This letter proposes a novel single-layer fourth-order balanced bandpass filter based on two coupled dual-mode loop resonators. Two pairs of balanced input/output (IO) feeding lines with unequal arms are employed to excite the outside dual-mode loop resonator, and the inside dual-mode loop resonator with meander lines is coupled to the outside one. Under differential-mode (DM) operation, three finite transmission zeros (FTZs) can be produced and controlled. Under common mode (CM) operation, the rejection level can be controlled by the length of IO feeding arms. For the demonstration, a balanced dual-mode loop filter with the center frequency of 5.2 GHz is designed, fabricated, and measured. The proposed balanced filter has the advantages of compact size, high selectivity, wide stopband of DM response, and good CM suppression.
In the study, an ultra-wideband array antenna for multifunction phased array radars (MPAR) is proposed. Due to the low-profile and ultra-wideband characteristics, the planar dipole elements are utilized to form an array antenna. Their performances are enhanced by using an optimized microstrip-sector feeding structure. The array antenna is a combination of subarrays, each of which corresponds to 4 × 4 transmit/receive channels. Four subarrays are fabricated in a standard printed circuit board (PCB) process to investigate the planar dipole array antenna theoretically and experimentally. Both simulated and measured results show that the proposed array antenna achieves 87.0% impedance bandwidth (VSWR < 2.0 in the normal direction) from 1.3 GHz to 3.3 GHz, according to the specific requirements of an MPAR project. The active VSWR is less than 2.0 and 3.0 while the scan angle is -30˚~30˚ and -45˚~45˚, respectively. It means that this array antenna has wide-scan capability. In general, the balanced optimization between the electrical and mechanical performances makes the proposed array antenna attractive for MPARs and other compact systems.
A compact frequency-tuned bandpass filter (BPF) with sharp rejection characteristic is presented. It is composed of a trans-directional (TRD) coupled line and two short-circuited stubs. By changing the capacitor values of the coupled line and the electrical lengths of the short-circuited stubs, a frequency-tuned BPF with sharp rejection is obtained. For verification, a prototype tuned from 1.0 GHz to 1.6 GHz (46.2%) is designed and fabricated. The measured results show that the proposed structure exhibits the return loss of more than 17 dB, the insertion loss of 1.4 dB, and the 3-dB fractional bandwidth (BW) of 43.2-50%. Sharp rejections are also obtained, agreeing well with the simulation results.
This letter proposes a novel balanced triple-mode microstrip bandpass filter based on a double-sided parallel-strip line resonator for the first time. The triple-mode resonator is realized by a stub-loaded structure. Stripline-like structure is employed to excite the triple-mode resonator under differential mode operation. Meanwhile, good common mode suppression can also be achieved. For the demonstration, a balanced triple-mode microstrip filter was designed, fabricated and measured.
A triple-band patch antenna operating at 0.9, 1.8 and 2.4 GHz is presented. The triple-band characteristic is realized by using a radiating patch and two meander lines achieved by embedding slots in its radiating patch. According to the current distribution of the radiating patch, the locations of two meander lines are chosen. The proposed antenna has the advantages of the easy control of each resonant frequency and relatively simple antenna structure. The measured -10 dB impedance bandwidths are 30, 40, and 30 MHz at 0.9, 1.8, and 2.4 GHz, respectively. The simulated and measured radiation patterns and gains are also presented and discussed.
This paper presents the design of a compact size, passive, W to K band subharmonic mixer with post-wall waveguide (substrate integrated waveguide) RF input interface. The mixer is based on a silica-glass structure where the post-wall waveguide and microstrip line are on separate substrates. This configuration maximizes the performance as the substrate thicknesses can be separately optimized for the lowest loss and mono-mode operation. Integration of different types of guiding structures also allows realization of e.g. millimetre-wave waveguide filters and microstrip circuits in a single structure, while preserving low-cost, low-weight and compact size. Furthermore, post-wall waveguides can be easily interfaced with conventional rectangular waveguides, as demonstrated in the paper, which simplifies millimeter-wave circuit packaging and eventual system integration. Design methodology of the mixer and transition circuits as well as measurements are presented. Minimum conversion loss of 19.6 dB was achieved at 86 GHz with 13.7 dBm/32.4 GHz LO signal. The presented design would be suitable for the future W-band cellular, radar or satellite communication systems.
