Global Navigation Satellite System Bands Research Articles

Multiband circularly-polarized stacked elliptical patch antenna with eye-shaped slot for GNSS applications

Abstract This paper introduces a tri-band stacked elliptical patch antenna featuring a right-handed circular polarized, designed to operate at the L2, L5, and L1 Global Navigation Satellite System bands. Initially, an elliptic patch is constructed and fed by a probe feed to generate TM110 and TM210 modes at resonance frequencies calculated using Mathieu functions. The probe position is precisely adjusted to excite the quasi-orthogonal mode of TM110 to generate circularly polarized (CP) waves at the L2 and L5 bands. Subsequently, an eye-shaped aperture is engraved into the elliptical patch to enhance the axial ratio (AR) beamwidth in the L2 and L5 bands and stimulate the orthogonal mode of TM210 to produce CP waves at the L1 band. Lastly, a stacked partially elliptical parasitic element is placed beneath the upper slotted elliptical patch to enhance the orthogonality of TM210 surface current versions and thus improve the AR beamwidth at the L1 band. The proposed antenna shows low reflection coefficient values at 1.12–1.33 (L2/L5), and 1.5–1.66 GHz (L1). The AR beamwidths are 133/213∘, 167/163∘, and 36/103∘ at two orthogonal cutplanes at L5, L2, and L1 bands, respectively. The antenna also has decent gains of 6–6.9 dBic across the three bands.

GNSS interference monitoring and detection based on the Swedish CORS network SWEPOS

Abstract The presence of Global Navigation Satellite System (GNSS) interference poses a significant risk to both GNSS and the infrastructures that depend on them. This article describes how an existing GNSS infrastructure, the Swedish Continuously Operating Reference Stations network SWEPOS with more than 500 stations, can be leveraged to control the quality of GNSS signals and to be able to detect interferences in GNSS and adjacent frequency bands. This study introduces a SWEPOS-based automatic system that effectively detects GNSS interference by examining the signal-to-noise ratio (SNR) of Global Positioning System, Globalnaya Navigatsionnaya Sputnikovaya Sistema, Galileo, and BeiDou frequency bands. By comparing the SNR of tracked satellites against historical data, the system detects radio frequency interference (RFI) by statistically characterizing the SNR of simultaneously tracked satellites. Furthermore, based on the SNR characteristics across satellites, the system distinguishes between RFI and non-RFI sources. The effectiveness of the detection system is demonstrated through both simulated signal interference waves and real-world interference events.

A Lightweight Low-Profile GNSS Antenna Based on Wideband Multipath Mitigation Strategy

A new light-weight low-profile antenna based on wideband multipath mitigation strategy for high precision global navigation satellite system (GNSS) is presented. The multipath mitigation strategy is realized by using two shorted rings and several discretely distributed absorbing materials. The two shorted metal rings can improve the spatial axial ratio and broaden the pattern beamwidth, and the absorbing materials significantly enhance the multipath mitigation performance. One prototype of the proposed light-weight GNSS antenna is designed and fabricated for demonstration. The measured results show that the front-to-back ratio (FBR) is over 30 dB across the entire GNSS bands (1.16-1.28GHz and 1.53-1.62GHz). The 3dB spatial axial ratio and 3dB beamwidth is about ±82° and 80°. The proposed antenna performs similarly to its counterpart but with a lighter weight of about 1.2kg and a lower profile size of 70mm.

Additive Manufacturing of Linear Continuous Permittivity Profiles and Their Application to Cylindrical Dielectric Resonator Antennas

The utilization of additive manufacturing (AM) to engineer the permittivity profile of dielectric resonator antennas (DRAs) is considered. For the first time, the capabilities of AM are exploited to create continuously swept permittivity profiles and applied to cylindrical DRAs. The spatial variant lattices (SVL) synthesis algorithm is implemented to create the desired permittivity profiles from a single material, and resulting geometries are manufactured using a high-permittivity material in a fused deposition modeling AM process. Three individual antennas for global navigation satellite system bands are designed and manufactured, two inhomogeneous DRAs with continuous permittivity profiles along the radial and vertical axis, and one homogeneous DRA for comparison. The manufactured antennas are characterized by impedance, realized gain, and axial ratio. Experimental results agree well with simulations and show increased impedance-, gain-, and axial-ratio bandwidths for both inhomogeneous antennas compared to the homogeneous one.

