共查询到20条相似文献,搜索用时 15 毫秒
1.
A design procedure for a circularly polarised 2 times 2 patch antenna array is presented. The structure involves 22 design parameters with associated constraints, and a multi-objective genetic algorithm is developed to determine the parameter values. This approach removes the requirement for quarter-wave transformers associated with the conventional method, and achieves a more compact configuration. In addition, the proposed design reduces step discontinuities and hence reduces spurious radiation. The related constraints were the lengths, characteristic impedance values of the array feed network and the phase-shifting between the radiating elements of the array. The return loss and axial ratio for a 5.8 GHz array were investigated and good agreement was obtained between calculated, simulated, and measured measurements. 相似文献
2.
A microstrip antenna array for circular polarisation (CP) using a proximity L-strip line feed is proposed and experimentally investigated. By placing a cross-slot with unequal slot lengths on the circular patch, circular polarisation can be excited. Also, a sequential rotation technique is adopted for the design of this CP antenna array to widen the bandwidth. The impedance and axial ratio bandwidth values are 78 and 16.15%, respectively. The boresight axial ratio is 0.4 dB at 1.91 GHz 相似文献
3.
Yazeed Qasaymeh 《International Journal of Communication Systems》2023,36(10):e5491
In this communication, the author presents an eight-element sequentially rotated (SR) circularly polarized (CP) dielectric resonator antenna (DRA) for operation in the IEEE 802.11a standard. A novel resonating element composed of a crescent slot (CS) used to excite a rectangular dielectric resonator (RDR) is proposed that has two orthogonal modes and as required for CP radiation. An SR series–parallel geometry is used to prototype the array feed network to allocate the array elements to symmetrical positions. The phase progression of each element was 45° along the array, and the signal magnitude was distributed evenly based on the binomial theory to enhance the antenna performance. The prototyped SR array had a size of mm3 and was measured and characterized in order to authenticate the design. The resonance bandwidth (S11 ˂ −10 dB) was found to be 14.28% with a 3 dB axial ratio (AR) of 17.7% for right-hand CP. The gain varied from 15.71 to 16.26 dBi within the operating band. The size, gain, and impedance bandwidth of the proposed array make it a potential candidate for devices operating in the IEEE 802.11a band. 相似文献
4.
Yao Li Ting Wang K. Fasanella 《Photonics Technology Letters, IEEE》1996,8(12):1650-1652
A 4/spl times/16 plastic array coupler for power splitting in large-core polymer optical fibers is proposed and fabricated. Maximum coupling efficiencies of up to 84.7% and 91.4% were observed using, respectively, the total internal reflection type and metal coating type micromirrors formed along polymer fibers of 1.0-mm core diameter and 0.485 numerical aperture. The coupling uniformity for the two cases were 86% and 74%, respectively. The coupling efficiency and its relation to misalignments are studied. 相似文献
5.
《Solid-State Circuits, IEEE Journal of》1976,11(6):779-783
Discusses a new 4/spl times/4 array of active bipolar transistor crosspoints realized for use in private branch telephone exchanges (PBX). It achieves low insertion loss by internal feedback and solves the interconnection problem cell by cell without a double metal layer or cross-chip bonding. Each crosspoint cell also includes a flip-flop for pulse triggering. The total number of pins is reduced to 25. The 4/spl times/4 crosspoint chip measures 3.0/spl times/2.9 mm and can easily be implemented in any higher order matrix. 相似文献
6.
Fu-Ren Hsiao Kin-Lu Wong 《Electronics letters》2003,39(11):827-828
A novel metal-plate 1/spl times/2 array antenna constructed easily from a single metal plate and suited for WLAN operation in the 5.2/5.8 GHz bands (5150-5350/5725-5875 MHz) is presented. The metal-plate array antenna comprises two radiating elements series-fed by a 50 /spl Omega/ microstrip line and excited in phase, leading to a high antenna gain level (>4.0 dBi) for frequencies across the 5.2/5.8 GHz WLAN bands. 相似文献
7.