Millimeter wave (mm-Wave) is today's breakthrough frontier for emerging wireless mobile cellular networks, wireless local area networks, personal area networks, and vehicular communications. In the near future, mm-Wave products, systems, theories, and devices will come together to deliver mobile data rates thousands of times faster than today's existing cellular and Wi Fi networks for an example from the era of 3G, 4G towards 5G mobile communication in near future. This paper presents studies on rain attenuation at 6 GHz and 28 GHz, which is widely used for local multipoint distribution service deployment by using the measured and prediction methods for terrestrial microwave links point to point in tropical regions. Besides this, discussion and comparison of five different reduction factor models have been presented. Several models have been proposed by researchers to account for the horizontal variation of rain fall. Five rain attenuation prediction models at tropical region are analyzed. The models are ITU-R model, revised Moupfouma model, revised Silva Mello model, Abdul Rahman model, and Lin model which have been analyzed. The objective of these studies to identify rain attenuation using prediction model for 5G network in tropical region for country like Malaysia. This study been carried out with setting of an experimental test bed. A link of path length 0.2 km was set up in Johor Bahru, Malaysia. Both the transmitter and receiver operate at frequencies of 6 GHz and 28 GHz. A tipping bucket rain rate used, and all the data have been recorded using data logger. At the end of the analysis, it is found that all the five models predict rain attenuation at less than 1 dB and 11 dB for operating microwave frequency at 6 GHz and 28 GHz for 5G Network, This findings will be useful for future 5G network designers to consider the effect of rain impairments especially in tropical region.
This letter presents novel composite dual-transmission lines. The proposed line consists of one direct series line and two identical transmission lines connected by a series lumped capacitor. The line is analyzed with an even-odd mode analysis method to have simple closed-form design equations. From the design equations, it is also observed that one can maintain a more realizable value of the impedance of the lines and achieve a good amount of miniaturization by adjusting only the lumped capacitor. To verify this technique, a 74.6% miniaturized Gysel power divider (GPD) is designed at 0.95 GHz compared to reference GPD. The physical size of the proposed GPD is 60 mm × 32 mm (equivalently 0.25λg × 0.13λg, λg is guided wavelength line). Moreover, two transmission zeros (TZs) are obtained near passband which improved the out-of-band performance.
In this paper we investigate a new design of high sensitivity photonic crystal temperature sensor (PCTS). A square lattice of silicon (Si) rods immersed in air matrix is used as a basic structure. The designed sensor consists of two inline quasi-waveguides which are coupled to a resonant cavity (RC). The sensing principle is based on Si refractive index change caused by the variation of the temperatures over a range from 0 to 80˚C. This variation leads to an important shift in the resonance wavelength. The performance of the suggested temperature sensor has been analyzed and studied using finite-difference time domain (FDTD) method. The results show that our designed structure offers a high sensibility of 93, 61 pm/˚C and quality factor of 2506.5. Its structure is very compact with total size 115.422 µm2, which is suitable for nanotechnology based sensing applications.
Ultra-reliable and low-power wireless communications are desirable for wireless networking in extreme environments such as underground tunnels, underwater, and soil. Existing wireless technologies using electromagnetic (EM) waves suffer from unpredictable multipath fading and blockage. The recent development of magnetic induction (MI) communication provides a low-power and reliable solution, which demonstrates negligible multipath fading, high penetration efficiency, and low attenuation loss in lossy media. However, existing works neglect the fact that MI communication only demonstrates such advantages in the near-field, beyond which the MI communication converges to electromagnetic wave-based communication and all the aforementioned advantages disappear. This letter develops a magnetic field propagation model to show MI communication's different performances in the near-field and the far-field. We develop rigorous models to capture the multipath fading, the penetration efficiency through inhomogeneous media, and the attenuation loss in lossy media. The results show that although MI communication can provide reasonable signals in the far-field, it only demonstrates negligible multipath fading, high penetration efficiency, and low attenuation loss in the near-field.
A stub-loaded stepped-impedance resonator (SLSIR) is proposed. Its input impedance is derived, and its resonant conditions are found. First order and second order triband bandstop filters (BSFs) are designed using this resonator. Simulations on both filters show that they generate three attenuation poles at 0.5, 1.2, and 2.1 GHz. The second order filter is also fabricated and characterized using a microwave vector network analyzer. Simulation and measurement results on the second order filter show good correlation.
This paper presents a numerical study on the application of radar and communication (RadCom) sensor nodes operating in the frequency band from 57-64 GHz. The sensor nodes are embedded in the laminate of wind turbine blades, enable a quality inspection directly after rotor blade manufacturing as well as a structural health monitoring (SHM) throughout the service life of the blade. Given by a lack of dielectric properties for typical rotor blade materials, we have performed experimental studies on material characterization including glass fibre composites, balsa wood, infusion glue, etc. This material database serves as input for wave propagation simulations in a full scale 3D rotor blade model. The analysis also includes a parametric study on path losses as well as an optimal sensor placement strategy.
Frequency diverse array (FDA) has gained remarkable attention in both radar and communication applications over the years due to its unique range-dependent beamforming. On the other hand, extremely less attention is paid to the exploitation of FDA in electronic countermeasures (ECM). Hence, this paper proposes a symmetric frequency diverse array via Chebyshev window function in ECM applications. Specifically, we utilize Chebyshev window function to design the coefficient of both transmit weights and frequency diverse increments to uncouple range-angle response of the true target to counteract deceptive ECM signals. In addition, we consider real constraint scenario, i.e., the propagation of the electromagnetic signal arriving at the true target position, which has been usually neglected in the FDA literature. The attribute of the proposed scheme is that it is able to discriminate between true target location and false target(s) location. This implies that the generated false target(s) by the jammer can be significantly suppressed in either angular or range profiles mismatch. Further, we adopt Swerling 1 model to devise generalized Neyman-Pearson design rule to evaluate the probability of detection of the proposed scheme. Numerical results illustrate the achievements of the proposed scheme.
