Receiver Antenna Research Articles

Optimasi Waktu Akuisisi Data Satelit Noaa18 Menggunakan Jaringan Syaraf Tiruan Backpropagation

Earth stations are built to monitor the presence of satellites starting from satellite data, monitoring satellites, and carry out orders and corrections if needed. On the earth station there is a satellite data receiving antenna, the more elevation angle of the current satellite data receiver antenna can affect the time duration of the satellite data. The purpose of this research is to apply the Artificial Neural Network (ANN) method to design a time optimization system for satellite data at the LAPAN Pekayon earth station, East Jakarta. The data used as input is the elevation angle. The benefit of this research is expected to make it easier for operators and technicians to measure the time optimization of satellite data at earth stations. The best training results with learning rate = 0.2, error = 0.0001, max. epoch = 100000, neuron hidden layer = 15. The MSE value obtained is 0.0001 reaching the goal at epoch 68810. Regret the training / training reverse sequence reaches 0.99878. The best test result is to use learning speed 0.2 hidden layer neurons 15 comparison of training data = 54 and test data = 18. The accurate result is exactly the same as the specified error, namely 0.0001. The difference in the average target duration is 3 seconds compared to the ANN target. Artificial Neural Network (ANN) with the back propagation method of training function gradient descent (traingd), was successfully used to an optimization system for satellite data acquisition time at earth stations.

A phase-difference-of-arrival assisted ultra-wideband positioning method for elderly care

Ultra-wideband (UWB) is a promising mean for elderly care in line-of-sight (LOS) environments. One major limitation of UWB-based localization is the non-line-of-sight (NLOS) for signals caused by severe environments, resulting in dramatic performance degradation. Although many NLOS identification and compensation methods in presence of complex indoor environments have been proposed, they are only applicable to specific environments or require enough LOS BSs to detect NLOS measurements. To address these issues comprehensively, we propose a phase-difference-of-arrival (PDOA) assisted UWB positioning method (PDOA-UWB) for elderly care in this paper, which consists of three steps: (1) coarse localization, calculated from PDOA measurements at multiple receiver antennas of UWB base stations (BSs), (2) LOS BSs selection, and (3) fine localization through a convex regression estimator. Our method is simple and effective and can be used in various practical environments without prior information about the NLOS error. Overall experimental results verify that PDOA-UWB can achieve better positioning accuracy than existing methods in severe NLOS environments.

C-Band Telemetry of Insect Pollinators Using a Miniature Transmitter and a Self-Piloted Drone

A battery-less 5.8-GHz transmitter (TX), compact and lightweight enough to enable flight of $\sim 90$ mg honeybees and free roaming of bumblebees within their nest, was developed. The TX was coupled to a compact phased-array antenna receiver to achieve angle of arrival (AOA) estimation and bee localization through a received signal strength indicator approach (RSSI). The receiver was integrated into a commercial unmanned aerial vehicle (UAV) to support autonomous position updates based on the AOA estimates and a software development kit. A simple model predicting the system detection range was finally developed and is herein discussed. Our experimental results provide proof of concept toward autonomous tracking of tagged bees both in open air and in polytunnel settings.

Triple-Resonance Chipless RFID Tag With Dual Circularly-Polarized Wideband Reader Antenna for Wirelessly Differentiating Liquid

To wirelessly differentiate specified liquid samples, this article presents a radio-frequency identification (RFID) front-end including wideband reader antenna with chipless tag. The proposed reader antenna employs left-handed circularly-polarized (LHCP) antenna for transmitter (Tx) and right-handed circularly-polarized (RHCP) antenna for receiver (Rx), to improve the Tx-Rx isolation and also liberate the orientation and polarization of chipless tags. This dual circularly-polarized (dual-CP) configuration also features wide bandwidths of impedance and axial ratio, by using sequentially-rotated structure. Moreover, the proposed chipless tag has three resonances, among them, one independent resonance provides a lookup table for fast and easy identification, and another two resonances can be used to reconfirm the identification results. For validation, dual-CP reader antenna array and chipless tag are numerically optimized, experimentally measured, and also in-vivo demonstrated to wirelessly differentiate liquid samples.

