Automotive Antenna Research Articles

Sub‐6 GHz plane wave generator design for automotive antenna over‐the‐air testing

AbstractAutomotive antennas are gaining importance due to their increasingly important role for autonomous driving with the development of the Internet of Vehicles. However, over‐the‐air testing on automotive antennas is difficult owing to its large volume and complex body structure. Plane wave generators can approximate uniform plane waves in the near field of the device under test, which can greatly reduce the measurement distance and thereby decreasing the cost compared with direct far‐field solutions. This letter designs three plane wave generators for three quiet zone sizes selected according to the vehicle structure at 5.9 GHz, achieving quiet zone sizes of 1.45 m m, 2.9m m, and 3.9 m m, respectively. Within the three quiet zones, amplitude deviations of 0.82, 0.34, and 0.34 dB and phase deviations of , and are realized, respectively, according to the numerical simulations. Uncertainty analysis is further implemented to investigate the robustness of the designed PWGs proposed in this letter.

Design and measurement of a thirty-two-port MIMO/diversity antenna based on radiator-ground isomorphic inverse approach for intelligent vehicular internet of things communications

The increased demand for automobile applications and connected-vehicles in the market has prompted much research into intelligent automotive antennas. Connected-vehicles are being used to change automotive technology and serve as a framework for a smart society. This paper presents a thirty-two-port hex‑polarized massive multiple-input-multiple-output (MIMO) antenna that operates at GPS, Wi-Fi, and ultra-wideband (UWB) frequencies. In the proposed MIMO antenna, thirty-two-unit cells are populated in 3D configuration, where eight-unit cells are arranged in the horizontal plane and twenty-four-unit cells are arranged in four different vertical planes. The unit cell, based on an isomorphic inverse approach, consists of a semi-circular radiator with integrated meandered slots and achieves a tri-band operation at 1.5 GHz, 2.4 GHz, and 3.1 to 11 GHz. The unit cell has a size of 20 mm × 20 mm and the developed MIMO architecture has dimensions of 85 mm × 85 mm. The peak gain of the proposed antenna is 3.85 dBi, and the efficiency is 89.5%. The MIMO antenna assembly exhibits a calculated Envelope Correlation Coefficient (ECC) using far-field, less than 0.1. The Total Active Reflection Coefficient (TARC) is found to be less than -10 dB and the difference of Mean Effective gain (MEG) is less than 1 dB. Also, Apparent Diversity Gain (ADG) and Effective Diversity Gain (EDG) by far-field method are found to be above 9 dB. Antenna assemblies like the one proposed, are filled in various layouts on 3D vehicular space to combat the diversity reception issues, catering to spatial and polarization needs. In order to substantially validate the designed MIMO antenna for vehicular applications, housing effects and on-car analysis have been studied.

Quad-port multiservice integrated optically transparent automotive antenna for vehicular classification applications

The demand for vehicular antennas increases in tandem with the need for multiple features in automobiles. The development of optically transparent antenna (OTA) has made it possible to deploy antennas on delicate surfaces such as glass. Earlier studies on OTA demonstrated its viability using materials such as transparent conducting oxides (TCO) and conductive polymers. A tri-band OTA is proposed in this paper for vehicular applications. The antenna operates at 1.8 GHz, 2.4 GHz and 3.39–12 GHz bands, covering automotive/wireless applications such as GSM, Bluetooth, Wi-Fi, vehicular communication and electronic toll collection. The proposed OTA is developed on soda lime glass, and the material TCO is used for the radiator and the ground plane. The antenna prototype is tested on windshield and in an anechoic chamber, the gain and efficiency are found to be greater than 1 dBi and 80%, respectively. Furthermore, a machine learning technique for vehicle classification is proposed, which could help in electronic toll collection, automatic vehicle identifier, and parking management applications. The presented algorithm achieves 80% classification accuracy with a minimum window size.

