Dimitrios E. Anagnostou

A Coplanar Reconfigurable Folded Slot Antenna Without Bias Network for WLAN Applications

The design of a reconfigurable single folded slot antenna is shown. Metal strips are used in the slot to manipulate the ground size around the slot, which yields to changing the slots perimeter and thus changing the resonant frequency of the antenna. The design of a single folded slot antenna is first illustrated. Later, the design is modified to be reconfigurable. The resonant frequencies for the reconfigurable design are chosen to be applicable with the WLAN applications. The antenna design, simulation, and measurements are described. The simulated results both for the return loss and maximum gain agree with the measurements. The antenna has similar radiation patterns in both bands. The advantage of this design is that the length of the bias lines does not affect the antenna performance, thus making its design, feeding, and matching an extremely simple and low-cost procedure for antenna designers.

The design of reconfigurable planar log-periodic dipole array (LPDA) using switching elements

This paper shows the design of a reconfigurable log periodic dipole array antenna (LPDA). The design is based on utilizing switches and high resistive DC bias lines to achieve the reconfigurable LPDA. The operating frequency and maximum directivity of the design can be manipulated according to the switches positions and their state (‘on’ or ‘off’). The simulated and measured results of the return loss and gain responses are shown. The results are promising for the implementation of such new reconfigurable antenna designs.

A 0–55-GHz Coplanar Waveguide to Coplanar Strip Transition

A broadband coplanar waveguide (CPW) to coplanar strip (CPS) transmission line transition directly integrated with an RF microelectromechanical systems reconfigurable multiband antenna is presented in this paper. This transition design exhibits very good performance up to 55 GHz, and uses a minimum number of dissimilar transmission line sections and wire bonds, achieving a low-loss and low-cost balancing solution to feed planar antenna designs. The transition design methodology that was followed is described and measurement results are presented.

A Compact CSRR-Enabled UWB Diversity Antenna

The purpose of this letter is to introduce a compact ultrawideband (UWB) diversity antenna with a very low envelope correlation coefficient (ECC). The design employs a hybrid isolation enhancing and miniaturization technique. The antenna consists of two counter facing monopoles, and is miniaturized by using not only inverted-L stubs but also a complementary split-ring resonator (CSRR) on the ground plane. The added components enhance isolation and enable tighter packing of the antennas. The result is a very compact multiple-input–multiple-output (MIMO) array with an overall size of 23

A low-cost WLAN “Green” PIFA antenna on eco-friendly paper substrate

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Dual band-notched ultra-wideband antenna for 802.11a WLAN Environments

29 mm2 , which covers the entire UWB spectrum from 3 to 12 GHz, with mutual coupling lower than –15 dB. Moreover, the CSRR unit that acts as a resonator is applied for the first time to suppress the interference of RF currents flowing through the ground plane of this UWB-MIMO/diversity antenna. The performance of the fabricated prototype in terms of scattering parameters, broadside (peak) gain, radiation patterns, efficiency, and ECC is presented and discussed.

Conformal antenna on LCP for sensor applications

This work shows for the first time the practical application of paper as a substrate in real-life wireless local area network (WLAN) applications. Photographic paper is used here in the design, fabrication and testing of a printed inverted F-antenna (PIFA) operating at 2.45GHz. Although paper substrates exhibit relatively high dielectric losses (tanδ ∼ 0.07 at 2.45GHz), the maximum gain achieved by the fabricated antenna is +1.2 dBi and its total simulated efficiency is approximately 82% at resonance. The simulation results of the return loss, as well as the radiation pattern of the antenna agree with the corresponding measured results that are presented in this work.

Mutual coupling between coax-fed rectangular microstrip antennas embedded in layered uniaxial anisotropic dielectrics

Band-reject UWB antennas have recently been considered for efficient communication between devices in WLAN environments. In this work, a new concept of a dual band-reject antenna is investigated. The antenna rejects efficiently the 802.11a interfering signal at two narrowband frequency ranges, while it receives the UWB signal in between them. Designs and simulation and measured results are presented in this work.

A printed paper-based inverted F-antenna (PIFA) for WLAN applications

The design of a novel conformal antenna that demonstrates dual-band operation and nearly omni-directional radiation patterns at the frequencies of operation is introduced in this paper. The antenna is a combination of two monopole antennas; a broadband fat monopole and a folded linear monopole. The antenna is designed on conformal liquid crystal polymer (LCP) material and a styrofoam box is used to support the structure. The antenna can be used for WLAN applications since the bands of operation overlap with the designated frequency ranges for IEEE 802.11 a and IEEE 802.11b protocols. The conformal antenna can be used for applications where the available surface for the front end is limited or when a solid compact three dimensional sensor is needed. The effect of the three dimensional geometry characteristics on the radiation pattern orientation is briefly discussed.

Beam-Shaping of Planar Array Antennas Using Integrated Attenuators

The mutual coupling between two coax-fed rectangular microstrip antennas embedded in uniaxial anisotropic dielectrics is evaluated. An interesting trade-off is shown where an increase in the permittivity in the direction of the optical axis in the substrate reduces the traditionally stronger E-plane coupling while it increases the traditionally weaker H-plane coupling. The computations from the commercial software used in this work are validated by successful comparison with published results.