Wall surface wave effects in WLAN propagation environments

2003 ◽  
Vol 39 (3) ◽  
pp. 267 ◽  
Author(s):  
J.R. James ◽  
I.L. Morrow ◽  
P. Cushnaghan ◽  
A.S. Fairweather
Keyword(s):  
Surface Wave ◽  
Wall Surface ◽  
Wave Effects

Surface-wave effects with large antenna earth screens

1969 ◽  
Vol 5 (22) ◽  
pp. 552
Author(s):  
J.R. Wait
Keyword(s):  
Surface Wave ◽  
Wave Effects

A Technique of Scan Blindness Elimination for Planar Phased Array Antenna using Miniaturized EBG

2014 ◽  
Vol 69 (2) ◽  
Author(s):  
M. S. M. Isa ◽  
R. J. Langley ◽  
S. Khamas ◽  
A. A. M. Isa ◽  
M. S. I. M. Zin ◽  
...  
Keyword(s):  
Surface Wave ◽  
Band Gap ◽  
Radiation Pattern ◽  
Phased Array ◽  
Elevation Angle ◽  
Array Antenna ◽  
Phased Array Antenna ◽  
Electromagnetic Band Gap ◽  
Novel Technique ◽  
Wave Effects

In this paper, the planar phased array antenna scan blindness characteristic has been analyzed and a novel technique of eliminating the scan blindness for the phased array antenna has been introduced. The scan blindness of the center element has been used to present the entire phased array characteristic. The array scan blindness characteristics have been simulated and analyzed using CST Microwave Studio (CST MWS). The 5×3 planar phased array antenna radiation patterns against the pattern elevation angle direction has been simulated and compiled. The array’s scan blindness has been determined at the angle of approximately 47⁰. The miniaturized capacitive loaded Electromagnetic Band Gap (EBG) has been developed and introduced between the array elements to eliminate the problem. Based on the simulated results, it is shown that the use of a miniaturized EBG is effective in reducing the surface wave effects and eliminates the scan blindness in the array radiation pattern. This novel finding is very useful to improve the antenna directive efficiency for the directional radar and satellite application.

Surface wave effects on bottom geoacoustic inversions

2017 ◽  
Vol 142 (4) ◽  
pp. 2590-2590 ◽  
Author(s):  
Ying-Tsong Lin ◽  
Timothy F. Duda ◽  
Arthur Newhall ◽  
Glen Gawarkiewicz
Keyword(s):  
Surface Wave ◽  
Wave Effects

scholarly journals Surface Wave Multipath Signals in Near-Field Microwave Imaging

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Paul M. Meaney ◽  
Fridon Shubitidze ◽  
Margaret W. Fanning ◽  
Maciej Kmiec ◽  
Neil R. Epstein ◽  
...  
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Antenna Arrays ◽  
Imaging Techniques ◽  
Near Field ◽  
Microwave Imaging ◽  
Feed Line ◽  
Receiving Antenna ◽  
Wave Effects ◽  
Multipath Signals

Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations.

scholarly journals Surface Wave Effects on the Wind-Power Input to Mixed Layer Near-Inertial Motions

2017 ◽  
Vol 47 (5) ◽  
pp. 1077-1093 ◽  
Author(s):  
Guoqiang Liu ◽  
William Perrie ◽  
Colin Hughes
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Wind Power ◽  
Mixed Layer ◽  
Single Point ◽  
Storm Track ◽  
Power Input ◽  
Momentum Fluxes ◽  
Wave Effects ◽  
Evolving Surface

AbstractOcean surface waves play an essential role in a number of processes that modulate the momentum fluxes through the air–sea interface. In this study, the effects of evolving surface waves on the wind-power input (WPI) to near-inertial motions (NIMs) are examined by using momentum fluxes from a spectral wave model and a simple slab ocean mixed layer model. Single-point numerical experiments show that, without waves, the WPI and the near-inertial kinetic energy (NI-KE) are overestimated by about 20% and 40%, respectively. Globally, the overestimate in WPI is about 10% during 2005–08. The largest surface wave effects occur in the winter storm-track regions in the midlatitude northwestern Atlantic, Pacific, and in the Southern Ocean, corresponding to large inverse wave age and rapidly varying strong winds. A relatively low frequency of occurrence of wind sea is found in the midlatitudes, which implies that the influence of evolving surface waves on WPI is intermittent, occurring less than 10% of the total time but making up the dominant contributions to reductions in WPI. Given the vital role of NIMs in diapycnal mixing at the base of the mixed layer and the deep ocean, the present study suggests that it is necessary to include the effects of surface waves on the momentum flux, for example, in studies of coupled ocean–atmosphere dynamics or climate models.

Surface wave effects on submesoscale fronts and filaments

2018 ◽  
Vol 843 ◽  
pp. 479-517 ◽  
Author(s):  
James C. McWilliams
Keyword(s):  
Surface Wave ◽  
Turbulent Mixing ◽  
Wind Wave ◽  
Surface Wind ◽  
Stokes Drift ◽  
Momentum Balance ◽  
Surface Wind Stress ◽  
Time Scale Separation ◽  
Complementary Effect ◽  
Wave Effects

A diagnostic analysis is made for the ageostrophic secondary circulation, buoyancy flux and frontogenetic tendency (SCFT) in upper-ocean submesoscale fronts and dense filaments under the combined influences of boundary-layer turbulent mixing, surface wind stress and surface gravity waves. The analysis is based on a momentum-balance approximation that neglects ageostrophic acceleration, and the surface wave effects are represented with a wave-averaged asymptotic theory based on the time scale separation between wave and current evolution. The wave’s Stokes-drift velocity $\boldsymbol{u}_{st}$ induces SCFT effects that are dominant in strong swell with weak turbulent mixing, and they combine with Ekman and turbulent thermal wind influences in more general situations near wind–wave equilibrium. The complementary effect of the submesoscale currents on the waves is weak for longer waves near the wind–wave or swell spectrum peak, but it is strong for shorter waves.

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