A Comprehensive Review on Automotive Antennas for Short Range Radar Communications

A Comprehensive Review on Automotive Antennas for Short Range Radar Communications

A Compact and Wideband Dashboard Antenna for Vehicular LTE/5G Wireless Communications

A wideband, low-profile, 3D automotive antenna for Long-Term Evolution (LTE) and 5G applications is presented in this paper. Different from other cellular antennas typically placed under the shark-fin cover or inside a car’s plastic spoiler, the proposed antenna is designed to be integrated inside the vehicle’s dashboard. The 35.5 × 40 × 45 mm3 antenna is compact, lightweight and robust. At the same time, this antenna is capable of operating from 670 up to 5000 MHz, covering the entire LTE/5G band (overall fractional bandwidth of 198%). A shunt stub was introduced between the monopole and ground plane to achieve a low LTE band and provide mechanical robustness for the proposed structure. Simulated performance in terms of reflection coefficient, radiation pattern and realized gain is described, showing a good agreement with the measurement results. Specifically, the antenna has a gain higher than −1 dBi at the low-frequency band (i.e., below 1 GHz) and higher than 3 dBi at the upper-frequency band (i.e., above 1.7 GHz). As per requirements, the ground plane size and layout can be properly chosen to fit the antenna into the available volume as well as to optimize the antenna’s performance.

High gain modified Vivaldi vehicular antenna for IoV communications in 5G network

While targeting the sixth generation (6G) wireless communication which incorporates mainly the Internet of Things (IoT), the Internet of Vehicles (IoV) becomes a vital component to be implemented. A vehicular antenna is designed by using the modified design of the Vivaldi antenna that can cover all the frequency bands for the long-term evolution (LTE) and the mid-band fifth-generation (5G) wireless systems (ranging from 3.3 GHz to 6.5 GHz). The proposed design is optimized by analyzing the effect of the variation in the dimensions of the antenna, changing the position of the taper, the rectangular slot dimensions and the diameter of the circular slot etc. The presented automotive antenna operates at four frequency bands ranging from 3.62 GHz - 4.03 GHz (410 MHz), 4.17 GHz–5.38 GHz (1210 MHz), 5.57 GHz–6.16 GHz (590 MHz) and from 6.23 GHz - 6.64 GHz (410 MHz) with the minimum reflection coefficient of -39 dB, -39.06 dB, -50.42 dB and -12.45 dB, respectively. The proposed antenna offers the high gain of 7.6 dB, 6.7 dB, 9.3 dB and 7.4 dB for the four bands of the operating spectrum, respectively. The analysis of the reflection and radiation characteristics of the antenna when placed on the vehicle confirms the suitability of an antenna for the smart vehicle to vehicle communications.

Comparing and Analysis of Test and Evaluation Methods for Connected Vehicle Communication Antenna System

With the development of Connected Vehicle, various of on-board applications and functions rely on stable, reliable and fast-response wireless connections furtherly, making it more urgent and widespread for vehicles to be equipped with relevant antenna systems such as positioning and communication. There are many types of vehicle antenna systems, together with a wide range of installation locations and a complex electronic environment which brings a huge challenges to the development of antenna manufacturers and the matching of automobile OEMs. In order to carry out the R&D, matching and testing of the vehicle antenna system better, various parties have proposed a multi-dimensional test and evaluation methods, but there is still a lack of horizontal evaluation between them. This paper analyses the requirements of automotive antenna system evaluation, sorts out and compares the technical paths of various common solutions, summarizes the characteristics and differences of various solutions, and provides a research foundation for further optimizing the vehicle-level antenna system test and evaluation program.