A W-Band Single-Antenna FMCW Radar Transceiver With Adaptive Leakage Cancellation

This article presents a leakage cancellation architecture for single-antenna frequency-modulated continuous-wave (FMCW) radars at W-band. A shared antenna for transmitter (TX) and receiver (RX) can substantially reduce the form factor, cost, and complexity of radar modules. Due to the simultaneous operation of the TX and RX in FMCW radars, employing a shared antenna will, however, significantly increase TX-to-RX leakage, resulting in RX saturation and desensitization. Our proposed cancellation scheme employs analog feedback to confine the TX leakage right at the RX input port, and thus, relieves the ongoing RX chain from saturation. The proposed single-antenna transceiver (TRX) prototype was fabricated in 65-nm CMOS technology with a die area of 1 mm2. The output power of 2 dBm was achieved for the TX in a frequency range of 80–84 GHz. In addition, a conversion gain and noise figure of 45 and 15 dB was measured for the RX in the presence of the TX signal via a shared antenna port. TX-to-RX isolation of more than 45 dB was achieved in the operating W-band. The chip consumes 108 mW (80.5 mW for the TX and 27.5 mW for the RX) from a 1.2-V supply voltage. Moreover, the functionality of the single-antenna radar operation was verified by connecting the chip to an on -printed circuit board (PCB) $4 \times 8$ patch antenna array with a simulated gain of 15 dBi, implemented on RO3003 Rogers material. Using the single-antenna radar module as a demo system, a $40\times 50$ cm2 rectangular metallic plate was detected at a distance up to 19 m.

Analysis and design of MIMO indoor communication system using terahertz patch antenna based on photonic crystal with graphene

In this study, a multiple input/multiple output (MIMO) indoor communication system was developed using microstrip antennae based on a photonic crystal substrate, where the graphene load operated in the terahertz band. First, the characteristics of graphene were analyzed by determining the operating modes related to the chemical potential of graphene. Next, three MIMO antennae were designed and analyzed using homogenous, photonic crystals, or optimized photonic crystal substrates, and by utilizing a planted graphene load. The results obtained in CST simulations indicated enhancement of the bandwidth as the frequency reached 356 GHz and an improvement in the gain was also achieved. An indoor communication environment based on the terahertz band was then studied and compared with previously proposed methods. The path loss and reflection loss were analyzed for single input/single output, single input/multiple output, multiple input/single output, and MIMO systems. The geometrical parameters of the indoor environment operating in the terahertz band were investigated. Finally, an interesting enhancement of the channel capacity was achieved using the aforementioned design for MIMO antennae. Moreover, the extra channel capacity could be modified in the proposed system by manipulating the spacing between the transmission antennae or receiver antennae, or the distance between the transmission and receiver antennae.

Optimization of Log-Periodic TV Reception Antenna with UHF Mobile Communications Band Rejection

The coexistence of TV broadcasting and mobile services causes interference that leads to poor quality-of-service for TV consumers. Solutions usually found in the market involve external band-stop filters along with TV reception log-periodic and Yagi-Uda antennas. This paper presents a log-periodic antenna design without additional filtering that serves as a lower cost alternative to avoid interference from mobile services into the UHF TV. The proposed antenna operates in the UHF TV band (470–790 MHz-passband) and rejects the 800 MHz and 900 MHz bands (stopband) of 4G/LTE-800 and GSM900 services, respectively. Matching to 50 Ohms is very satisfactory in the passband with values of S11 below −12 dB. Furthermore, the antenna is highly directive with a realized gain of approximately 8 dBi and a front-to-back ratio greater than 20 dB.

Research on Single Antenna Co-frequency Mixed Signal Separation Based on Improved EFICA Algorithm

Signal separation under the condition of single antenna reception is a process of estimating the source signal component by using one-dimensional observation signal vector. Under the condition of single antenna receiving the same-frequency mixed signal, in view of the problem that the stability of the EFICA algorithm will be affected by the selection of a random initial iterative matrix, it is proposed to use the steepest descent method to select a suitable iterative initial matrix to improve the EFICA algorithm. An experimental comparison between the EFICA algorithm and the EFICA improved algorithm is presented. The simulation results show that the improved EFICA algorithm can achieve a better separation effect for the separation of mixed signals at the same frequency.

