Low-profile and closely spaced four-element mimo antenna for wireless body area networks

A compact four-element multiple-input multiple output (MIMO) antenna is proposed for medical applications operating at a 2.4 GHz ISM band. The proposed MIMO design occupies an overall volume of 26 mm × 26 mm × 0.8 mm. This antenna exhibits a good impedance matching at the operating frequency of the ISM band, whose performance attributes include: isolation around 25 dB, envelope correlation coefficient (ECC) less than 0.02, average channel capacity loss (CCL) less than 0.3 bits/s/Hz and diversity gain (DG) of around 10 dB. The average peak realized gain of the four-element MIMO antenna is 2.4 dBi with more than 77 % radiation efficiency at the frequency of interest (ISM 2.4 GHz). The compact volume and adequate bandwidth, as well as the good achieved gain, make this antenna a strong candidate for bio-medical wearable applications

Design of mobile band subsurface antenna for drainage infrastructure monitoring

This paper presents an underground subsurface wireless sensor for drainage infrastructure water level monitoring. It operates from 800 to 2170 MHz to cover the required GSM850/900, GSM1800/1900 and UMTS bands. The system consists of a wideband antenna, transceiver, data acquisition unit and an ultrasonic sensor. The proposed antenna is a 3-dimensional inverted double F antenna and has an envelope size of 90 × 63.5 × 32 mm^3 , which is acceptably small for a cramped subsurface passageway environment. The antenna design was developed using software simulation to optimise its key parameters of return loss and radiation pattern, these being evaluated both in free space and in the partially underground environment. The design developed was then realised in hardware and tested in a representative subsurface location: a utility manhole chamber. It was found that the location of the antenna in the chamber had a significant effect on its performance, but a location that was acceptable for operational purposes was found by experiment. The overall system, including a transceiver, was demonstrated to operate satisfactorily for utility monitoring purposes, including acceptable levels of path loss for communication with mobile communication base stations

A Compact Semi-Circular and Arc-Shaped Slot Antenna for Heterogeneous RF Front-Ends

In this paper, a new miniaturized compact dual-band microstrip slot antenna is presented. To achieve the dual-band characteristics, two adjunct partial arc-shaped small slots are joined to two main circular slots embedded in the ground of the antenna structure. With a reduced size of 30 × 28.5 × 0.8 mm3, the proposed antenna presents a dual-band characteristic. The design is optimized using a High Frequency Structure Simulator (HFSS) followed by experimental verifications. An impedance bandwidth, for S11 ≤ 10 dB, that covers the 1.8 GHz and 2.4 GHz bands is accomplished, which makes the proposed antenna basically suitable for hand-held devices and medical applications. More applications such as digital communication system (DCS) 1.71–1.88 GHz, personal communication services (PCS) 1.85–1.99 GHz, Universal and mobile telecommunications system UMTS 1.92–2.17 GHz, Bluetooth 2.4–2.5 GHz, and Wi-Fi 2.4–2.454 GHz, Industrial Scientific and Medical radio frequency (RF) band ISM-2.4 GHz, Wireless Local Area Network (WLAN-2.4) are possible by simply changing one of the geometrical antenna dimensions. The antenna is characterized by stable radiation patterns as well

Reconfigurable Microstrip Printed Patch Antenna for Future Cognitive Radio Applications

A family of compact microstrip antennas are presented targeting applications such as Long-Term Evolution (LTE), Wireless Local Area Networks (WLAN), Universal Mobile Telecommunications system (UMTS), Global System Mobile (GSM) and global positioning system (GPS). These antennas consist of a rectangular shaped structure printed over FR4 substrate. The antenna occupies a small volume of 70x54x1.6mm3. A 50-Ohm strip line was used to feed the proposed antennas. For miniaturization purposes, an I- shaped slot was inserted in the appropriate location on the radiator resulting in the second version (antenna with I-shaped slot). The integration of the slot helped towards shifting the resonant frequency downwards, which potentially created an additional resonant frequency to cover the WLAN2400MHz, but this resonant frequency is still static in nature. Thus, tuning mechanisms were introduced to tune the resonant frequency over a wide continuous frequency range. A lumped capacitor was firstly used as the tuning approach, in which its capacitance was varied from 0.5pF to 3pF, covering the frequency range from 2300MHz to 1500MHz. Secondly, the varactor diode was exploited to verify this; by changing the bias voltage across the varactor from 0.21V to 12.9V, the antenna operates over the targeted range from 1500MHz to 2300MHz. Both the simulated and measured results show a stable performance. The proposed antenna may be suitable for future cognitive radio system

Design of multi‐standard single/tri/quint‐wideband asymmetric stepped‐impedance resonator filters with adjustable TZs

This study presents an original asymmetric stepped-impedance resonator filter combined with meander coupled-line structures and enabling the realisation of finite transmission zeros (TZs) and the implementation of multi-band bandpass filters. The meander coupled sections (MCSs) tune the TZs and resonant frequencies: with higher-order spurious frequencies cancelled by the TZs, a single wideband with wide stopband from 1.18 to 1.84 GHz is possible. Furthermore, by positioning the finite TZs between the high-order spurious frequencies and adjusting the coupling strength between resonators, a quint-wideband filter can be realised, with centre frequencies of 1.19, 4.29, 5.43, 6.97, 9.9 GHz and fractional bandwidths of 31.9, 15.4, 15.8, 4.3, 39.2%, respectively. More importantly, two filters with single/quad-wideband performance can be realised by tuning the parameters of the MCS, and therefore they can be designed separately by using only one original structure. The triple-wideband filter is realised with the help of the asymmetric parallel uncoupled microstrip section. These filter structures enjoy the advantage of single/multi-band versatility, structure reusability and simplicity. The good in-band and out-of-band performance, low loss and simple structure of the proposed single/tri/quint-wideband filters make them very promising for applications in future multi-standard wireless communication