Analysis of vertical loop antenna and its wide and flat variant performance in wearable use

Abstract This paper presents an analysis of the input impedance and radiation pattern behavior for a rectangular loop antenna when it is reshaped from a narrow square to wide and flat. The antenna operation is examined by 3D electromagnetic simulations. Parametric simulation results are shown to explain the effect of antenna dimensions on the impedance behavior. Based on the numerical results, an equivalent circuit is developed to model the impedance change due to reshaping the loop antenna. The main observations are that the decreased height and the increased width of the antenna increase the bandwidth potential of the inherently narrowband loop and increase its directivity. These characteristics together with a vertical loop orientation enable a high performance antenna for locations very close to conductive or lossy materials. Based on the presented impedance analysis, an optimized antenna prototype for a wearable use is manufactured and its performance is verified by measurements. Measured radiation efficiency for the antenna in contact with a human tissue phantom is -5.0 dB at 2 GHz and the obtainable bandwidth potential is > 10 %

Compact circularly polarized microstrip ring antenna using capacitive coupling structure for RFID readers

Abstract This paper presents a compact circularly polarized microstrip antenna for radio frequency identification (RFID) readers. The dimensions of the proposed antenna are reduced by etching a cross slot in the radiation patch and loading four grounded coupling patches on the four corners of the radiation patch. An inverted Z-shaped coupling feedline is used to realize circularly polarized operation. The measured -10 dB |S11| bandwidth, 3-dB axial ratio bandwidth and maximum gain are 872–1095 MHz, 888–933 MHz, and 5.52 dBi, respectively, at 922 MHz frequency. The overall dimension of the proposed antenna is 0.36 λ g X 0.36 λ g X 0.05 λ g (λ g is the guide wavelength at the center frequency of 915 MHz). The proposed antenna has small size with good overall performance and is suitable for compact RFID devices

Dielectric lens antennas for 300-GHz applications

Abstract Implementation of proper wireless links at submillimetre-wave and terahertz (THz) frequencies requires high-gain antennas. This simulation-based study investigates the performance of dielectric lenses and their feed antennas at 300 GHz. Parametric studies and electromagnetic simulations are used to determine the general lens properties, and the use of waveguide and on-chip antenna feeds is considered. The results show that the studied lens and feed structures can provide good, directive radiation patterns also with beam scanning

An investigation on frequency selective antenna interface based on optimization approach

Abstract New long range wireless standards, such as LTE-NB, for Internet-of-Things (IoT) devices have very challenging requirements for power consumption, however, relax, somewhat, linearity requirements of the receiver. Efforts to make low power, low cost and compact devices rise new challenges in the whole level of design including antenna interface which is the entry block of each transceiver chain. High system efficiency and selectivity as close as possible to antenna interface are key design criteria. This issue, demands the designer to ensure the optimality of the antenna interface. This paper presents a precise method for designing two-port impedance matching filters loaded by arbitrary frequency dependent loads. Above mentioned strict constraints favour using fewer number of elements and thus reduce potential losses. A design technique to quickly evaluate all possible topologies from a limited set of elements is presented. The idea is implemented in MATLAB and verified by a design example including lossy elements and practical terminations

A multiple-feed connected leaky slot antenna for in-antenna power combining in 0.13 μ m SiGe BiCMOS technology

Abstract In this paper, a differentially-driven wideband multiple-feed on-chip antenna design in 0.13 μm SiGe technology is proposed for millimeter-wave power combining applications. The in-antenna power combining concept is achieved by combining parallel amplifiers in the multi-port radiator where each port corresponds directly to a differential power amplifier (PA) stage. Specifically, the radiator is composed of a leaky slot with multiple set of differential microstrip feed lines. A wideband Marchand balun with 1.5 dB insertion loss is applied to convert the differential output to the single-ended input of microstrip feed line. In addition, the proposed differential PA has a combined output power of 10 dBm and its output is directly connected with the balun. As a result, the proposed multiple-feed antenna has four differential microstrip feed lines connected with four Marchand baluns which are driven by four parallel differential PAs respectively. Also, to compensate for the loss along the signal route such as power splitters and baluns, pre-amplification PA stage is a necessity at the input of each PA stage. In order to suppress the surface waves in the high permittivity substrate, an extended hemispherical silicon lens is integrated with the chip. Simulation results show that the antenna can cover more than 50 % fractional bandwidth at 250 GHz and calculated EIRP is 19.3 dBm

