Band 74, Heft 11-12

This paper presents a concurrent dual-band radar system for noncontact tracking of vital signs (e.g., respiration and heartbeat), and indoor short-range localization. The proposed sensor, which has been achieved with our own customized concurrent dual-band subsystems, operates at 1.67 and 2.06 GHz synchronously. Based on the Doppler principle, tiny vital signs are obtained by analysis of spectrum of the signals received at each individual frequency band. Moreover, the location of a target is estimated based on the phase difference between these two closely spaced frequencies. The azimuth information is obtained by beam scanning. Combining the results of range and azimuth information allows the radar system to plot two-dimensional maps. As a result, the proposed radar is capable of monitoring human’s life activities and tracking the location of individuals continuously. System-level experiments were carried out to reveal the versatile capability of the life activity monitoring system.

In this paper, the scanning rate (SR) is enhanced for substrate integrated waveguide (SIW) based periodic leaky wave antenna (LWA) with continuous beam scanning. Delay line is inserted in the SIW based periodic LWA to modify the group delay profile which in turn increase the SR of the SIW based periodic LWA. Addition of the delay line enhances the SR of the SIW LWA to approximately three times from 15.6° to 47° per GHz. The prototype of the proposed LWA is fabricated and experimentally measured. The simulated and measured results show that the proposed LWA scans the angular range from −30° to +27° within a frequency span of only 1.2 GHz from 14.8 to 16 GHz (relative bandwidth of 7.7 %).

Smartdielectric resonator antenna (DRA) having beam control mechanism is anew area to be explored by antenna researchers. Proposed new geometry DRA has low loss, design flexibility, high efficiency, compact size and desired radiated beam control. Developing beam control in new geometry DRAs is investigated for the first time in this letter. Unique technique for beam control and beam width control is proposed using pit top and mount top DRA. Gain is controlled from 5.0 to 9.98 dBi and beam is controlled from ±30° to ±70° in broadside radiation pattern. U shape pit DRA has maximum directive gain of 9.98 dBi and efficiency 98% at 5.8 GHz frequency. Measured and simulated results of radiation pattern and reflection coefficient are found to be in close proximity. Hardware of U shape pit top DRA, mount top DRA, left side arc top DRA, right side arc shape top DRA is developed and investigated. Mobile and cellular communication network need wide coverage, hence large beam width is required. Narrowing of beam width at higher order mode is also achieved.

In this paper, a novel approach to achieve multiband antenna operation using metamaterial based resonant structures is presented. Multiband antenna operation is achieved by employment of complementary split ring resonators (CSRR) printed in the ground plane. The CSRRs resonate at different frequencies according to their optimized dimensions. Proposed approach features simple design and fabrication possibility compared to other methods of achieving multiband antenna operation such as usage of composite right/left-handed (CRLH) transmission line or split ring resonators (SRR) or CSRR around the patch surface. The proposed method is demonstrated through simulation and experimental measurements using three CSRRs with different resonant frequencies together with a tuning CSRR and a radiating patch. Contribution of different CSRRs to obtain multiple resonances have been shown by surface current plots. Measured antenna gain of 2.78, 1.27 and 3.45 dB has been obtained at frequencies of 5.25, 6.28 and 7.29 GHz respectively. The measurements done on developed antenna exhibits close agreement with the simulation results. In context with the current communication application trends involving multiple operating bands like 5G, this approach may have immense application potential since the same can be adopted to achieve compact multiband antennae operation in other frequency bands of interest.

In the present article authors propose the design and analysis of an octagonal shape multiband metamaterial loaded antenna with implementation of hybrid fractal geometry for wireless applications. Multiband features in the antenna structure is realized by applying the slotted and hybrid fractalization of Moore and Koch curve approach in radiating section along with introduction of two metamaterial SRR cells. The frequency band reconfigurability characteristics in proposed design is achieved by placing the PIN diode inside the connecting strip between the central hybrid fractal geometry and feedline. During forward bias condition of PIN diode antenna structure resonates at hepta (seven) band mode at WiMAX (3.5 GHz)/Lower C-band (4.41 GHz)/WLAN (5.4/5.8 GHz)/Lower X-band (8.26 GHz)/Upper X-band (10.48 GHz)/Lower Ku-band (13.35 GHz)/Middle Ku-band (14.42 GHz) wireless standards with S 11  ≤ −10 dB. Proposed antenna represent the hexa and hepta band features during reverse bias (OFF-state) and forward bias condition (ON-state) of PIN diode respectively. A stable and consistent radiation patterns, appropriate impedance matching and an acceptable gain are achieved at all the operating frequencies of the proposed antenna.

In this paper the design and analysis of two dimensional photonic crystals based all optical AND logic gate is investigated. A logic gate implements a Boolean function and thus performs a logical operation on one or several logic inputs in order to produce a single logic input. The proposed all optical AND gate is designed with line and point defect using a hexagonal lattice with “Y” shaped defect. In order to meet the requirements for high speed networks the proposed gate designed. The functional parameters such as contrast ratio, bit rate, normalized efficiency and response time are calculated. The performance of the AND gate is analyzed by using the Finite Difference Time Domain method. The proposed logic gate is designed to operate at 1550 nm. It provides high contrast ratio and minimum delay time. Hence it is suitable for optical sensors and optical integrated circuits.

In this paper, a balanced-to-balanced (BTB) branch-slotline directional coupler (DC) is firstly presented, which can realize an arbitrary power division ratios (PDRs). The coupler is composed by microstrip-to-slotline (MS) transition structures and branch-slotline coupled structures. The single-ended to balanced-ended conversion is simplified and easy to implemented by the MS transition structures, which intrinsically leads to the differential-mode (DM) transmission and common-mode (CM) suppression. Moreover, the different PDRs which are controlled by the widths of branch-slotlines can be achieved. In order to verify the feasibility of the proposed design method, two prototype circuits of the proposed coupler with different PDRs are fabricated and measured. The return loss and the isolation of two designs are all better than 10 dB. Moreover, the CM suppressions are greater than 35 dB. A good agreement between the simulation and measurement results is observed.

In this paper, a novel technique based on transmission-only measurements is proposed to determine complex permittivity and permeability of low-loss materials. The proposed method removes the influences of the sample thickness and avoids the resonances in the extracted parameters. Both the experiment and simulation are applied to present the advantages of the proposed method. Compared with the well-known Nicolson–Ross–Weir (NRW) method, the proposed method shows a good performance in resonance avoidance. Compared with the conventional method based on the transmission-only measurements, the proposed method shows a good performance in accuracy.