15mm diameter drops to 1.8dBi.

　　The ceramic sheet and the PCB substrate are electrically connected through silver paste sintering (temperature 850℃), and the impedance matching network (composed of microstrip lines and capacitors) is integrated into the substrate to ensure 50Ω system matching and standing wave ratio ≤1.5@1.55-1.60GHz frequency band. High-end models will cover the ceramic surface with a ferrite layer (thickness 0.5mm), which improves the anti-interference ability by absorbing stray magnetic fields (10-1000MHz) and makes the out-of-band suppression ≥40dB.

　　Structural characteristics of PCB antennas

　　The PCB antenna is a planar antenna formed by etching metal traces (copper thickness 35-70μm) on the PCB substrate. The radiating unit is a λ/4 microstrip line (length 38mm@1575MHz), which relies on the dielectric properties of the PCB substrate (FR4 material) to achieve signal radiation. Its core design lies in the optimization of the trace shape (common inverted F type, ring), and the impedance is controlled by adjusting the line width (1-3mm) and the gap (≥2mm). The typical standing wave ratio is 1.8@1.575GHz (slightly higher than the ceramic antenna).

　　To reduce environmental interference, the PCB antenna needs to reserve a clear area (area ≥2 times the antenna size), and metal components or grounding copper foil are prohibited in the area. The edge needs to be designed with a grounding shielding frame (width ≥5mm) to reduce the motherboard noise coupling to below -85dBc. Some designs will use dual feed point technology to achieve circular polarization and improve the polarization matching of satellite signals (circular polarization axis ratio ≤3dB).

　　Comparison of key performance parameters

　　Gain and radiation efficiency

　　GPS ceramic antenna: Gain 2.0-3.0dBi, radiation efficiency 75%-85% (25mm diameter), 15%-20% higher than PCB antenna. In the zenith direction (0° incidence angle), its signal capture sensitivity can reach -165dBm, which is easier to capture weak signals (such as urban canyons, indoor window scenes) than PCB antenna (-160dBm).

　　PCB antenna: Gain 1.0-2.0dBi, radiation efficiency 60%-70% (affected by PCB dielectric loss), but the lack of gain can be compensated by multi-element design (such as 2×2), and the sensitivity is close to that of ceramic antenna in open environment.

　　Beam coverage and polarization characteristics

　　Ceramic antenna: horizontal half-power beam width ≥100°, vertical beam coverage -10° to 90° (zenith direction), right-hand circular polarization (RHCP), polarization purity ≥90%, polarization matching degree of satellite signal reaches 85% (PCB antenna is 70%).

　　PCB antenna: The beam width is wider (horizontal ≥120°), but gain depression is prone to occur in the vertical direction (±30° external attenuation ≥5dB), linear polarization or low-purity circular polarization is mostly used, and the performance is significantly reduced when the satellite signal incident angle is large (such as low latitudes).

　　Environmental adaptability

　　Temperature stability: The resonant frequency offset of the ceramic antenna is ≤±5MHz (PCB antenna is ±10MHz) in the range of -40℃ to 85℃, because the temperature coefficient of the ceramic dielectric constant (τ ε) can be controlled at ±30ppm/℃ (PCB is ±150ppm/℃).

　　Anti-interference capability: The ceramic antenna suppresses interference signals below 1.5GHz by ≥30dB (20dB for PCB antenna) through a metal shield (coverage ≥90%), and the positioning accuracy fluctuation in industrial electromagnetic environments (such as near motors and inverters) is ≤1 meter (2-3 meters for PCB antenna).

　　Design constraints and application scenarios

　　Size and space limitations

　　Ceramic antenna: size is positively correlated with performance. The 25mm diameter model has a gain of 3dBi but needs to occupy a space of ≥30mm×30mm. The gain of the 10mm miniature model is reduced to 1.5dBi, which is suitable for medium-space equipment (such as vehicle navigation and drones).

　　PCB antenna: It can be integrated with the motherboard (area ≤20mm×20mm) without additional packaging, which is suitable for space-constrained scenarios (such as smart watches and Bluetooth headsets), but a clearance area of ≥5mm must be reserved (there is no such requirement for ceramic antennas).

　　Typical application adaptation

　　GPS ceramic antenna:

　　In-vehicle navigation terminal: 25mm diameter model with LNA (noise coefficient 1.0dB), cold start time ≤25 seconds, positioning accuracy 2-3 meters, support for weak signal capture in tunnels (-163dBm).

　　Mapping drone: 30mm high gain model (3.5dBi), multipath suppression ratio ≥20dB, positioning accuracy of 1 meter in urban buildings.

　　Maritime navigation equipment: waterproof ceramic antenna (IP67), performance attenuation ≤0.5dB after 1000 hours of salt spray test, adapt to high humidity environment in the ocean.

　　PCB antenna:

　　Smartphone: integrated on the top of the motherboard (15mm×15mm), with MIMO diversity design, positioning accuracy of 5-8 meters in open areas, meeting daily navigation needs.

　　Smart wearable devices: 10mm×10mm micro PCB antenna, power consumption ≤1μA (ceramic antenna is 5μA), support intermittent positioning (1 time/minute), and extend battery life by 30%.

　　IoT tracker: Linear polarization PCB antenna, cost is 50% lower than ceramic antenna, positioning error is ≤10 meters in open areas (such as logistics warehouses), meeting the basic needs of asset tracking.

　　Technical framework for selection decision

　　Accuracy requirements: When the positioning accuracy requirement is ≤3 meters, ceramic antennas (such as professional navigation) are preferred, and PCB antennas (such as consumer electronics) can be selected for 5-10 meters.

　　Space restrictions: PCB antennas must be used when the internal space of the device is <20mm×20mm, and ceramic antennas are preferred when external or medium space (≥30mm) is allowed.

　　Environmental conditions: Ceramic antennas (anti-interference + temperature stability) are required in complex environments such as industrial and vehicle-mounted environments, and PCB antennas can be selected for indoor consumer scenarios.

　　Cost-sensitive: Large-scale consumer devices (such as smartphones) choose PCB antennas (cost per set < $1), while professional devices (such as surveyors) accept the cost of ceramic antennas (3-5 dollars).

　　The essential difference between GPS ceramic antennas and PCB antennas lies in the balance of "performance-size-cost": ceramic antennas trade space for performance and are suitable for mid-to-high-end positioning scenarios; PCB antennas trade performance for integration and dominate the consumer electronics market. In actual applications, the two are not substitutes, but complement each other through scene segmentation, jointly supporting satellite positioning needs in all fields from daily navigation to professional surveying and mapping.