In this paper, a horizontally meandered strip (HMS) feed technique is proposed to achieve good impedance matching and symmetrical broadside radiation patterns for a single-fed broadband circularly polarized stacked patch antenna, which is suitable for universal ultrahigh frequency (UHF) RF identification (RFID) applications. The antenna is composed of two corner truncated patches and an HMS, all of which are printed on the upper side of the FR4 substrates. One end of the HMS is connected to the main patch by a probe, while the other end is connected to an SMA connector. Simulation results are compared with the measurements, and a good agreement is obtained. The measurements show that the antenna has an impedance bandwidth (VSWR <; 1.5) of about 25.8% (758-983 MHz), a 3-dB axial ratio (AR) bandwidth of about 13.5% (838-959 MHz), and a gain level of about 8.6 dBic or larger within the 3-dB AR bandwidth. Therefore, the proposed antenna can be a good candidate for universal UHF RFID readers operating at the UHF band of 840-955 MHz. In addition, a parametric study and a design guideline of the proposed antenna are presented to provide the engineers with information for designing, modifying, and optimizing such an antenna. At last, the proposed antenna is validated in RFID system applications.

A novel proximity-coupled probe-fed stacked patch antenna is proposed for Global Navigation Satellite Systems (GNSS) applications. The antenna has been designed to operate for the satellite navigation frequencies in L-band including GPS, GLONASS, Galileo, and Compass (1164-1239 MHz and 1559-1610 MHz). A key feature of our design is the proximity-coupled probe feeds to increase impedance bandwidth and the integrated 90deg broadband balun to improve polarization purity. The final antenna exhibits broad pattern coverage, high gain at the low angles (more than -5 dBi), and VSWR <1.5 for all the operating bands. The design procedures and employed tuning techniques to achieve the desired performance are presented.

A novel capacitive-coupled probe-fed circularly polarized (CP) microstrip antenna with coplanar parasitic ring slot patch has been proposed for the International Maritime Satellite (INMARSAT) and the Global Positioning System (GPS) applications. The key feature of the design is employing capacitive-coupled four-probe feeds to increase impedance bandwidth and adopting coplanar parasitic ring slot patch to enhance CP bandwidth. The feed network is compact and neat using only T-junction power dividers and phase shifters with shunted short-circuited microstrip stubs for lightning protection. The characteristics of the proposed antenna have been studied by simulation and experiment. The final antenna can produce a ${ S}_{11}<-$ 14 dB impedance bandwidth of nearly 27%, a 3-dB axial-ratio bandwidth of nearly 16%, and a gain of higher than 8 dB in the whole maritime satellite communication work band.

Mobile edge computing (MEC) can augment the computation capabilities of mobile terminals (MTs) through offloading the computational tasks from the MTs to the MEC-enabled base station (MEC-BS) covering them. However, the load of MEC-BS will rise as the increase of the scale of tasks. Existing schemes try to alleviate the load of MEC-BS through refusing, postponing, or queuing the offloading requests of the MTs; thus, the users' QoS will largely deteriorate due to service interruption and prolonged waiting and execution time. In this paper, we investigate the cooperations of multiple MEC-BSs and propose a novel scheme to enhance the computation offloading service of an MEC-BS through further offloading the extra tasks to other MEC-BSs connected to it. An optimization algorithm is proposed to efficiently solve the optimization problem which maximizes the total benefits of time and energy consumptions gained by all the MTs covered by the MEC-BS. A balance factor is used to flexibly adjust the bias of optimization between minimizations of time and energy consumption. Extensive simulations are carried out in eight different scenarios, and the results demonstrate that our scheme can largely enhance the system performance, and it outperforms the reference scheme in all scenarios.

An artificial neural network-based synthesis model is proposed for the design of single-feed circularly-polarized square microstrip antenna (CPSMA) with truncated corners. To obtain the training data sets, the resonant frequency and Q-factor of square microstrip antennas are calculated by empirical formulae. Then the size of the truncated corners and the operation frequency with the best axial ratio are obtained. Using the Levenberg-Marquardt (LM) algorithm, a three hidden layered network is trained to achieve an accurate synthesis model. At last, the model is validated by comparing its results with the electromagnetic simulation and measurement. It is extremely useful to antenna engineers for directly obtaining patch physical dimensions of the single-feed CPSMA with truncated corners.

A novel self-matched negative group delay (NGD) microwave circuit based on the signal interference technique is proposed to eliminate the performance degradation due to the temperature-dependent resistance variation. The proposed circuit consists of unequal power dividing/combining structures and coupled-line phase shifter, which can be directly synthesized with prescribed NGD time and insertion loss (IL). To verify the proposed method, an NGD circuit with a size of 0.41λ _g × 0.41λ _g is designed and fabricated. From the measured results, NGD time of -2.09 ns at the center frequency of 1.016 GHz is obtained with NGD bandwidth of 14.2% (0.944-1.088 GHz), in which the IL is less than 18.1 dB and the return loss is greater than 33 dB.