Highly Integrated Multifunctional Antenna for Global Navigation Satellite System

This communication proposes a new highly integrated multifunctional global navigation satellite system (GNSS) antenna used for navigation or surveying high-precision area, the fourth-generation (4G) mobile communication, and short-distance wireless communication. The antenna consists of four elements, saying: 1) a low-profile navigation element on one substrate covering all the GNSS bands and 2) two long-term evolution multiple-input–multiple-output (LTE-MIMO) elements and one Wi-Fi element uniformly distributed on the edge of the substrate. This symmetrical configuration ensures the navigation element’s low axial ratio (AR) and radiation pattern symmetry, as well as navigation accuracy. In addition, to enhance the isolation between the GNSS element and other three elements under high integration, these three elements are designed to avoid resonating within the GNSS bands. The measured peak gains of the GNSS element are 6.0 dBi from 1.16 to 1.28 GHz and 6.5 dBi from 1.52 to 1.62 GHz. The −6 dB impedance bandwidth of the LTE-MIMO elements can cover 840–960, 1800–2200, and 2500–2700 MHz. The distance communication of the Wi-Fi element is 80 m. The experimental results indicate that the proposed multifunctional antenna features low profile, high integration, and wideband, implying potential application in the multifunctional satellite navigation system.

Quad-Band Circular Polarized Antenna for GNSS, 5G and WIFI-6E Applications

A quad-band circularly-polarized antenna, for applications of a global navigation satellite system (GNSS), 5G, and WIFI-6E, is designed, fabricated, and measured. The proposed antenna is formed by an L-shaped radiator, a rectangular frame ground with an L-shaped stub, and a rectangular strip at the opposite corner. The microstrip antenna can generate four frequency bands, covering WIFI-6E (5925–7125 MHz), 5G n77 (3300–4200 MHz), n78 (3300–3800 MHz), and the GNSS bands. This antenna generates right hand circular polarization (RHCP) waves in the low frequency band (0.95–2.11 GHz), covering GPS, BDS, GLONASS, and GALILEO applications. Moreover, an L-shaped aperture and three rectangular slits are cut on the ground to broaden the axial-ratio bandwidth at the upper band. A prototype is fabricated and measured to verify the performance of this design. It is shown that the agreement between the simulation and measurement is satisfactorily good. The measured −10 dB bandwidths for each band are 75.8% (0.95–2.11 GHz), 55.8% (3.05–5.39 GHz), 39.9% (5.84–8.19 GHz) and 10.3% (9.14–10.68 GHz), respectively. While the measured 3 dB axial-ratio bandwidths are 59.4% (1.16–2.14 GHz), 35.8% (3.23–4.64 GHz), 8.4% (5.70–6.20 GHz), and 2.6% (7.51–7.71 GHz), the measured gains are 4.56, 2.28, 4.26, and 4.30 dBi at 1.5 GHz, 3.8 GHz, 6 GHz, and 7.6 GHz, respectively.

A Design of Wideband Circularly Polarized Antenna With Stable Phase Center Over the Whole GNSS Bands

In this letter, a simple crossed-dipole antenna with four parasitic plates is designed to realize a stable phase center. Owing to the high symmetry of crossed dipole, its phase center within a narrow solid region can remain stable. By adding parasitic plates rotationally on the reflector, beamwidth of stable phase center is widened. Both simulation and measurement of the designed antenna yield a –10 dB impedance bandwidth of 63.2% and a 3 dB axial-ratio bandwidth of 52.4%, covering all the global navigation satellite system (GNSS) bands. For each GNSS band, a phase center variation is retained below 3° above the 10° elevation. Over the whole GNSS bands, phase center deviation with frequency is retained below 1.1 mm.

Jammer Classification in GNSS Bands Via Machine Learning Algorithms.

This paper proposes to treat the jammer classification problem in the Global Navigation Satellite System bands as a black-and-white image classification problem, based on a time-frequency analysis and image mapping of a jammed signal. The paper also proposes to apply machine learning approaches in order to sort the received signal into six classes, namely five classes when the jammer is present with different jammer types and one class where the jammer is absent. The algorithms based on support vector machines show up to accuracy in classification, and the algorithms based on convolutional neural networks show up to accuracy in classification. The training and test databases generated for these tests are also provided in open access.