Dual Band GNSS Antenna Phase Center Characterization for Automotive Applications

High-accuracy Global Navigation Satellite System (GNSS) positioning is a prospective technology that will be used in future automotive navigation systems. This system will be a composite of the United States' Global Positioning System (GPS), the Russian Federation's Global Orbiting Navigation Satellite System (GLONASS), China Beidou Navigation Satellite System (BDS) and the European Union’s Galileo. The major improvement in accuracy and precision is based on (1) multiband signal transmitting, (2) carrier phase correction, (3) Real Time Kinematic (RTK). Due to the size and high-cost of today’s survey-grade antenna solutions, this kind of technology is difficult to use widely in the automotive sector. In this paper, a low-cost small size dual-band ceramic GNSS patch antenna is presented from design to real sample. A further study of this patch antenna illustrates the absolute phase center variation measured in an indoor range to achieve a received signal phase error correction. In addition, this low-cost antenna solution is investigated when integrated into a standard multi-band automotive antenna product. This product is evaluated both on its own in an indoor range and on a typical vehicle roof at an outdoor range. By using this evaluation file to estimate the receiver position could achieve phase motion error-free result.

Experimental comparison of absorber and conductive floor automotive near field antenna measurement systems

AbstractLarge truncated spherical near-field systems with conductive or absorbing floors are typically used in the measurement of the performances of vehicle-installed antennas. The main advantage of conductive floor systems is the ease of accommodation of the vehicle under test, but their performances are affected by the interaction with the reflecting ground floor. Instead, absorbing-based systems emulating free-space conditions minimize the effect of the interaction with the floor, but generally require longer setup times, especially at lower frequencies (70–400 MHz), where bulky absorbers are typically used to improve reflectivity levels. Considering scaled measurements of a vehicle model, the performances of these two typical implementations are analyzed in the 84–1500 MHz range and compared to free-space measurements. Absorbers with different dimensions and reflectivity have been installed in the scaled measurement setup, and measured data have been investigated with proper post-processing to verify the applicability to realistic systems. Figures of merit of interest for automotive applications, like gain and partial radiated powers, have been compared to free-space to evaluate the impact of different scenarios.

Research on Evaluation Index of Automotive Antenna Testing

Mounted locations and the ground plane structure have remarkable influences on the performance of roof-mounted automotive antennas. To distinguish this influence in radiation, figure of merits (FoMs), including total radiated power (TRP), near-horizontal part radiated power (NHPRP), and cumulative distribution function (CDF), are studied in this paper. It is proved that TRPs are almost the same with different mounting configurations. Because the radiation toward the horizon is a critical performance metric for automotive antennas, NHPRP is analyzed within certain degrees near the horizon. Even though a bigger deviation has been observed in NHPRP, the discrimination between different mounted scenarios is still not enough. Different from TPR and NHPRP, which are efficiency-based FoMs, CDF combines the gain values and the pattern shape together, achieving a comprehensive and intuitive insight into the antenna performance. It is more predictive and distinguishable in terms of the radiation pattern than NHPRP and TRP. Therefore, CDF can be utilized as a good supplement to existing metrics and can better distinguish the radiation performance of different antenna mounting configurations.

Cross Polarized 2x2 LTE MIMO System for Automotive Shark Fin Application

In this research we propose two orthogonally placed FR4 printed planar monopole antenna elements for use in the automobile roof top shark fin antenna for LTE MIMO applications. The discussed MIMO antenna system is designed to cover the worldwide LTE frequency band from 698MHz to 2700MHz. The goal of this research is to achieve satisfactory MIMO performance across the whole band while staying within physical constraints of the shark fin style antenna. The target reflection coefficient (S11) of each element is -6dB. Because of physical constraints of the automotive shark fin design antenna MIMO decorrelation is achieved by cross polarization and small distance separation. Correlation better than -12dB is targeted and achieved in higher bands, while in lower frequency bands antennas would not benefit from MIMO performance. Numerical simulation of the MIMO antenna system is performed using FEKO in order to verify the design parameters. Simulation findings are confirmed by manufacturing antennas and testing in the lab.