Young Ju Lee Sung Hun Jeong Wee San Park Jae Seung Yun Soon Ick Jeon 《Electronics letters》2003,39(1):15-17
A multilayer spatial angular filter with airgap tuners to suppress the grating lobes of a 4/spl times/1 array antenna is proposed. By using the airgap tuner, a commercial standard substrate can be chosen for the filter, to achieve its resonance condition, instead of /spl lambda//sub g//4 substrate. The measured beam patterns of the 4/spl times/1 array with the filter show that the grating and sidelobes are effectively diminished by 15 to 30 dB in the region of interest. 相似文献
8.
In this paper, a compact wideband linear microstrip phased array antenna (MPAA) is proposed. To reduce the size of MPAA, a compact wideband aperture coupled microstrip patch antenna (MPA) is utilized as array element. Size reduction of the array element is performed through incorporating an interdigital capacitor (IDC) in the patch and a metamaterial (MTM) unit cell close to slot in the ground plane of the antenna. By cutting two vertical slits from the slot, further compacting of the slot in the ground plane of array element is obtained. By this technique dimensions of the patch and slot are reduced by 12.9% and 12.2%, respectively. Furthermore, dimensions of the MPAA are reduced through decreasing the spacing between array elements causing the antenna performance degradation. To overcome this shortage and improve the radiation characteristics of the proposed MPAA, an electromagnetic bandgap structure (EBG) is utilized. The effect of implementing EBG cells on the reflection coefficient of the elements in the MPAA during beam scanning is studied in details. The maximum measured gain, bandwidth and cross-polarization level of the fabricated MPAA are 13.3 dBi, 24.4% and −40 dB, respectively making it a good candidate for monopulse tracking radar applications. The measurement results confirm the simulation results. 相似文献
9.
Bouguezel S. Ahmad M.O. Swamy M.N.S. 《IEEE transactions on circuits and systems. I, Regular papers》2006,53(2):306-315
In this paper, new three-dimensional (3-D) radix-(2/spl times/2/spl times/2)/(4/spl times/4/spl times/4) and radix-(2/spl times/2/spl times/2)/(8/spl times/8/spl times/8) decimation-in-frequency (DIF) fast Fourier transform (FFT) algorithms are developed and their implementation schemes discussed. The algorithms are developed by introducing the radix-2/4 and radix-2/8 approaches in the computation of the 3-D DFT using the Kronecker product and appropriate index mappings. The butterflies of the proposed algorithms are characterized by simple closed-form expressions facilitating easy software or hardware implementations of the algorithms. Comparisons between the proposed algorithms and the existing 3-D radix-(2/spl times/2/spl times/2) FFT algorithm are carried out showing that significant savings in terms of the number of arithmetic operations, data transfers, and twiddle factor evaluations or accesses to the lookup table can be achieved using the radix-(2/spl times/2/spl times/2)/(4/spl times/4/spl times/4) DIF FFT algorithm over the radix-(2/spl times/2/spl times/2) FFT algorithm. It is also established that further savings can be achieved by using the radix-(2/spl times/2/spl times/2)/(8/spl times/8/spl times/8) DIF FFT algorithm. 相似文献
10.
Sang-Gyu Kim Kai Chang 《Electronics letters》2003,39(20):1428-1429
A new technique for realising a simple low-cost monopulse antenna using a symmetrical bi-directionally-fed microstrip patch array is described. The antenna is designed and demonstrated at Ka-band. Two squinted beams are radiated from a bi-directionally fed microstrip patch array, and a sum/difference pattern is synthesised using the in-phase and out-of-phase signals achieved using a hybrid ring coupler. The measured return loss is better than 10 dB at the sum and difference port, and the depth at broadside is more than 30 dB. 相似文献
11.
