No Arabic abstract
Microstrip patch antennas (MPAs) are rapidly gaining more attention due to the proliferation of communication devices and systems with frequencies becoming more suitable for the size and performance of this type of antenna. Due to recent advancements in semiconductor technology, high dielectric constant materials are used to achieve additional size reduction which has made MPAs very useful and popular in the design of mobile devices and wireless systems. However, MPAs suffer from problems associated with narrow bandwidth and low gain. Techniques employed for improving the performance of MPA hinge on tweaking features such as the patch size, substrate height, ground plane size and feeding method. In view of this, this research designs and analyzes the performance of an X-band MPA for wireless systems using CST Microwave Studio. Including the ground plane, the proposed design has a low profile structure of 17 mm x 17 mm x 1.6 mm which is suitable for wireless systems. The proposed design also resonates at a frequency of 10 GHz with an omnidirectional radiation pattern exhibiting a gain of 7.2 dBi. Return Loss, VSWR, Gain and Radiation Pattern are the performance indicators employed in this research. The proposed MPA design demonstrates marked performance improvement when benchmarked with a similar MPA designed for 5G applications.
Ultra-wideband is increasingly advancing as a high data rate wireless technology after the Federal Communication Commission announced the bandwidth of 7.5 GHz (from 3.1 GHz to 10.6 GHz) for ultra-wideband applications. Furthermore, designing a UWB antenna faces more difficulties than designing a narrow band antenna. A suitable UWB antenna should be able to work over the Federal Communication Commission of ultra-wide bandwidth allocation. Furthermore, good radiation properties across the entire frequency spectrum are needed. This paper outlines an optimization of fractal square microstrip patch antenna with the partial ground using a genetic algorithm at 3.5 GHz and 6 GHz. The optimized antenna design shows improved results compared to the non-optimized design. This design is optimized using a genetic algorithm and simulated using CST simulation software. The size of the optimized design is reduced by cutting the edges and the center of the patch. The optimized results reported, and concentrated on the rerun loss, VSWR and gain. The results indicate a significant enhancement as is illustrated in Table II. Thus, the optimized design is suitable for S-band and C-band applications.
A novel and compact dual band dual sense circularly polarized microstrip patch antenna with single coaxial feed has been reported in the present work. The key idea of generating dual band circular polarisation (CP) is the integration of a square patch with corner truncation and a smaller concentric circular patch with double slits. The first resonance is provided by the larger patch whose corner truncation generates two orthogonal modes. The inner patch controls the higher-order resonance with the CP contributed by two narrow slits. The higher order resonating frequency can be monitored by controlling the dimensions of the circle and the slits. The antenna provides the CP in two orthogonal planes with two different sense of polarisation. The lower order CP is of left-handed orientation, whereas the higher order shows right-handed polarization. The cross-polarization level is also found to be very low.
This paper investigates the impact of the channel state information (CSI) and antenna correlation at the multi-antenna relay on the performance of wireless powered dual-hop amplify-and-forward relaying systems. Depending on the available CSI at the relay, two different scenarios are considered, namely, instantaneous CSI and statistical CSI where the relay has access only to the antenna correlation matrix. Adopting the power-splitting architecture, we present a detailed performance study for both cases. Closed-form analytical expressions are derived for the outage probability and ergodic capacity. In addition, simple high signal-to-noise ratio (SNR) outage approximations are obtained. Our results show that, antenna correlation itself does not affect the achievable diversity order, the availability of CSI at the relay determines the achievable diversity order. Full diversity order can be achieved with instantaneous CSI, while only a diversity order of one can be achieved with statistical CSI. In addition, the transmit antenna correlation and receive antenna correlation exhibit different impact on the ergodic capacity. Moreover, the impact of antenna correlation on the ergodic capacity also depends heavily on the available CSI and operating SNR.
Wireless capsule endoscopy (WCE) systems are used to capture images of the human digestive tract for medical applications. The antenna is one of the most important components in a WCE system. In this paper, we provide novel small antenna solutions for a WCE system operating at the 433 MHz ISM band. The in-body capsule transmitter uses an ultrawideband outer-wall conformal loop antenna, whereas the on-body receiver uses a printed monopole antenna with a partial ground plane. A colon-equivalent tissue phantom and CST Gustav voxel human body model were used for the numerical studies of the capsule antenna. The simulation results in the colon-tissue phantom were validated through in-vitro measurements using a liquid phantom. According to the phantom simulations, the capsule antenna has -10 dB impedance matching from 309 to 1104 MHz. The ultrawideband characteristic enables the capsule antenna to tolerate the detuning effects due to electronic modules in the capsule and due to the proximity of various different tissues in gastrointestinal tracts. The on-body antenna was numerically evaluated on the colon-tissue phantom and the CST Gustav voxel human body model, followed by in-vitro and ex-vivo measurements for validation. The on-body antenna exceeds -10 dB impedance matching from 390 MHz to 500 MHz both in simulations and measurements. Finally, this paper reports numerical and experimental studies of the path loss for the radio link between an in-body capsule transmitter and an on-body receiver using our antenna solutions. The path loss both in simulations and measurements is less than 50 dB for any capsule orientation and location.
In this paper, we consider a three-node cooperative wireless powered communication system consisting of a multi-antenna hybrid access point (H-AP) and a single-antenna relay and a single-antenna user. The energy constrained relay and user first harvest energy in the downlink and then the relay assists the user using the harvested power for information transmission in the uplink. The optimal energy beamforming vector and the time split between harvest and cooperation are investigated. To reduce the computational complexity, suboptimal designs are also studied, where closed-form expressions are derived for the energy beamforming vector and the time split. For comparison purposes, we also present a detailed performance analysis in terms of the achievable outage probability and the average throughput of an intuitive energy beamforming scheme, where the H-AP directs all the energy towards the user. The findings of the paper suggest that implementing multiple antennas at the H-AP can significantly improve the system performance, and the closed-form suboptimal energy beamforming vector and time split yields near optimal performance. Also, for the intuitive beamforming scheme, a diversity order of (N+1)/2 can be achieved, where N is the number of antennas at the H-AP.