Active Feed Tuning for Excitation Symmetry in Simultaneous Transmit and Receive Antennas

We present an actively tuned balun to enable simultaneous transmit and receive (STAR) antennas to achieve greater isolation. Specifically, for the first time, we propose placing a chip into the antenna feed to control the amplitude of the current density. Nearly perfect balance of the feed currents enables STAR antennas to maintain strong isolation despite unpredictable fabrication imperfections. Two identical prototypes were fabricated for comparison, one passive and the other with active tuning inserted. Measurements demonstrate a minimum isolation of 42 dB across a 250 MHz bandwidth, representing an 11 dB improvement over the passive case. This is the best reported transmit/receive isolation enhancement to date. Further, this novel tuning method is significant because it enables STAR antennas with low-cost substrates, such as FR-4, to achieve greater isolation than passive designs. Notably, the balun was tuned across 1.68–1.93 GHz, part of the Federal Communication Commission's AWS-3 spectrum auction. Measurements show good comparison with simulation.

Characterization and mitigation of multipath fading on multi-frequency GNSS signals in urban environment

The global navigation satellite systems (GNSS) receiver is likely to experience performance degradation in the presence of multipath interferences in indoor and urban canyon environments. There will be multiple reflected signals arriving at the receiver antenna from different paths and directions regarding the different locations of the nearby constructions, causing significant fluctuations and distortions on the amplitude and phase of the direct signals. This is the so-called multipath fading effects and usually exhibit with the random features of temporal, spatial, and frequency diversity across the signal bands. To have a better understanding of the multipath fading effects, a live test was conducted near Lujiazui CBD area in Shanghai. The collected data were processed to characterize the signal attenuations and phase fluctuations on multi-frequency GNSS signals via the detrend code delay, carrier phase, and navigation bit errors. The resulting scintillation index on amplitude, code delay, and carrier phase, e.g., S4, $${\sigma }_{\varphi }$$ and $${\sigma }_{\tau }$$ can be calculated. Based on these multipath features, the inter-frequency aiding strategy will be utilized for the multipath mitigations in the multi-frequency tracking loop design. The results demonstrate the effectiveness of the multi-frequency tracking algorithm in the urban environment.

Two methods to determine scale-independent GPS PCOs and GNSS-based terrestrial scale: comparison and cross-check

The GPS satellite transmitter antenna phase center offsets (PCOs) can be estimated in a global adjustment by constraining the ground station coordinates to the current International Terrestrial Reference Frame (ITRF). Therefore, the derived PCO values rest on the terrestrial scale parameter of the frame. Consequently, the PCO values transfer this scale to any subsequent GNSS solution. A method to derive scale-independent PCOs without introducing the terrestrial scale of the frame is the prerequisite to derive an independent GNSS scale factor that can contribute to the datum definition of the next ITRF realization. By fixing the Galileo satellite transmitter antenna PCOs to the ground calibrated values from the released metadata, the GPS satellite PCOs in the z-direction (z-PCO) and a GNSS-based terrestrial scale parameter can be determined in GPS + Galileo processing. An alternative method is based on the gravitational constraint on low earth orbiters (LEOs) in the integrated processing of GPS and LEOs. We determine the GPS z-PCO and the GNSS-based scale using both methods by including the current constellation of Galileo and the three LEOs of the Swarm mission. For the first time, direct comparison and cross-check of the two methods are performed. They provide mean GPS z-PCO corrections of - 186 pm 25 mm and - 221 pm 37 mm with respect to the IGS values and + 1.55 pm 0.22 ppb (parts per billion) and + 1.72 pm 0.31 in the terrestrial scale with respect to the IGS14 reference frame. The results of both methods agree with each other with only small differences. Due to the larger number of Galileo observations, the Galileo-PCO-fixed method leads to more precise and stable results. In the joint processing of GPS + Galileo + Swarm in which both methods are applied, the constraint on Galileo dominates the results. We discuss and analyze how fixing either the Galileo transmitter antenna z-PCO or the Swarm receiver antenna z-PCO in the combined GPS + Galileo + Swarm processing propagates to the respective freely estimated z-PCO of Swarm and Galileo.

