A Tiny 2.4 GHz Monopole Water Antenna

We designed, fabricated, and evaluated a monopole water antenna (WA) filled with pure water. A 2.4 GHz patch antenna (PA) was used for measurement comparison, and the current density distribution and 3D field strength radiation distribution and reflection coefficient of the PA had a fundamental mode and a higher-order mode at 3.5 GHz, whose polarization was 90 degrees different. The 2.4 GHz monopole WA could receive only the fundamental mode of the PA. The 3.5 GHz WA could receive the higher-order mode of the PA by rotating the WA by 90 degrees. The transmission coefficient of the 2.4 GHz WA decreased with the square of the spacing, similar to the spatial propagation characteristics of electromagnetic waves. Almost the same results could be expected if planar or three-dimensional antennas were used instead of monopole electrodes

Exploiting W. Ellison model for seawater communication at gigahertz frequencies based on world ocean atlas data

Electromagnetic (EM) waves used to send signals under seawater are normally restricted to low frequencies (f) because of sudden exponential increases of attenuation (α) at higher f. The mathematics of EM wave propagation in seawater demonstrate dependence on relative permeability (μr), relative permittivity (εr), conductivity (σ), and f of transmission. Estimation of εr and σ based on the W. Ellison interpolation model was performed for averaged real‐time data of temperature (T) and salinity (S) from 1955 to 2012 for all oceans with 41088 latitude/longitude points and 101 depth points up to 5500 m. Estimation of parameters such as real and imaginary parts of εr, εr′, εr″, σ, loss tangent (tan δ), propagation velocity (Vp), phase constant (β), and α contributes to absorption loss (La) for seawater channels carried out by using normal distribution fit in the 3 GHz–40 GHz f range. We also estimated total path loss (LPL) in seawater for given transmission power Pt and antenna (dipole) gain. MATLAB is the simulation tool used for analysis

AN INVESTIGATION OF SHORT RANGE ELECTROMAGNETIC WAVE COMMUNICATION FOR UNDERWATER ENVIRONMENTAL MONITORING UTILISING A SENSOR NETWORK PLATFORM

Current state of the art water communications systems rely on optical and acoustic propagation. But these have underperformed in many applications. Wireless Sensor Network (WSN) using radio communication underwater is state of the art. The frequency of operation and the antenna are the big challenges that if unlocked, will present many advantages. The aim of this research is to investigate short range electromagnetic wave communication for underwater environmental monitoring utilising a sensor network platform. Theoretical study and preliminary experiments have confirmed that ISM (industrial, scientific and medical) band at 433MHz was suitable for potable and freshwater communication. Traditional antennas have been constructed, tested and modelled in a High Frequency Simulator Structure (HFSS) but were found unsuitable for use underwater. A 433MHz bowtie antenna was modelled in HFSS and shown to perform well in both air and potable water without any matching circuit. The antenna was prototyped on a printed circuit board, waterproofed and tested successfully in a tank. Furthermore to eliminate RF crosstalk, a battery powered wireless transmitter that generated a carrier signal at 433MHz, was used successfully in the laboratory tank, and during experiments that were repeated in freshwater in Liverpool Stanley Canal. This range, in excess of 5m, was large enough to combine the bowtie antenna with off the shelf, low power transceivers operating at the 433MHz, and specific sensors to form a WSN for potable and freshwater applications. The contribution to knowledge is the experimental demonstration of reliable communication at 433MHz using a broadband antenna which unlocks the potential of underwater WSN applications, including applications in water quality measurement, using radio communication

Compact elliptical UWB antenna for underwater wireless communications

The increasing needs of free licensed frequency bands like Industrial, Scientific, and Medical (ISM), Wireless Local Area Network (WLAN), and 5G for underwater communications required more bandwidth (BW) with higher data transferring rate. Microwaves produce a higher transferring rate of data, and their associated devices are smaller in comparison with sonar and ultrasonic. Thus, transceivers should have broad BW to cover more of a frequency band, especially from ultra-wideband (UWB) systems, which show potential outcomes. However, previous designs of similar work for underwater communications were very complicated, uneasy to fabricate, and large. Therefore, to overcome these shortcomings, a novel compact elliptical UWB antenna is designed to resonate from 1.3 to 7.2 GHz. It is invented from a polytetrafluoroethylene (PTFE) layer with a dielectric constant of 2.55 mm and a thickness of 0.8 mm. The proposed antenna shows higher gain and radiation efficiency and stability throughout the working band when compared to recent similarly reported designs, even at a smaller size. The characteristics of the functioning antenna are investigated through fluid mediums of fresh-water, seawater, distilled water, and Debye model water. Later, its channel capacity, bit rate error, and data rate are evaluated. The results demonstrated that the antenna offers compact, easier fabrication with better UWB characteristics for underwater 5G communications

Signals in the Soil: An Introduction to Wireless Underground Communications

In this chapter, wireless underground (UG) communications are introduced. A detailed overview of WUC is given. A comprehensive review of research challenges in WUC is presented. The evolution of underground wireless is also discussed. Moreover, different component of UG communications is wireless. The WUC system architecture is explained with a detailed discussion of the anatomy of an underground mote. The examples of UG wireless communication systems are explored. Furthermore, the differences of UG wireless and over-the-air wireless are debated. Different types of wireless underground channel (e.g., In-Soil, Soil-to-Air, and Air-to-Soil) are reported as well

A Survey on Subsurface Signal Propagation

Wireless Underground Communication (WUC) is an emerging field that is being developed continuously. It provides secure mechanism of deploying nodes underground which shields them from any outside temperament or harsh weather conditions. This paper works towards introducing WUC and give a detail overview of WUC. It discusses system architecture of WUC along with the anatomy of the underground sensor motes deployed in WUC systems. It also compares Over-the-Air and Underground and highlights the major differences between the both type of channels. Since, UG communication is an evolving field, this paper also presents the evolution of the field along with the components and example UG wireless communication systems. Finally, the current research challenges of the system are presented for further improvement of the WUCs