Bandwidth enhancement for microstrip patch antenna using stacked patch and slot

Small size wideband microstrip patch antenna with slot in ground plane and stacked patch fed through microstrip line is presented. By inserting slot on ground plane and stacked patch supported by wall, the bandwidth can improve up to 25% without significant change in the frequency. The bandwidth before adding the slot and the stacked patch was 3.72%, whereas after adding the slot and the stacked patch the bandwidth increased up to 25% ranging from 2.45 to 3.3 GHz. The radiation pattern has acceptable response at both E-plane and H-plane. The ground plane size is 30 mm by 90 mm, the antenna designed is based on Roger RT/duroid 5880 with dielectric constant 2.

Travelling-wave similarity solutions for an unsteady shear-stress-driven dry patch in a flowing film

We investigate unsteady flow of a thin film of Newtonian fluid around a symmetric slender dry patch moving with constant velocity on an inclined planar substrate, the flow being driven by a prescribed constant shear stress at the free surface of the film (which would be of uniform thickness in the absence of the dry patch). We obtain a novel unsteady travelling-wave similarity solution which predicts that the dry patch has a parabolic shape and that the film thickness increases monotonically away from the dry patch

Rethinking the Patch Test for Phase Measuring Bathymetric Sonars

While conducting hydrographic survey operations in the Florida Keys, NOAA Ship Thomas Jefferson served as a test platform for the initial operational implementation of an L-3 Klein HydroChart 5000 Swath Bathymetry Sonar System1 , a hull-mounted phase measuring bathymetric sonar (PMBS). During the project it became apparent that the traditional patch test typically utilized for multibeam echosounder (MBES) systems was poorly suited to the HydroChart – and perhaps other PMBS systems as well. These systems have several inherent characteristics that make it difficult to isolate and subsequently solve for biases under the traditional patch test paradigm: presence of a nadir gap, wide swaths (typically greater than 6 times water depth), and relatively poor object-detection capability in the outer swath. After “rethinking” the patch test to account for these characteristics, the authors propose a new patch test paradigm that is better suited to the HydroChart and other PMBS systems

Reconfigurable dual band microstrip patch antenna for software defined radio applications

In this paper, a reconfigurable microstrip patch antenna with RF pin diode switches is implemented for dual band of 2.4 GHz and 5.6 GHz Software Defined Radio (SDR) applications. For the dual band SDR system, the use of a single antenna with a wide bandwidth to cover both of the bands can be limiting for low power level signal applications due to wideband noise. A reconfigurable nested microstrip patch antenna is designed on a Rogers 5880 RT/DUROID substrate which is fed by a coaxial probe from the back side of the grounded substrate. RF switching circuitry involves four RF pin diodes at each side of the inner patch. The dual bands of 2.4 GHz and 5.6 GHz frequency operation can be simply obtained by switching the PIN diodes on and off. The antenna is well matched and achieves approximately 7 dBi simulated gain at both frequency bands. Simulation results show that the nested patch antenna is suitable for dual band SDR applications

Gridded circular patch antennas

The performance of circular microstrip patch antennas is presented where the conducting patch and ground plane are constructed from a grid. Improved cross polarization, mode suppression, and band-width are possible, but are accompanied by lower gain and reduced front-to-back ratios. A computer simulation reveals the current structure. The density and shape of the grid pattern are important parameters. Such antennas are can be manufactured within glass laminates. (C) 1999 John Wiley & Sons, Inc

An adaptive microstrip patch antenna for use in portable transceivers

This paper describes an adaptive frequency tunable microstrip patch antenna. The introduction of an adaptive feedback loop enables the patch antenna to optimise the antenna-feed impedance match. As a result, the performance of the antenna is less affected by external disturbances such as coupling to nearby objects. Measurements evaluating the performance of the proposed antenna, in terms of transmitted power and bit error rate, are presente