A Wideband Circularly Polarized Crossed-Slot Antenna With Stable Phase Center

A wideband circularly polarized crossed-slot antenna with a stable phase center is investigated in this letter. The proposed antenna consists of a crossed-slot radiator and a Γ-shaped feeding structure. Orthogonal modes can be excited by perturbing the crossed slot to realize circular polarization. Both simulation and measurement of the designed antenna demonstrate a –10 dB impedance bandwidth of 43.8% and a 3 dB axial-ratio bandwidth of 42.6%, covering all the global navigation satellite system (GNSS) bands. Due to the overall symmetry of the radiation crossed slot, a phase center of the proposed antenna remains stable within a wide beam of 100° covering the whole GNSS bands, with phase center variation retained below 5°.

New EBG of CSRR with lumped capacitors applied to oscillator harmonics suppression

In this article, a compact electromagnetic band-gap (EBG) structure is presented to reject harmonics of a crystal oscillator in the power distribution network. Compared to traditional EBG structures of complementary split ring resonator (CSRR), the proposed CSRR adding lumped capacitors (LC-CSRR) provides a higher rejection-performance at the series self-resonant frequency of the lumped capacitors. A four-layer printed circuit board is designed and fabricated to measure the S-parameters of the proposed EBG structure, and a harmonics power testing board is presented to measure rejection performance of the proposed EBG structure. The measured results show that the proposed EBG obtains an attenuation of 60 dB over the whole range of global navigation satellite system band. By inserting the proposed EBG structure of LC-CSRR, we measure that the harmonics powers can be decreased by 28.8 dB between the input and output of the EBG.

Surface Impedance Engineered Low-Profile Dual-Band Grooved-Dielectric Choke Ring for GNSS Applications

A novel low-profile grooved-dielectric choke ring with dual-band surface impedance resonance is proposed and experimentally demonstrated. The proposed structure is designed by engineering the surface impedance of a dielectric-based choke ring to introduce two resonant frequencies around the global navigation satellite system (GNSS) bands of L2 (1227.60 MHz) and L1 (1575.42 MHz). This provides capacitive surface impedances around both bands simultaneously, which is required for efficient surface wave suppression for higher multipath rejection performance. To demonstrate the proposed principle of surface impedance engineering, an in-house choke ring prototype of the proposed design is tested with the widely used Dorne and Margolin antenna. A high multipath rejection in both GNSS bands is experimentally confirmed with comparable performances to an otherwise bulky, heavy, and expensive conventional metallic choke ring.

A Low Profile, Dual-band, Dual Polarized Antenna for Indoor/Outdoor Wearable Application

A planar, low-profile, dual-band and dual-polarized antenna on a semi-flex substrate is proposed in this paper. The antenna is fabricated on Rogers substrate with a thickness of 3.04 mm and sized at $70.4 \times 76.14 \times 3.11$ mm3 ( $0.37\lambda _{0} \times 0.40\lambda _{0}\times 0.016 \lambda _{0}$ ) only. The circular polarization property is enabled in the global navigation satellite system (GNSS) L1/E1 (lower) band by introducing a complementary split ring resonator on the antenna patch. Meanwhile, the antenna operates in the second (upper) 2.45 GHz WLAN band is enabled by etching a U-shaped slot on its ground plane. This simultaneous, dual-band and dual-polarized operation enables the proposed antenna to be applied in the indoor/outdoor wearable application. To isolate the antenna against the influence of the human body, a multiband artificial magnetic conductor (AMC) plane is added on the reverse side of the dual-band radiator. Comparison of the antenna without AMC in free space and when evaluated on the chest of a human body backed by AMC showed improved gain; from 3–5.1 dBi in the lower band, and from 1.53–5.03 dBi in the upper band. Besides that, the front-to-back ratio of the AMC backed monopole antenna also improved from 11–21.88 dB and from 2.5–24.5 dB in the GNSS and WLAN bands, respectively. Next, the specific absorption rate (SAR) of the monopole antenna with and without the AMC plane is assessed. Evaluation results indicate that the maximum SAR value decreased by up to 89.45% in comparison with the antenna without AMC in the lower band. This indicates the effectiveness of the AMC array in increasing gain and FBR, besides reducing EM absorption in the human body.

