Conformal Load-Bearing Antenna Structures—Mechanical Loading Considerations

One of the important functions of antennas is to facilitate wireless communication. The IEEE 802.11 is part of the IEEE802 set of local area network technical standards, and specifies the media access control and physical layer protocols for implementing wireless local area network computer communication. The network physical layer protocol with a centre frequency of 2.4 GHz has a bandwidth of 22 MHz. A conformal load-bearing antenna structure (CLAS) facilitating this communication band that is tuned to 2.4 GHz must remain within this bandwidth. The aim of this paper is to investigate the effects of mechanical loading imposed on a load-bearing patch antenna with respect to its ability to remain within the specified bandwidth. The mechanical loading configurations considered include tensile, biaxial, and twisting. This paper will also report on the response of the antenna patch to the presence of a disbond between the metallised antenna and its substrate, which can arise due to fabrication anomalies and operational usage. This numerical work will assist in the design of experimental testing of the mechanical and electromagnetic properties of an embedded CLAS, which will ultimately be used to inform selection of appropriate regions to place patch antennas on load-bearing deformable surfaces.

A compact high gain wideband millimeter wave 1 × 2 array antenna for 26/28 GHz 5G applications

Purpose This paper aims to present the design, fabrication and analysis of a wideband, enhanced gain 1 × 2 patch antenna array with a simple profile structure to meet the desired antenna traits, such as wide bandwidth, high gain and directional patterns expected for the upcoming fifth-generation (5G) wireless applications in the millimeter wave band. To enhance these parameters (bandwidth and gain), a new antenna geometry by using a T-junction power divider is presented. Design/methodology/approach The theory behind this paper is connected with advancements in the 5G communications related to antennas. The methodology used in this work is to design a high gain array antenna and to identify the best possible power divider to deliver the power in an optimized way. The design methodology adopts several steps like the selection of proper substrate material as per the design specification, size of the antenna as per the frequency of operation and application-specific environment condition. The simulation has been performed on the designed antenna in the electromagnetic simulation tool (high-frequency structure simulator [HFSS]), and optimization has been done with parametric analysis, and then the final array antenna model is proposed. The proposed array contains 2-patch elements excited by one port adapted to 50 Ω through a T-junction power divider. The 1 × 2 array configuration with the suggested geometry helps to improve the overall gain of the antenna, and the implementation of the T-junction power divider provides enhanced bandwidth. The proposed array designed using a 1.6 mm thick flame retardant substrate occupies a compact area of 14 × 12.14 mm2. Findings The prototype of the array antenna is fabricated and measured to validate the design concept. A good agreement has been reached between the measured and simulated antenna parameters. The measured results confirm its wideband and high gain characteristics, covering 24.77–28.80 GHz for S11= –10 dB with a peak gain of about 15.16 dB at 27.65 GHz. Originality/value The proposed antenna covers the bandwidth requirements of the 26 GHz n258 band (24.25–27.50 GHz) to be deployed in the UK and Europe. The suggested antenna structure also covers the federal communications commission (FCC)-regulated 28 GHz n261 band (27.5–28.35 GHz) to be deployed in America and Canada. The low profile, compact size, simple structure, wide bandwidth, high gain and desired directional radiation patterns confirm the applicability of the suggested array antenna for the upcoming 5 G wireless systems.

Metasurface Superstrate Beam Steering Antenna with AMC for 5G/WiMAX/WLAN Applications

A beam-steering antenna based on non-uniform metasurface superstrate and AMC, operating at 3.5 GHz, is presented. The antenna can steer the beam along θ = -18° and 18° with the superstrate and along θ = 0° in the absence of the superstrate with almost zero scan loss. Antenna structure consists of a top layer of non-uniform metasurface superstrate made of a 20 × 20 grid of electrically-small square-shaped metallic pixels while the bottom part consists of AMC with a grid of 5 × 5 pixels. The radiating element, CPW-fed monopole antenna, is placed between AMC and superstrate. The fabricated prototype shows desired beam steering in directions of θ = -18°, 0°, and 18° while maintaining uniform realized gain of 5.5 dB and matches well with simulations.