Effect of small wearable device antenna location on its impedance, bandwidth potential and radiation efficiency

Abstract In this paper, a simulation study of the effect of antenna locations on antenna matching, bandwidth potential and radiation efficiency performance operating in 3GPP Long Term Evolution (LTE) Band 3 (1710–1880 MHz), Band 20 UL (832–862 MHz) and 2.4 GHz WLAN band (2.4–2.5 GHz), in free space and with phantom, is presented. An inverted F antenna (IFA) is utilized in this study and mounted on a small cellular wrist device. The results indicate that for each band, with efficient excitation of its fundamental mode, an antenna whose electrical field maxima located at short edge of the chassis always has higher bandwidth potential and its radiation efficiency will have less reduction when introducing phantom. Moreover, changes in matching characteristic of different antenna positions vary from each band, indicating the optimal antenna placement to obtain robust matching feature. Therefore, by comparing the variations on antenna behaviors, it provides useful insights into how to select the optimal antenna locations on the device with reduced a user effect for a specific operation band

An integrated power amplifier front-end module with on-chip antenna at 180–240 GHz

Abstract This work presents a practical power amplifier front-end module solution with on-chip antennas at 180–240 GHz. It includes three parts: the frequency multiplier followed by amplifier stages and on-chip antenna array. The input signal varies from 45 GHz to 60 GHz which can be fed through the bond-wire and transmission line on the PCB. All the circuits are implemented by 130-nm SiGe BiCMOS technology

Low permittivity environmentally friendly lenses for Ku band

Abstract Lenses can be used to focus and disperse the electric field emitted by the antenna. Sustainable and environmentally friendly lenses were made from lithium molybdenum oxide (LMO) glass composite. Half spherical lenses with a diameter of a 30 mm were fabricated from LMO composite, and the antenna properties were measured with a waveguide feed. The lens enhanced radiation pattern was measured at Ku band, and the improvement in the gain was found to be 2 dB

A differential dual-band dual-polarized antenna for 5G mmWave communication system

Abstract This paper presents a differentially fed, dual-band dual-polarized antenna, suitable for 5G millimeter-wave, base station antenna array. The operating frequency range covers all the millimeter wave frequencies allotted in 5G NR from 24.25 GHz up to 40 GHz. Stacking technique is utilized to achieve wide dual bands and stable radiation pattern. The antenna geometry is simple, adhering to commercial multi-layer PCB fabrication requirements. Antenna design procedure and simulated results are discussed. The operating frequency of the lower band starts from 24.25 GHz up to 29.5 GHz while the higher band covers the 37 GHz to 40 GHz. The realized gain remains stable between 5 to 6 dB at all the operating frequencies. The isolation between the ports and cross-polar discrimination remain better than 30 dB in all the operating frequency range

Study of planar wideband mm-wave bowtie antennas over PCB ground plane

Abstract This paper presents a bowtie antenna structure integrated on PCB, where on the other side of the substrate is the antenna itself, and on the other side is a conductive ground plane. Three different cases are studied with simulations and measurements in terms of −10 dB impedance matching within 24–40 GHz bandwidth, depending on studied antenna structure. These three cases are linearly polarized single-ended bowtie, linearly polarized differentially fed bowtie, and differentially fed dual-polarized bowtie antenna. All antenna structures are on the ground plane of size 10 mm x 10 mm for easier comparison. Manufactured prototype antennas are measured and simulated with a 50 Ω coaxial feed. Simulated polarization properties and 3D radiation patterns of the dual-polarized bowtie are presented at 28 GHz and 34 GHz, which both shows 95% simulated total efficiency. Over the studied frequency range, the simulated total efficiency is better than 50%