Opportunistic Access Point Selection for Mobile Edge Computing Networks

In this paper, we investigate a mobile edge computing (MEC) network with two computational access points (CAPs), where the source is equipped with multiple antennas and it has some computational tasks to be accomplished by the CAPs through Nakagami-m distributed wireless links. Since the MEC network involves both communication and computation, we first define the outage probability by taking into account the joint impact of latency and energy consumption. From this new definition, we then employ receiver antenna selection (RAS) or maximal ratio combining (MRC) at the receiver, and apply selection combining (SC) or switch-and-stay combining (SSC) protocol to choose a CAP to accomplish the computational task from the source. For both protocols along with the RAS and MRC, we further analyze the network performance by deriving new and easy-to-use analytical expressions for the outage probability over Nakagami-m fading channels, and study the impact of the network parameters on the outage performance. Furthermore, we provide the asymptotic outage probability in the low regime of noise power, from which we obtain some important insights on the system design. Finally, simulations and numerical results are demonstrated to verify the effectiveness of the proposed approach. It is shown that the number of transmit antenna and Nakagami parameter can help reduce the latency and energy consumption effectively, and the SSC protocol can achieve the same performance as the SC protocol with proper switching thresholds of latency and energy consumption.

Intercomparison of Sonde, WRF/CAMx and Satellite Sounder Profile Data for the Paso Del Norte Region

The Paso Del Norte (PdN) region comprises the city of El Paso, TX, Ciudad Juarez, Mexico, and some neighboring cities in the state of New Mexico. Developing a regional weather model for this specific region has always been challenging due to its complex terrain. To obtain more accurate weather and pollution forecasting for the PdN region, the results of the downscaled WRF (Weather Research and Forecast) model were intercompared with meteorological satellite data, with ground and radiosonde dataset. In addition, it is critical to analyze the distributions of ozone concentrations to better understand atmospheric aerosol concentrations and predict them both more accurately. Hence, in this study the ozone results of CAMx (Comprehensive Air Quality Model with Extensions) were extensively intercompared with ozonesonde data. The radiosonde/ozonesonde data were obtained throughout a campaign conducted during the summer of 2017 in the PdN region. Different meteorological variables such as temperature, pressure, relative humidity, wind speed, and ozone concentrations were used for comparison at several locations in the PdN region. The TCEQ (Texas Commission of Environment Quality) data from different CAMS (Continuous Ambient Monitoring Stations) were used for ground data intercomparison with the WRF results. The meteorological satellite sounding data were retrieved using an in-house satellite antenna receiver. The results of this research paper will not only provide better pollution forecasting capability for the PdN region but also for other regions with similar topography and terrain.

Quantifying errors in GNSS antenna calibrations

We evaluated the performance of GNSS absolute antenna calibrations and its impact on accurate positioning with a new assessment method that combines inter-antenna differentials and laser tracker measurements. We thus separated the calibration method contributions from those attainable by various geometric constraints and produced corrections for the calibrations. We investigated antennas calibrated by two IGS-approved institutions and in the worst case found the calibration’s contribution to the vertical component being in excess of 1 cm on the ionosphere-free frequency combination L3. In relation to nearby objects, we gauge the 1sigma accuracies of our method to determine the antenna phase centers within pm ,0.38 mm on L1 and within pm ,0.62 mm on L3, the latter applicable to global frame determinations where atmospheric influence cannot be neglected. In addition to antenna calibration corrections, the results can be used with an equivalent tracker combination to determine the phase centers of as-installed individual receiver antennas at system critical sites to the same level without compromising the permanent installations.

A Precoding Aided Space Domain Index Modulation Scheme for Downlink Multiuser MIMO Systems

In this correspondence, we propose a space domain index modulation (IM) scheme for the downlink of multiuser multiple-input multiple-output (MU-MIMO) systems. Instead of the most common approach where spatial bits select active receiver antennas, in the presented scheme the spatial information is mapped onto the transmitter side. This allows IM to better exploit large dimensional antenna settings which are typically easier to deploy at the base station. In order to mitigate inter-user interference and allow single user detection, a precoder is adopted at the BS. Furthermore, two alternative enhanced signal construction methods are proposed for minimizing the transmitted power or enable an implementation with a reduced number of RF chains. Simulation results for different scenarios show that the proposed approach can be an attractive alternative to conventional precoded MU-MIMO.