High-Isolation UWB MIMO Antenna with Multiple X-Shaped Stubs Loaded between Ground Planes

A miniaturized ultra-wideband multiple-input multiple-output (UWB MIMO) two-port antenna with high isolation based on FR4 is designed in this article. The size of the antenna is only 18 × 28 × 1.6 mm3. The MIMO antenna consists of two identical antenna elements symmetrically placed on the same dielectric substrate in opposite directions. By loading three crossed X-shaped stubs between two unconnected ground planes, high isolation and good impedance matching are achieved. The working frequency band measured by this UWB MIMO antenna is 1.9–14 GHz, and the isolation is kept above 20.2 dB in the whole analysis frequency band. Good radiation characteristics as well as envelope correlation coefficient (ECC, <0.09), mean effective gain (MEG), and channel capacity loss (CCL) in the passband meet the requirements of the application, which can be applied to the UWB wireless communication system. To verify the applicability of the proposed method for enhancing the isolation between antenna elements, the two-port antenna structure was extended to a four-port antenna structure. In the case of loading the X-shaped stubs to connect to the ground plane, the isolation of the antenna is maintained above 15.5 dB within 1.7–14 GHz.

The pointing model of 4.5-m small radio telescope at NARIT

The efficiency of a radio telescope decisively depends on its pointing accuracy. Telescope’s pointing model (PM) contains repeatable errors due to the antenna control system’s imperfections, which can be corrected during observation. The 4.5m Small Radio Telescope (SRT’s) has been developed for education and experiments at Astropark, National Astronomical Research Institute of Thailand (NARIT), Chiang Mai (18°N 51’ 5” and 98°E 57’ 27”). We have implemented a 10-cm optical camera system installed on the SRT’s antenna structure to measure the offset of individual pointing covering all sky direction, which then are modeled, and the telescope’s PM is obtained. Here, we report preliminary results of SRT’s PM, where we obtain for each epoch -551.116 and -3811.549 arcsec for Azimuth encoder offset, and 1217.105 and -3343.866 arcsec for Elevation encoder offset. More accurate results can be obtained with better sky coverage observation.

Broadband excitation of spin wave using microstrip line antennas for integrated magnonic devices

Strong- and broadband-spin-wave (SW) excitation/detection structures are useful for magnonic devices. In particular, such structures are essential for observing magnonic bandgaps of magnonic crystals (MCs). Therefore, this study proposes a manufacturable broadband-SW excitation/detection antenna structure suitable for evaluating MCs. The antenna structure comprises a microstrip line fabricated on a yttrium iron garnet on a metal-covered silicon substrate. Calculations were performed using a three-dimensional finite integration technique and dispersion curves of SWs. The proposed structure exhibited high performance because of the significantly short distance between the signal line and ground plane. The generated bandwidth was ~1.69 GHz for the 8.9-μm-wavelength SW at a frequency of 4 GHz. This work proposed an appropriate antenna structure for observing magnonic bandgaps, showing high potential for the development of MCs in integrated SW devices.

Stainless-Steel Antenna on Conductive Substrate for an SHM Sensor System with High Power Demand

This paper presents the novel concept of structuring a planar coil antenna structured into the outermost stainless-steel layer of a fiber metal laminate (FML) and investigating its performance. Furthermore, the antenna is modified to sufficiently work on inhomogeneous conductive substrates such as carbon-fiber-reinforced polymers (CFRP) independent from their application-dependent layer configuration, since the influence on antenna performance was expected to be configuration-dependent. The effects of different stack-ups on antenna characteristics and strategies to cope with these influences are investigated. The purpose was to create a wireless self-sustained sensor node for an embedded structural health monitoring (SHM) system inside the monitored material itself. The requirements of such a system are investigated, and measurements on the amount of wireless power that can be harvested are conducted. Mechanical investigations are performed to identify the antenna shape that produces the least wound to the material, and electrical investigations are executed to prove the on-conductor optimization concept. Furthermore, a suitable process to fabricate such antennas is introduced. First measurements fulfilled the expectations: the measured antenna structure prototype could provide up to 11 mW to a sensor node inside the FML component.