24 GHz Horizontally Polarized Automotive Antenna Arrays With Wide Fan Beam and High Gain

In this paper, two 24 GHz horizontally polarized 1 × 8 patch antenna arrays were developed for automotive radar applications. The proposed antenna arrays offer the advantages of wide fan beams and high gain. The far-field radiation patterns are widened in the E-plane by disturbing the near-field distribution of each driven patch. In Design I, the driven patch is loaded with a parasitic loop, which functions as a director in the E-plane. Due to the directing effect, the E-plane beamwidth can be increased. The experimental verification prepared for Design I showed that a beamwidth of 130° and a gain of 12.2 dBi can be achieved through this method. To further enhance the beamwidth, another array with each patch loaded with parasitic mushroom-like elements was proposed by Design II. The PMLEs are 180° out of phase to their corresponding driven patch. The cancelation effects can be properly managed to slightly sacrifice the gain of the array in return for a wider beamwidth in the E-plane. Design II exhibits a wider beamwidth of 150° and a lower gain of 11.1 dBi.

Automotive Antenna Roof for Cooperative Connected Driving

An automotive concept for vehicular communications is proposed that utilizes the potential of the roof area for antennas. Antennas are distributed in cavities and on shelves in the center and on the front and rear roof ends. The arrangement of antennas on the roof allows better radiation to the front and back of automobiles than shark-fins and single cavities. Combining several modules provides space for further antennas, sensors, and integrated front-ends, as well as better spatial separation for multiple-input multiple-output (MIMO) arrays beyond 5G, and cooperative connected and automated driving. A prototype was developed and built into a car chassis. The measured data were analyzed and evaluated in the view of coverage for vulnerable road users and on correlation for the MIMO.

Over-The-Air Testing of Automotive Antennas and Wireless Links in The Installed State on The Basis of LTE Downlink Communication Parameters

Over-The-Air Testing of Automotive Antennas and Wireless Links in The Installed State on The Basis of LTE Downlink Communication Parameters

An immersed boundary method to conjugate heat transfer problems in complex geometries. Application to an automotive antenna

Considering that the most common reason for electronic component failure is the excessive temperature level, an efficient thermal management design can prolong the operating life of the equipment, while also increasing its performance. Computational Fluid Dynamics and Heat Transfer (CFD&HT) have proved valuable in the study of these problems, since they can produce reliable fields of fluid flow, temperature and heat fluxes. Moreover, thanks to the recent advances in high-performance computers, CFD&HT numerical simulations are becoming viable tools to study real problems. The conventional approach, which consists of employing body-conformal meshes to the solids and fluids regions, often results costly and ineffective in applications with very complex geometries and large deformation. For these cases, an alternative approach, the Immersed Boundary Method (IBM), which employs a non-body conformal mesh and discretizes the entire domain using a special treatment in the vicinity of the solid-fluid interfaces, has proven more effective. In this work, an IBM was extended to simulate problems with conjugate heat transfer (CHT) boundary conditions taking into account the radiative exchange between surfaces. It was designed to work with any type of mesh (domain discretization) and to handle any body geometry. The implementation was validated and verified by several simulations of benchmark cases. Moreover, the IBM was applied in an industrial application which consists of the simulation of a Smart Antenna Module (SAM). All in all, the carried out studies resulted in a monolithic methodology for the simulation of realistic situations, where all three heat transfer mechanisms can be considered in complex geometries.

자동차 전면 글래스용 FM 대역 투명 모노폴 안테나

A transparent antenna designed on the front glass of an automobile operating in the FM broadcast band(88～108 MHz) is proposed. A transparent antenna designed on the front glass of the automobile to avoid space limitation is typically positioned as a roof-mounted shark-fin antenna. An antenna designed on the front glass can reasonably solve the problems of low reception sensitivity and radiated interference from antennas for other service bands. The front glass has a unique closed-line structure, and this structure causes the surface current to flow to the front glass’s surroundings; thus, the first resonance is caused before the broadcast band. Through the use of this closed-line structure, the surface current distribution is controlled, and an antenna for which the first resonance is operating in the frequency-modulated(FM) band can be designed. Moreover, the use of a micro-metal-mesh film that is a transparent electrode, suitable for designing a radio frequency device, enables the antenna to minimize visual perception through its transparency. The measured reflection coefficient(S11) of the antenna is less than −6 dB, and the average peak gain is −0.9 dB in the FM band. Experiments show that the transparent antenna on the front glass offers both the space and design freedom required to develop future automotive antennas.