Microwave Holographic Imaging of Nonmetallic Concentric Pipes

Recently, nonmetallic materials, which are resilient to corrosion, low cost, and lightweight, have been exploited in many industrial sectors such as oil and gas field. A common application of them is in the form of pipes. Despite the advantages, these pipes can be damaged by delamination, defects, holes, and erosion, which may lead to major production failures or even environmental catastrophes. To prevent these issues, nondestructive testing (NDT) of these pipes is required to replace these components in a timely manner. Due to the fact that the traditional NDT methods are mostly effective for metallic pipes, microwave holographic imaging is proposed for inspection of multiple concentric nonmetallic pipes. Besides, standardized minimum norm (SMN) is used to mitigate the depth biasing problem in the proposed imaging technique. To reduce the complexity of the imaging system, we aim at using the narrowest possible frequency band using an array of receiver antennas. The performance of the proposed NDT method is validated through simulation and experimental data in two scenarios including the antennas placed outside the pipes and inside the pipes.

Impact of Using GPS L2 Receiver Antenna Corrections for the Galileo E5a Frequency on Position Estimates.

Knowledge of Global Navigation Satellite System (GNSS) antenna phase center variations plays a key role in precise positioning. Proper modeling is achieved by accessing antenna phase center corrections, which are determined in the calibration process. For most receiver antenna types, the International GNSS Service provides such corrections for two GPS and GLONASS carrier signals. In the case of Galileo, access to phase center corrections is difficult; only antennas calibrated in the anechoic chambers have available corrections for Galileo frequencies. Hence, in many of the studies, GPS-dedicated corrections are used for these Galileo frequencies. Differential analysis was conducted in this study to evaluate the impact of such change. In total, 25 stations belonging to the EUREF Permanent Network and equipped with individual calibrated antennas were the subject of this research. The results for both the absolute and relative positioning methods are clear: using GPS L2 corrections for Galileo E5a frequency causes a bias in the estimated height of almost 8 mm. For the horizontal component, a significant difference can be noticed for only one type of antenna.

Smart Devices Performance With SSK-BPSK Modulation and Energy Harvesting in Smart Cities

In this letter, we analyze smart devices' performance in smart cities using radio frequency (RF) based energy harvesting. In a smart city, smart electronics devices play an important role in communication between the devices and centralized access point (AP). Here, we have considered dynamic space shift keying (SSK) and binary phase-shift keying (BPSK) modulation for communication. A single radio frequency (RF) chain of the transmitter dynamically changes the modulation scheme between SSK and BPSK. Based on one-bit feedback from the receiver antenna, the modulation scheme is selected, and this feedback path can be used for energy harvesting. Using multi-user selection combining, the average bit error probability (ABEP) performance of smart devices with wireless power communication network (WPCN) is derived in closed form over Saleh-Valenzuela (S-V) channel.

Viterbi Decoder to Resolve Angular Ambiguity in Digital Beamforming With Widely Spaced Radar Front Ends

This article introduces a precise radar-based direction-of-arrival measurement system using a Viterbi decoder. Based on the frequency-modulated continuous-wave principle, the presented method employs both the frequency difference and the round-trip phase difference of the radio wave signal impinging at two widely spaced receiving antennas, thereby accomplishing highly accurate and absolute measurements of the direction-of-arrival. In order to resolve angular ambiguity, which is inherently caused by the $2 \pi $ ambiguity in phase measurement, the proposed Viterbi decoder determines the most likely sequence of direction-of-arrivals of the impinging radio wave signals. For proof of concept, experiments based on a 77 GHz radar unit equipped with one transmitting and two widely spaced receiving antennas were carried out. The measurement results show that angular ambiguity can be resolved by the presented Viterbi decoder since absolute, accurate, and repeatable direction-of-arrival estimates were obtained, even for receiver antenna spacings significantly larger than the signal wavelength.

Energy-Efficient Analog Combiner Design Using Low-Resolution Phase Shifters and Antenna Selection for mmWave D2D Communications

This study investigates the use of an analog combiner comprising low -resolution phase shifters (PSs) to suppress interference from other devices and improve the received signal power of interest in millimeter-wave device-to-device networks simultaneously. Unlike typical analog combining architectures with PS numbers equaling the number of receiver antennas, the number of PSs in this study is less than that of receiver antennas; this feature saves on equipment costs and improves power efficiency. We jointly optimize the receiver antenna selection and analog combiner design with low-resolution PSs to maximize the spectral efficiency of the resultant device. Because the formulated joint optimization problem is non-convex, we propose a probabilistic evolutionary optimization algorithm with an explicit expression for learning the tilting parameters of the designed sampling distribution. Simulation results demonstrate the excellent performance of the proposed algorithm compared with the semidefinite relaxation approach in terms of spectral and energy efficiency.