Unequal Slots Research Articles

Analysis of slotted matching antenna for millimeter wave applications

Millimeter wave applications gives an efficient solution to furnish peak data rates in indoor wireless access systems. Propagation of the signal will get up-shot because of few considerations in advanced communication appliances. Superior output and high directivity antennas are mandatory to overcome these consequences. By installing unequal slots in the structure, the tree-shaped unequal slotted antenna is analyzed for the variations in impedance, directivity changes and reflection coefficient. The better quality results have been observed for the proposed structure while compare with existing structures. The maximum simulation reflection coefficient(S11) of tree-shaped unequal slotted antenna is 45.12 dB, directivity is 6.54 dBi with the efficiency of 60 % and at 60 GHz, and the measurement value of 36.35 is observed which covers the complete RADAR applications which have an unlicensed bandwidth. The dimension of tree-shaped unequal slotted antenna is observed as 12*7*0.508 mm3. The proposed tree-shaped unequal slotted antenna is well suited for millimeter-wave appliances such as Microcell, Femtocell and macrocell applications because of its good bandwidth and less dimension.

Bandwidth Enhancement and Size Reduction of a Low-Profile Polarization-Reconfigurable Antenna by Utilizing Multiple Resonances

A new design method to significantly expand the axial ratio (AR) bandwidth of a single-fed, low-profile circularly polarized (CP) antenna without relying on any complex feed network or occupying a large transverse dimension is presented. First, four small patches arranged in chessboard pattern are utilized as the main radiator, and meanwhile, a cross slot with unequal slot lengths is adopted to excite triple sequentially orthogonal modes, aiming to attain two CP modes (AR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and AR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). Second, in order to further considerably enhance the AR bandwidth and concurrently reduce the overall size, the feeding cross-slot resonance is favorably excited and effectively coupled by the chessboard patches to produce a new slotline-based CP mode (AR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) located before AR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> . Finally, an I-shaped top-loaded monopole fence, as a new degree of design freedom, is employed to collaboratively regulate these multiple resonances to form a wide AR bandwidth covering AR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , AR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and AR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> . Results show that, on the premise of keeping the inherent compact-size and low-profile advantages of microstrip antenna, the 3 dB AR bandwidth is remarkably enhanced up to 30.1% by the combination of the three CP modes. Based on the design method, a wideband polarization-reconfigurable antenna with switchable linear polarization (LP), left-handed circular polarization (LHCP), and right-handed circular polarization (RHCP) states is further designed and experimentally validated. The measured results demonstrate that, with quite compact transverse size ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.16\lambda _{0}^{2}$ </tex-math></inline-formula> ) and low profile ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.04\lambda _{0}$ </tex-math></inline-formula> ), a wide overlapped bandwidth (27.6%) of the polarization-reconfigurable antenna is successfully accomplished.

Investigation on the vibration characteristics of circular saw blade with different slots

Irregular vibration of circular saw blade caused by complex forces in the process of cutting harms the operators, product quality and the life of circular saw blade. In this paper, the modal analysis of circular saw blades with different slot length and four kinds of unequal slot length saw blades are carried out based on the finite element theory. The vibration characteristics of circular saw blades with different slot length is studied. The results show that the natural frequency and the maximum deformation increase with the increasing slot length. In the case of higher order after the 5th order, the phenomenon is even more obvious. The effects of slot length, slot depth and diamond segment on natural frequency are compared. The results show that slot length has the greatest effect on natural frequency. Circular saw blades of different structures with unequal slot length can be selected to avoid resonance during operation.

Design of a single-layer broadband reflectarray using circular microstrip patch loaded with two unequal slots

A linearly polarized single-layer single-resonator reflectarray, which is designed using a simple circular patch loaded with two unequal rectangular slots, is investigated for the first time. For the proposed design, the linearity and sensitivity of the phase curve (S-curve) can be easily optimized by adjusting the ratio of the two unequal slots changeable according to a simple design equation. Here, the patch radius serves as a phase-shifting geometrical parameter and it is able to achieve a wide phase range of more than 458° with low phase sensitivity and a low reflection loss of less than 0.5 dB. With the use of the optimized phase curve, an offset-fed 13 × 13 full-fledged reflectarray with a square aperture is designed, fabricated and measured. Measurement results show that a −1-dB gain bandwidth of 11.8% and an antenna gain of 23.4 dBi are realizable at the center frequency of 9.3 GHz. Also, the proposed reflectarray has an aperture efficiency of 42% and a radiation efficiency of 98%. The proposed reflectarray has a simple structure and it is able to achieve smooth phase curve, low cross-polarized radiation field and low sidelobes.