Automotive antenna diversity system for satellite radio with high phase accuracy in low SNR-scenarios

AbstractFor a fast scan-phase satellite radio antenna diversity system a noise correction method is presented for a significant improvement of audio availability at low signal-to-noise ratio (SNR) conditions. An error analysis of the level and phase detection within the diversity system in the presence of noise leads to a correction method based on a priori knowledge of the system's noise floor. This method is described and applied in a hardware example of a satellite digital audio radio services antenna diversity circuit for fast fading conditions. Test drives, which have been performed in real fading scenarios, are described and results are analyzed statistically. Simulations of the scan-phase antenna diversity system show higher signal amplitudes and availabilities. Measurement results of dislocated antennas as well as of a diversity antenna set on a single mounting position are presented. A comparison of a diversity system with noise correction, the same system without noise correction, and a single antenna system with each other is performed. Using this new method in fast multipath fading driving scenarios underneath dense foliage with a low SNR of the antenna signals, a reduction in audio mute time by one order of magnitude compared with single antenna systems is achieved with the diversity system.

Spherical Field Transformation Above Perfectly Electrically Conducting Ground Planes

A new spherical field transformation approach for near-field measurements above perfectly electrically conducting (PEC) ground planes at arbitrary heights is presented. It provides higher order probe correction and treatment of irregular sample point locations on the measurement surface but has the same low computational complexity as the known fast Fourier transform (FFT) accelerated spherical field transformation with first-order probe correction. The infinite PEC boundary is considered by applying the image principle to the spherical modes of the device under test (DUT). Only the measurements above the ground are required to iteratively solve the inverse problem for the unknown spherical mode coefficients. Due to additional modal translation operators, the scan center of the spherical measurement system does not need to lie in the ground plane. Moreover, if the DUT is positioned at an appropriate height above the ground plane, the free-space sources of the DUT are extractable with good accuracy. By employing the nonequispaced FFT, the near field can be irregularly sampled on the spherical measurement surface. Numerical investigations show the capabilities of the proposed field transformation approach. Its practical relevance and efficiency are demonstrated for simulated automotive antenna measurements and real near-field measurements above a metallic ground.

Beam Expansion of Blind Spot Detection Radar Antennas Using a Radome with Defected Corrugated Inner Wall

A beam expanding radome for 76.5 GHz automotive radar antennas is presented whose inner surface is engraved with corrugations. The radar used for blind spot detection (BSD) requires a very wide beam width to ensure longer time for tracking out-of-sight objects. It is found that the corrugations modulate the phase velocities of the waves along the surface, which increases beam width in the far field. In addition, defects in the corrugation increase beam width even further. The presented structure satisfies the beam width requirement while keeping a low profile.

Concealed CFRP Vehicle Chassis Antenna Cavity

A concealed vehicular carbon fiber reinforced polymer cavity in the roof that contains antennas is proposed, prototyped, and measured. Compared to state-of-the-art roof-mounted shark-fin modules, this offers significantly more room for antennas and radio frequency hardware, thus enabling a smooth transition of vehicular connectivity towards 5G. Three antennas were prototyped and embedded in the cavity: two laser direct structured antennas (inverted-F antenna for 2 GHz, monopole for 5.9 GHz), as well as a broadband conical monopole antenna milled from brass that characterizes the feasible frequency range from 2 to 6 GHz by measurement. It is shown that near-omnidirectional radiation from the concealed automotive antenna cavity is achievable.