In this paper, a compact negative-group-delay (NGD) microstrip bandpass filter is proposed. The NGD characteristic is achieved by coupling a resistor-loaded microstrip line to a square open-loop resonator. To improve the selectivity, the square open-loop resonator is loaded with an open-circuited stub for realizing two transmission zeros (TZs) in the upper stopband. To verify the proposed method, an NGD microstrip bandpass filter with a size of 0.58λg × 0.35λg is designed and fabricated. From the measured results, the NGD time of -1.08 ns at the center frequency of 1.995 GHz is obtained with the NGD bandwidth of 34 MHz (1.977-2.011 GHz), in which the insertion loss is less than 7.5 dB, and the return loss is greater than 20 dB. Furthermore, three TZs at 1.520, 2.495, and 2.735 GHz are achieved with good stopband attenuation.
In this paper, we focus on the beamforming design in a two way amplify-and-forward relay network with energy harvesting, in which a three-node system consisting of two transmitters and one relay is considered. Specifically, we investigate the joint beamforming and power splitting scheme to obtain the maximum weighted sum rate. The formulated problem is non-convex and challenging. We equivalently transform it into a more tractable problem via successive convex approximation and constrained concave-convex procedure. Then, an iterative algorithm is proposed. Numerical results demonstrate the superiority of the proposed method, as well as the eect of dynamic power splitting in improving the sum rate of relay network.
In this article, a high gain dual band rectenna is proposed for energy harvesting applications. A dual band antenna is designed and optimized to operate at 3.5 GHz and 5.8 GHz frequency bands. The antenna is based on a multilayer substrate structure excited by aperture-coupling feed. In order to achieve a maximum gain of the antenna in both bands, a rectangular cell optimized by genetic algorithms is etched on the radiating element (patch). This antenna was simulated and fabricated, and the results show a good agreement in both bands (3.5 and 5.8 GHz) with a high gain of 10.2 dBi and 8.92 dBi for the first and second bands, respectively. A dual-band rectifier is also designed and studied to harvest the radio frequency energy absorbed by the antenna to DC energy at these frequency bands (3.5 GHz and 5.8 GHz). This rectifier shows a good performance in terms of conversion efficiency which achieves 44% in the first band and 29% in the second band. As a result, an output voltage of 656.88 mV for a low input power of 0 dBm is observed when the rectifier operates at both bands.
A novel dual band-notched CPW-fed UWB MIMO antenna with mutual coupling reduction characteristics is presented in this paper. The proposed antenna uses CPW feeding to expand the antenna bandwidth. The measured impedance bandwidth with S11 < -10 dB is 137% from 3 GHz to 16 GHz. The overall size of the antenna is 46 mm × 32 mm × 1.6 mm. In order to achieve the dual band-notched characteristics, a cup-shaped branch is added to the grounding plate, and a step impedance resonator (SIR) is added to the microstrip line.By adding periodic strip branches on the back of the antenna, the mutual coupling between the two antennas is significantly reduced, which meets the requirements of practical applications. In addition, the proposed antenna has a compact size and can provide a stable radiation pattern, which is suitable for UWB communication systems.
In this paper, a contactless microwave transition is described and characterized. In our ``ElectroMagnetic Drive'' (EMDrive) measuring setup, it will be dedicated to transmit high Radio Frequency (RF) powers without any mechanical effort. It exhibits very good matching and transmission performances. It is found to transmit 100 W microwave power range at 2.45 GHz without any visible mechanical effect on a 10 mg precision balance, contrary to a previous coaxial cable. This device appears useful to every EMDrive setup and can be easily implemented.
An eight-element multiple-input-multiple-output antenna system which consists of H-shaped slot antennas is presented around the handset frame for 5G applications. Each antenna element consists of a H-shaped radiating surface and an L-shaped microstrip feeder. In the frequency bands of 3.4-3.6 GHz and 4.7-5.1 GHz, the isolation is lower than -15 dB by introducing the ladder-shaped defect ground structure. The antenna efficiency is 50%-81%, and the envelope correlation coefficient is lower than 0.02 among antenna elements. The measurement results agree well with the simulation ones, indicating that the proposed antenna can satisfy the requirements of 5G communication.
A novel compact microstrip lowpass filter with ultra-wide stopband characteristic using square ring loaded resonators is proposed. A microstrip high impedance main transmission line loaded with five square ring loaded resonators is adopted in the design of the filter. Owing to the adoption of the square ring structure, the filter achieves compact size and ultra-wide stopband. A demonstration filter with 3 dB cutoff frequency at 0.72 GHz has been designed, fabricated and measured. Results indicate that the proposed filter is able to suppress the 19th harmonic response referred to a suppression degree of 15 dB, together with a small size of 0.054λg×0.070λg, where λg is the guided wavelength at 0.72 GHz.