A defining feature of GNSS RTK car antennas is their form factor and mounting flexibility, tailored to integrate seamlessly with various vehicle types—from compact cars to commercial trucks. These antennas are typically low-profile, with heights ranging from 10mm to 30mm, allowing them to be mounted on the roof, trunk, or dashboard without obstructing the driver’s view or creating aerodynamic drag. Roof mounting is preferred for optimal sky visibility, as it minimizes signal blockage from the vehicle’s metal body, which can attenuate GNSS signals by 20 dB or more. To ensure secure attachment, antennas use robust mounting mechanisms such as adhesive pads, magnetic bases, or screw mounts. Adhesive pads offer quick installation and are ideal for rental or leased vehicles where permanent modification is undesirable, while magnetic bases provide strong holding force (often up to 5 kg) for temporary mounting on metal surfaces. Screw mounts, though more permanent, offer the highest stability, critical for high-speed vehicles where vibration could displace the antenna and disrupt signal reception. The compact design also allows for integration into OEM (Original Equipment Manufacturer) systems, where antennas are embedded into the vehicle’s roof rail or windshield, combining functionality with aesthetics.

The material composition of GNSS RTK car antennas is carefully selected to balance durability, signal transparency, and EMI resistance. The outer housing is typically made from UV-resistant ABS or polycarbonate, materials that withstand prolonged exposure to sunlight, rain, and temperature extremes—from -40°C in cold climates to +85°C in desert conditions. These materials are also non-conductive, ensuring they do not interfere with RF signals. Beneath the housing, the antenna’s radiating element is often a ceramic patch, chosen for its high dielectric constant (εr = 20–40) which enables miniaturization while maintaining resonance at GNSS frequencies. The ceramic patch is mounted on a PCB that integrates a low-noise amplifier (LNA), bandpass filters, and a ground plane. The ground plane, usually a copper layer, serves dual purposes: it enhances the antenna’s radiation pattern by reflecting signals upward and shields the sensitive electronics from EMI generated by the vehicle’s engine, alternator, and infotainment systems. Some advanced designs include a ferrite layer between the PCB and housing to further suppress EMI, reducing noise floor by up to 10 dB in high-interference environments.

Polarization is a critical design consideration for GNSS RTK car antennas, with RHCP (Right-Hand Circular Polarization) being the standard choice. Vehicle motion—including pitching, rolling, and yawing—causes constant changes in the antenna’s orientation relative to satellites. RHCP ensures that the antenna can receive signals regardless of this motion, as circularly polarized signals rotate in a helical pattern that matches the antenna’s polarization. This is in contrast to linear polarization, which would suffer significant signal loss (up to 20 dB) when the antenna tilts even slightly. RHCP also mitigates multipath interference, a major source of error in automotive environments. Multipath occurs when GNSS signals reflect off buildings, road surfaces, or the vehicle’s own body, creating delayed signals that corrupt the receiver’s measurements. Since reflected signals often have reversed polarization, RHCP antennas reject most cross-polarized multipath signals, reducing positioning errors by 50% or more in urban canyons. This capability is essential for RTK systems, where multipath-induced errors could otherwise degrade accuracy from centimeters to meters.

The frequency coverage of GNSS RTK car antennas is designed to support multiple satellite constellations and bands, ensuring robust positioning even in challenging conditions. These antennas typically cover GPS L1/L2, GLONASS G1/G2, BeiDou B1/B2, and Galileo E1/E5b, leveraging the redundancy of multi-constellation reception to maintain lock when individual satellites are obstructed. Dual-band support (e.g., L1 and L2) is particularly critical for RTK, as it enables ionospheric delay correction. The ionosphere introduces frequency-dependent delays that can vary by up to 50 meters, but by measuring signals at two frequencies, the receiver can model and cancel these delays, a process that improves accuracy by a factor of 10 in ionospherically active regions. Some antennas also include 4G LTE or 5G bands (e.g., 600 MHz–6 GHz) to enable simultaneous communication, allowing the vehicle to receive RTK correction data via cellular networks. This integration eliminates the need for a separate communication antenna, reducing installation complexity and cost.

Gain and radiation pattern are optimized to balance signal strength and coverage, addressing the unique challenges of vehicular positioning. GNSS RTK car antennas typically offer a gain of 25–30 dBi, sufficient to amplify weak signals (as low as -160 dBm) received through the vehicle’s roof or windshield. The gain is concentrated in a hemispherical radiation pattern with a beamwidth of 60–90 degrees, ensuring coverage of satellites from the horizon up to the zenith. This pattern is critical for urban driving, where tall buildings restrict the visible sky to a narrow cone. The antenna’s radiation pattern is also engineered to minimize gain in the downward direction, reducing interference from ground-based sources like cellular towers or Wi-Fi routers. To further enhance performance, some antennas use beamforming technology, dynamically adjusting their radiation pattern to focus on satellites with the strongest signals—a feature that improves signal-to-noise ratio (SNR) by 3–5 dB in dense urban environments.