Analysis and design of 18‐slot/10‐pole six‐phase fault‐tolerant permanent magnet synchronous motor for electric vehicles

This study analyses a double Y shaft 30° winding for six-phase fault-tolerant permanent magnet synchronous motors and introduces a novel modular 18-slot stator topology used in high-performance electric vehicles with unequal teeth width and unequal slot size. The new topology adopts double-layer winding in the same phase and single-layer winding in the adjacent phase. Additionally, two new pole/slot combinations for the six-phase motor, 18-slot/10-pole and 18-slot/14-pole, are proposed by analysing the air-gap flux harmonics that are produced by the stator winding. In addition, the optimal design of the 18-slot/10-pole motor is determined by using the average torque and the torque ripple as indexes. The motor can run continuously in the range of 0–4 times the rated speed with a one-time short-circuit current, a high isolation capability in the different phases and a high efficiency. The final parameters and performance of the 18-slot/10-pole motor are provided.

A slotted circularly polarized semicylindrical conformal patch antenna for EBS and BRS bands

A circularly polarized semicylindrical patch antenna loaded with unequal slots for use in S-band applications is presented and designed. Circular polarization operation is demonstrated for both planar and semicylindrical structures by embedding four quarter-circular slots with asymmetric radius at the four corners and two symmetric semicircular slots on both side edges. An axial ratio (AR) bandwidth of 50 MHz and a return loss band width of 210 MHz are achieved with the planar structure. The 3-dB AR beam widths obtained in the E and H plane are 85° and 65°, respectively, at a frequency of 2.5 GHz for the planar patch. The semicylindrical antenna exhibits a beam width of 66.9° in the E plane and 113° in the H plane. For the semicylindrical antenna, a 3-dB axial ratio bandwidth of around 59 MHz and a −10 dB return loss bandwidth of 214 MHz with a uniform directive gain of 7.04 dB in the pass band are also achieved.

Detent Force Minimization of a Tubular Flux-Switching Permanent Magnet Motor Using Un-Equal Width Stator Slots Based on Taguchi Method

The detent force caused by the cogging effect and end effect will seriously affect the operation of a tubular flux-switching permanent magnet motor (TFSPMM). This paper proposes a method to weaken the end effect and minimize the detent force and force ripple of a TFSPMM using un-equal width stator slots. To overcome the problem of excessive calculation, the Taguchi method is performed to find the optimal combination of stators with unequal slot width. The proposed method can significantly decrease the detent force and force ripple and keep the thrust force basically unchanged. The permanent magnet flux linkage, detent force and electromagnetic force are calculated by the two dimensional (2D) finite element method (FEM).

Microstrip dual mode multi-bandpass filters based on tree fractal slotted resonator for wireless communication

Dual mode microstrip multi-bandpass filter is proposed with tree fractal slot on a square patch resonator. The tree fractal slotted resonators are generated from conventional square patch using an iterative tree fractal generator method. A single square patch is used for realizing both dual and tri-bandpass filters exploiting the dominant, higher order and its corresponding degenerate resonant modes by the tree fractal iteration on the diagonal unequal slots on the square patch.The resonant peaks, transmission zeros and bandwidth of the pass bands can be tuned by varying the length and width of the fractal slot. By optimizing various parameters dual mode dual and tri-band pass filters are simulated, fabricated and measured. The proposed filter finds application in wireless communication devices and falls in the bands of GSM, WLAN, Bluetooth, Zigbee, WiMax and WiFi.

Microstrip dual mode multi-bandpass filters based on tree fractal slotted resonator for wireless communication

Dual mode microstrip multi-bandpass filter is proposed with tree fractal slot on a square patch resonator. The tree fractal slotted resonators are generated from conventional square patch using an iterative tree fractal generator method. A single square patch is used for realizing both dual and tri-bandpass filters exploiting the dominant, higher order and its corresponding degenerate resonant modes by the tree fractal iteration on the diagonal unequal slots on the square patch.The resonant peaks, transmission zeros and bandwidth of the pass bands can be tuned by varying the length and width of the fractal slot. By optimizing various parameters dual mode dual and tri-band pass filters are simulated, fabricated and measured. The proposed filter finds application in wireless communication devices and falls in the bands of GSM, WLAN, Bluetooth, Zigbee, WiMax and WiFi.

