Slot Width (slot + width)

Distribution by Scientific Domains

Selected Abstracts

Effect of depth and width of cultivation and sowing date on establishment of red clover (Trifolium pratense L.) by rotary slot-seeding into grassland

P. Komárek
Abstract The effect of different combinations of time of sowing and depth and width of soil cultivation using a rotary slot-seeding machine to introduce red clover (Trifolium pratense) was determined for some characteristics of newly established red clover plants in a lowland Dactylis glomerata -dominated grassland in the Czech Republic. Sowing was carried out on four sowing dates in one growing season: 11 May; 21 June (after the first cut); 9 August (after the second cut); and 19 September. The experimental treatments consisted of all combinations of four depths (5, 10, 15 and 20 cm) and four widths (5, 10, 15 and 20 cm) of soil cultivation. Measurements were made of number of plants, weight and height of plants, weight and height of roots. Measurements at 2 months after sowing showed fewer seedlings for the 11 May sowing than for later sowing dates. The number of red clover plants increased as the row width was increased up to 15 cm, regardless of the depth of slot. Positive effects of slot width on weight and height of plants and weight and length of roots were recorded. A highly positive correlation was found between weight of plants and weight of roots. Width of row was the key factor for the successful establishment of seedlings into the existing sward by slot-seeding. A row width of 10 cm and depth of slot of 5 cm was considered a satisfactory combination. [source]

Characteristic analysis of reverse-L-shaped microstrip-fed large-bandwidth printed slot antenna

Yong-Woong Jang
Abstract The characteristics of a reverse-L-shaped microstrip-fed structure is analyzed using the finite difference time domain method, and the characteristics of the proposed antenna are compared with a conventional antenna. The return loss, radiation resistance, and voltage,standing wave ratio in the frequency domain are calculated by Fourier transforming the time domain results. When the proposed feed structure is used, the bandwidth is extended in proportion to the slot width and the radiation resistance has the low value. When the slot width is 16 mm, the experimental bandwidth is approximately 50% (,10 dB , S11) at the center frequency of 2.3 GHz. In addition, the experimental data for the impedance and radiation pattern of the antenna are described. They are in good agreement with the calculated results. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12, 496,502, 2002. Published online in Wiley InterScience ( DOI 10.1002/mmce.10055 [source]

Analysis and modeling of microstrip-to-coplanar flip chip package interconnects

Hussein H. M. Ghouz
Abstract In this paper, the discontinuity of a flip chip transition between a microstrip line and a coplanar waveguide is investigated and modeled using the finite-difference time-domain method (FDTD) to predict the overall S -parameters of the package. Effects of the bump and via interconnects on the package performance are investigated and discussed. This includes the effects of different staggered transitions and ground connects on the package performance. A reduction of about 10 dB in the bump and via reflections can be achieved by staggering the signal (bump) and the ground connects (bump/via). A staggering distance of about twice the slot width gave minimum reflection over a wide band of frequencies. Moreover, the larger the relative distance between the ground and the center connects the less the reflection due to the discontinuity. Finally, the computed S -parameters of the flip chip package using the FDTD solution are used to develop an equivalent circuit model for the transition discontinuity over a wide frequency band. The equivalent circuit model of the microstrip to coplanar waveguide discontinuity includes more elements and is more complex than other types of transitions. A TEE or PI circuit model has been used to approximate the general circuit model of the discontinuity. Good agreement has been obtained between the S -parameters of the FDTD model and the equivalent circuit models over a wide frequency band. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 202,211, 2001. [source]

Characteristics of a compact CPW resonant cell

Q. Xue
Abstract This paper proposes a novel structure called a compact coplanar waveguide resonant cell (CCRC), which can exhibit slow-wave and bandstop characteristics by only one single unit. The same pattern has been adopted in the compact microstrip resonant cell (CMRC) as reported previously and here is applied to CPW with both infinite and finite ground planes. Experimental results show quite good agreement with simulations. By alternating the slot width of the CCRC section from that of normal CPW, good transmitting characteristics can be achieved at a passband of low frequency. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 408,410, 2003; Published online in Wiley InterScience ( DOI 10.1002/mop.10933 [source]

A novel crossed slotted patch dual-mode bandpass filter with two transmission zeros

Sean Wu
Abstract This article presents a miniaturized dual-mode bandpass filter (BPF) with two transmission zeros and low insertion-loss using crossed slotted patch resonator. The BPF is mainly formed by a ,/2 patch resonator which is a pair of crossed slots with unequal widths is embedded in the center. By tuning the perturbation element, which resulted from the unequal slot widths along the diagonal, two resonant modes are excited and a pair of transmission zeros are generated to improve the selectivity of the BPF performance. The proposed filter at center frequency (f0) of 1.55 GHz has very good measured characteristics including the bandwidth of 1.49,1.62 GHz (3-dB fractional bandwidth of 8.4%), low insertion loss of 1.74 ± 0.35 dB. The measured filter performance is in good agreement with the simulated response. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 741,744, 2008; Published online in Wiley InterScience ( DOI 10.1002/mop.23219 [source]