G. Giaretta M.Y. Li G.S. Li Wupen Yuen C.J. Chang-Hasnain 《Photonics Technology Letters, IEEE》1997,9(9):1196-1198
We report a novel process to fabricate single-mode independently addressable oxide-isolated vertical-cavity surface-emitting laser (VCSEL) arrays. The array is fabricated with a novel simple two-mask process where a single oxidation layer is used to define the laser aperture and to isolate the interconnects. The 4/spl times/8 VCSEL array has very uniform electrical, modal and geometrical characteristics that make it ideal for two-dimensional (2-D) array applications. 相似文献
12.
Zuo Y. Bahamin B. Tremblay E.J. Pulikkaseril C. Shoukry E. Mony M. Langlois P. Aimez V. Plant D.V. 《Photonics Technology Letters, IEEE》2005,17(10):2080-2082
We describe the design, fabrication, and testing of two packaged electrooptic switches built from poled LiTaO/sub 3/ crystals. The 1/spl times/2 switch requires a driving voltage of 1200 V and exhibits insertion loss of 2.4 dB and crosstalk of -39.2 dB; the 1/spl times/4 switch exhibits insertion loss and crosstalk of 2.8 dB and -40.6 dB, respectively, and operates using a 1100-V voltage source. The maximum deflection time between the channels is 86 ns. 相似文献
13.
14.
A novel method for radiating circular polarisation (CP) with a patch antenna without an external polariser has been investigated. It has the advantage of improving the axial ratio bandwidth for single feed CP antennas by using a thick air substrate and inverted patch configuration 相似文献
15.
16.
A 2×2 circularly polarised (CP) microstrip antenna array using a proximity coupled feed and sequential rotation is described. As compared with a previously presented single-element circularly polarised microstrip antenna with a cross-slot, the new array achieves a much wider impedance bandwidth of 11.18% and has an axial ratio bandwidth of 4.1%. The return loss, radiation patterns and axial ratio of the antenna array were measured and are presented 相似文献
17.
《Microwave Theory and Techniques》2002,50(10):2362-2367
The advantage of using a 0/spl deg/ feed structure in filter design is that two extra transmission zeros are created in the stopband while the passband response remains unchanged. This feed structure is analyzed by using transmission matrices. A new lumped-circuit model for a coupled resonator filter is then proposed to take into account the effects of this feed structure. Finally, the feed structure is applied to the design of a cross-coupled filter. All the theoretical analysis and design procedures have been successfully verified by experiment results. 相似文献
18.
《Solid-State Circuits, IEEE Journal of》1986,21(5):686-691
Through a metal option, a 256K word/spl times/1-bit and a 64K word/spl times/4-bit CMOS SRAM organization has been obtained. A fast access time has been achieved with a short bit-line structure and a data-bus precharging technique which minimize the bit-line and data-bus delay. A feedback-controlled address-transition-detector circuit has been adopted to assure the fast access time in the presence of address skew. A 1.0-/spl mu/m double-polysilicon and single-metal process technology with a polycide gate offers a memory cell size of 90 /spl mu/m/SUP Z/ and a chip size of 47.4 mm/SUP 2/. 相似文献
19.
D.L. Huffaker D.G. Deppe 《Photonics Technology Letters, IEEE》1996,8(7):858-860
Data are presented characterizing an individually addressable, multiwavelength 2/spl times/2 vertical-cavity surface-emitting laser array. The individual elements are fabricated on center-to-center spacings of 12 /spl mu/m with the lasing wavelengths controlled through the selectively oxidized lateral device sizes. Devices sized 3.5, 3.0, 2.5, and 2.0 /spl mu/m result in lasing wavelengths of 9608, 9598, 9587, and 9574 /spl Aring/, respectively. Continuous wave threshold currents of the four elements with decreasing device sizes are 240, 214, 187, and 169 /spl mu/A, respectively. 相似文献
20.
A 45/spl deg/ inclined linearly polarised slot array antenna with microstrip line feed has been developed. To simplify the feed system, series feeding is adopted to excite the radiating slots. An eight-element slot array, with an operating frequency that is of 12 GHz band, has been designed and its characteristics are investigated by the moment method analysis. Measured results are also presented to validate the numerical evaluations. 相似文献