Power Control for Device-to-Device Communication with a Hybrid Relay Mode in Unequal Transmission Slots

Device-to-device (D2D) pairs are allowed to reuse the spectrum of cellular users who are in a good quality channel state with underlaying cellular network. However, cellular users usually suffer a poor performance in term of achievable rate when they are in a cell edge or in deep fading. To solve this problem, a hybrid relay-aided D2D communication scheme with a two-antenna infrastructure and using two unequal transmission slots is proposed in this paper. Different from the pure half-duplex and full-duplex D2D relay work, the hybrid-duplex relay mode that we propose enables the D2D relay to receive and transmit signals at the same time in the first time slot. Thus, it is similar to the full-duplex which could increase the spectrum efficiency. In addition, in the second time slot, the D2D relay will forward only the cellular user’s signals, thus avoiding the transmission of mixed signals which would deteriorate the system performance, similarly to the half-duplex mode. Moreover, by bringing in a slot splitting factor, the relay node in our hybrid-duplex mode is set to guarantee the matching of the transmission rate in two hops. We formulate the problem of maximizing the D2D transmission rate while guaranteeing in priority the minimum rate for the cellular user. By using the method of rate matching and linear programming, we deduce the expression of the slot splitting factor as well as the optimal power allocation for the base station and D2D relay, while guaranteeing the minimum rate requirement for the cellular user in a close form. The simulation results show that the proposed relay-based hybrid-duplex D2D scheme outperforms the existing half-duplex and full-duplex relay-based D2D communication schemes in term of achievable rate.

Coupling topology of substrate integrated waveguide filter using unequal length slots with non‐resonating nodes

A novel coupling topology of substrate integrated waveguide filter with unequal-length slots is proposed. This filter consists of two resonators and a pair of unequal-length slots, which can be considered as two-stage bypass coupling resonators. There exist two resonant modes (TE101 and TE102) in each resonator. TE101 mode is coupled by the long slot, and TE102 mode is coupled by the short slot, which can achieve two resonant modes couplings between adjacent cavities. This structure uses TE102 mode to design the centre frequency of the passband and regards TE101 mode as spurious response. As a result, this filter leads to three transmission zeros (TZs), two TZs locate above the passband and one TZ is below the passband. The filter is fabricated and measured, the measured results agree well with simulated ones.

Cross-Slot-Coupled Wide Dual-Band Circularly Polarized Rectangular Dielectric Resonator Antenna

A cross-slot-coupled wide dual-band circularly polarized (CP) rectangular dielectric resonator antenna (DRA) is investigated. The DRA has a large aspect ratio of 3.2:1. By using a cross-slot of unequal slot arms, three sets of degenerate orthogonal modes of TE111, TE121, and TE131 can be excited simultaneously to generate dual-band CP fields. It is found that the lower band is composed of the TE111 and TE121 modes, while the upper band is formed by the TE131 mode. The 3-dB axial-ratio (AR) bandwidths are 19.8% and 6.2% for the lower and upper bands, respectively. To verify the simulation, measurement was carried out and reasonable agreement was obtained.

A Circularly Polarized Small-Size Microstrip Antenna using a Cross Slot with Enhanced Bandwidth &amp; Gain

In the recent years the development in communication systems requires the development of low cost, minimum weight, low profile antennas that are capable of maintaining high performance over a wide spectrum of frequencies. This technological trend has focused much effort on the design of a Microstrip patch antenna. A new, circularly polarized small-size microstrip antenna using a proximity coupled feed method is proposed. A simple configuration based on a cross slot with unequal slot lengths on a circular patch is adopted to realize a small-size element antenna. The measured results verify the circular polarization, and the antenna radius was reduced by about 22% by using the slot lengths which are nearly equal to the diameter of the circular patch antenna. Good impedance and axial ratio characteristics have been obtained.

Investigations on miniaturized multifrequency microstrip patch antennas for wireless communication applications

This paper is aimed at proposing some single layer, single feed, multifrequency slotted microstrip patch antennas for wireless communication applications. Four different slotted patch antennas fabricated with FR-4 () substrate are proposed and experimentally studied. Unequal narrow rectangular slots are introduced on the respective patches to reduce the size of the antennas. Multiple resonant frequencies are also obtained by cutting unequal slots. The measured result shows that the size of the proposed antennas have been reduced by 89, 90, 92, and 67%, respectively, when compared with their respective conventional rectangular microstrip antennas with same patch areas. The proposed antenna structures also provides increased frequency ratio (the ratio of second or higher resonant frequency to the first resonant frequency). All the antenna structures are simulated using method of moment based IE3D™ software. Good agreement is achieved between simulated and measured (by vector network analyzer) results.