Flexible thin antenna solution for wearable ankle bracelet applications with GNSS and BLE connectivity

AbstractA thin antenna structure to operate in GNSS (Global Navigation Satellite System) and BLE (Bluetooth Low Energy) communication standards is proposed. The antenna was built on a flexible and thin Kapton material inserted between 2 layers of bovine leather, suitable for limited weight and slim ankle bracelet designs. Proposed antenna structure consist of 2 opposed planar inverted F antennas modified using matching stubs, sharing the same substrate and ground plane, with total size of 96.8 × 35 × 4.14 mm. The ground plane area of the antenna can be used for electronic circuit and battery placement. The antenna structure operates in the following specific 4 bands: BeiDou (1561 MHz), GPS (1575 MHz), GLONASS (1602 MHz), and BLE (2400 MHz). The antenna exhibited great agreement between electromagnetic simulations in ADS Momentum and measurements performed into 3D anechoic chamber with anthropomorphic leg‐foot model from Speag. The antenna peak gain is approximately −1.8 dBi for GNSS bands and −2.0 dBi for BLE.

Multiband Printed Loop Mobile Phone Antenna for LTE/WWAN/GNSS Application

A multiband printed loop mobile phone antenna for LTE/WWAN/GNSS application is presented. It covers seven communication bands (VSWR < 3) and GNSS band (VSWR < 1.5). The so-called GNSS (global navigation satellite system) band includes COMPASS, GALILEO, GPS, and GLONASS. From the analysis of the structure, the coupled-fed antenna mainly consists of three parts: the feeding strip, shorted strip, and U-shaped parasitic coupling strip. The proposed antenna works in three resonant modes, respectively, at 860 MHz (0.25λ), 1620 MHz (0.5λ), and 2620 MHz (1λ). A solution is provided, by which the navigation antenna can be integrated into the communication main antenna to save space. The antenna not only can work in GSM850/900/1800/1900/UMTS2100/LTE2300/2500 bands but also covers the world’s four major navigation systems. Moreover, the proposed antenna can be easily printed on the circuit board without loading any lumped element and only occupies a small volume of 18 × 32 × 3 mm3, which is suitable for smartphone application. In addition, the redundant design of multinavigation system is quite favorable for the elimination of errors or shadow area caused by single navigation system, especially for outdoor investigation, national security, and so on.

Triple-Band Antenna With Shorted Annular Ring for High-Precision GNSS Applications

In this letter, we propose a triple-band stacked circular-polarized patch antenna design that covers all Global Navigation Satellite System (GNSS) bands (1.166-1.289, 1.554-1.612, and 2.482-2.502 GHz). The mutual couplings among three bands decrease the performance of radiant efficiency. To address this problem, we adopt two shorted annular rings, which are formed with circular array of via. Furthermore, to increase the impedance band at low L-band, we adopt a four-L-probe feeding configuration. Compared to other reported GNSS antennas, the proposed antenna covers all GNSS band, possesses much better gain pattern and phase center performance, and is suitable for high-precision GNSS applications.

Investigation on the effect of strong out-of-band signals on global navigation satellite systems receivers

The mitigation of radio frequency interference (RFI) has a fundamental role in global navigation satellite system (GNSS) applications, especially when a high level of availability is required. Several electromagnetic sources, in fact, might degrade the performance of the global positioning system (GPS) and Galileo receivers, and their effects can be either in-band (i.e., secondary harmonics generated by transmitters of other communication systems due to non-linearity distortions) or out-of-band (i.e., strong signals that occupy frequency bandwidths very close to GNSS bands). We investigated the effects of real out-of-band signals on GNSS receivers and analyzed the impact on the overall receiver chain in order to evaluate the impact of the interference source. In particular, the analysis focuses on the spectrum at the front-end output, on the automatic gain control (AGC) behavior, as well as on the digital processing stages (signal acquisition and tracking) at the analog digital converter (ADC) output. This study refers to several experiments and data collections performed in interfered areas of downtown Torino (Italy). The obtained results underline how digital/analog TV transmissions represent a potential interference source for GNSS applications and might be critical for the safety of life services.