Compact ultra-wideband planar tapered slot antenna for use in a microwave imaging system

The design of an ultra-wideband planar tapered slot antenna for use in a circular cylindrical microwave imaging system is pre-sented. The antenna was designed assuming high dielectric substrate material Rogers RT6010LM to achieve its compact size. The developed antenna element (50 X 50 mm(2)) features a 10-dB return loss bandwidth from 2.75 GHz to more than 11 GHz. The gain of the antenna is between 3.5 and 9.4 dBi over the 3-10 GHz band. The experimental tests showed that the manufactured antenna element supports transmission of narrow pulses with negligible distortions, as required in the microwave imaging system. (c) 2006 Wiley Periodicals, Inc.

Investigations into a dual band 2.4/5.2GHz antenna for WLAN applications

The design of a dual-band 2.45/5.2 GHz antenna for an access point of a wireless local area network (WLAN) is presented. The proposed antenna is formed by an assembly of a radial line slot array (RLSA) operating at 2.4 GHz and a microstrip patch working at 5.2 GHz. The design of this antenna system is accomplished using commercially available finite element software, high frequency structure simulator (HFSS), of Ansoft. The performance of the designed antenna is assessed in terms of return loss (RL), radiation pattern and polarization purity in the two investigated frequency bands.

A planar UWB antenna with signal rejection capability in the 4-6 GHz band

The design of a compact planar antenna featuring ultra wideband performance and simultaneous signal rejection in the 4-6 GHz band, assigned for IEEE802.11a and HIPERLAN/2, is presented. The design is demonstrated assuming RT6010LM substrate with a relative dielectric constant of 10.2 and thickness of 0.64 mm. The presented results show that the designed antenna of 27 mm * 20 mm dimensions has a bandwidth from 2.7 GHz to more than 10 GHz excluding the rejection band. The antenna features near omnidirectional characteristics and good radiation efficiency.

Reducing the height of a circular array of monopoles using top hats and dielectric coatings

Using a Radial Guide Field Matching Method, an investigation is performed into reducing the height of an electronically steered circular array of monopole antennas composed of a central active element surrounded by passive elements being either short- or open-circuited. It is shown that a considerable height reduction can be achieved using top hats attached to monopoles ends and by applying dielectric coating underneath the top hats. The trade-off in achieving height reduction is narrower impedance bandwidth.

Investigations into a wideband spatial beamformer employing a rectangular array of planar monopoles

This paper presents a rectangular array antenna with a suitable signal-processing algorithm that is able to steer the beam in azimuth over a wide frequency band. In the previous approach, which was reported in the literature, an inverse discrete Fourier transform technique was proposed for obtaining the signal weighting coefficients. This approach was demonstrated for large arrays in which the physical parameters of the antenna elements were not considered. In this paper, a modified signal-weighting algorithm that works for arbitrary-size arrays is described. Its validity is demonstrated in examples of moderate-size arrays with real antenna elements. It is shown that in some cases, the original beam-forming algorithm fails, while the new algorithm is able to form the desired radiation pattern over a wide frequency band. The performance of the new algorithm is assessed for two cases when the mutual coupling between array elements is both neglected and taken into account.

Receiving mutual impedance between two normal-mode helical antennas (NMHAs)

A new mutual impedance - the receiving mutual impedance - between two normal-mode helical antennas is defined, measured, and theoretically calculated. The variations of the receiving mutual impedance with antenna separation, with frequency, and with excitation source direction are critically investigated. An application of the receiving mutual impedance in direction finding demonstrates its more accurate description of the mutual coupling effect than that using the conventional mutual impedance.

A passive reflect array with dual-feed microstrip patch elements

The design, development, and testing of an X-band 137-element passive reflect away capable of incorporating active devices such as transistor amplifiers is presented. In order to avoid grating lobes in the radiation pattern, the interelement spacing is minimized using dual-feed aperture-coupled patch antenna elements. Far-field radiation pattern results are presented and compared with the predicted radiation patterns. (C) 1999 John Wiley & Sons, Inc.

A dual band 2.4/5.2GHz antenna including a radial line slot array and a patch

The design of an antenna that combines a radial line slot array and a circular patch to operate as a dual band (2.4/5.2 GHz) antenna at the access point of a WLAN is presented. The design has been accomplished using commercially available Ansoft HFSS and in-house developed software. The designed antenna shows good performance in terms of return losses, radiation pattern and circular polarization in the two, 2.4 and 5.2 GHz, frequency bands. Due to its good electrical performance and a relatively low profile and low developmental cost, it should be found attractive for use as an access point antenna for dual band operation.