Compact microstrip antenna for mobile communication

A single layer, single feed compact rectangular microstrip antenna is proposed. Resonant frequency has been reduced drastically by cutting unequal rectangular slots at the edge of the patch. Two rectangular slots are introduced at the left and right side of the patch to reduce the resonant frequency. The widths of the rectangular slots are different to improve the gain bandwidth performance of the antenna. The antenna size has been reduced by 73.9% when compared to a conventional rectangular microstrip patch antenna. The characteristics of the designed structure are investigated by using Method of Moment-based electromagnetic solver, IE3D. There is a reasonable agreement between these simulated data and measured values. An extensive analysis of the return loss, radiation pattern, gain, and efficiency of the proposed antenna is shown in this paper. The simple configuration and low profile nature of the proposed antenna leads to easy fabrication and make it suitable for the applications in Wireless communication system. Mainly, it is developed to operate in the mobile communication range of 900 MHz–1.8 GHz. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:954–957, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27517

Bandwidth Broadening of Dual-Slot Antenna Using Substrate Integrated Waveguide (SIW)

This letter presents a dual-slot antenna etched on a substrate integrated waveguide. This antenna is designed, fabricated, and measured to operate at X-band. It uses two unequal slots in order to increase the bandwidth. The measured results show a bandwidth of 8.5%, which is twice that of the standard dual-slot antennas. Attractive features including low cost, compact size, and planar form make this antenna easy to integrate within microwave planar circuits.

Suppression of thrust fluctuation of doubly-fed linear motor

Because the mover and stator of a doubly-fed linear motor are both equipped with three-phase windings, the motor enables contactless energy to be transferred from the stator to the mover. Thus, when a doubly-fed linear motor is used in the linear driving system of trains, neither an overhead line nor a third rail is needed. However, the doubly-fed motor will lead to more severe thrust fluctuation than the unilateral motors. In order to overcome this shortcoming, the thrust fluctuation of the doubly-fed motor should be analyzed. In this paper, an expression for motor thrust is derived. It points out that the slot effect caused by the slotted structure is the main reason for the increase of thrust fluctuation. The method of adopting unequal pole pitch and unequal slot numbers per pole per phase of stator and mover, is proposed to weaken the slot effect when designing the motor slot parameters. Three different motor models are simulated by ANSOFT. The proposed method results in a motor thrust fluctuation coefficient of 8.4%, compared to 49.4% for the conventional method. Therefore, the motor’s thrust fluctuation is effectively suppressed by the proposed method.

Multi-resonant Slotted Microstrip Antenna for C, X and Ku-Band Applications

A compact slotted patch antenna with single layer, single feed is simulated in this paper. By cutting two unequal slots at the upper right and lower left corner from the conventional microstrip patch antenna, resonant frequency has been reduced drastically compared to a conventional microstrip patch antenna and also simulated antenna size has been reduced by 34.22% with an increased frequency ratio.

Enhancement of ultra-wideband microstrip monopole antenna by using unequal arms V-shaped slot printed on metamaterial surface

A novel ultra-wideband (UWB) printed monopole microstrip patch antenna is presented. The UWB is provided by using unequal V-shaped slot arms to provide staggered resonance frequencies from different couplings. Second, using modified ground plane to enhance the bandwidth. An impedance bandwidth from 2 to 30 GHz is obtained using HFSS® with discontinuities in this bandwidth. For further enhancement in the bandwidth, antenna gain as well as removing the harmonic frequencies, the embedded electromagnetic band-gap (EBG) structure is used. The impedance bandwidth reaches 2000%, covering the frequency range 0.5–40 GHz with bandwidth ratio of 80:1. Three different techniques of metamaterial are used, namely using embedded square shapes as artificial magnetic conductor, using embedded uniplanar square EBG structure without via, and, finally, using embedded metallo-electromagnetic band-gap structure with via. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2203–2209, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25447

System Modeling and Analysis for an Efficient Resource Allocation in MC-CDMA Cellular Wireless Networks to Support Internet Traffic

The Internet traffics are bursty and irregular, whereas the flow of traffic is asymmetric between up and down stream. The Multi Carrier Code Division Multiple Access (MC-CDMA) system with time division duplex mode, employing unequal slot allocation between uplink and downlink, is a promising solution for these requirements. In this paper, we model and analyze the effect of an asymmetric slot management strategy employing adaptive resource allocation in a MC-CDMA system, in which each cell has its own slot allocation policy based on the level of traffic load. The bit error rate (BER) of MC-CDMA considering four cases of uplink and downlink between cells is simulated separately in the presence of Additive White Gaussian Noise (AWGN) and Rayleigh channel. The simulation result shows that the distance ratio and orthogonality factor plays a major role in computation of signal to interference ratio (SNR), and hence the BER performance. We also estimate the loading of subcarrier (b/s per Hz) for a given traffic distribution.