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A U‐slot loaded single‐layer compact shorted‐patch antenna is presented for wireless communications in the 5.8 GHz band. The size of the prototyped antenna is only 30 mm × 30 mm, which is very small compared to single‐layer antennas for the same frequency band. The measured −10 dB reflection coefficient bandwidth of the antenna is 140 MHz (5.67–5.81 GHz). The peak measured boresight gain and directivity...
In this paper, we review two new classes of superstructures for single-feed wideband resonant cavity antennas (RCAs). Both the superstructures are composed of only dielectric materials and have non-uniform permittivity in either the axial direction, i.e., perpendicular to the antenna axis, or in the transverse plane. These superstructures not only make the resulting RCAs significantly wideband, along...
A serpentine planar inverted-F antenna (PIFA) is designed for Medical Implant Communications Services (MICS) band (401–406MHz) and presented in this paper. Resonance frequency of implantable antenna is generally detuned towards lower frequency due to the proximity effect of high permittivity human tissue. In addition, biocompatible coating material on the antenna also leads frequency shifting of the...
This paper presents a planar, low-profile and low-cost resonant cavity antenna for satellite reception applications. The antenna has a total height of only 0.468X at 12GHz, and consists of a single layer metallo-dielectric superstrate. It is designed to cover the entire ITU Region 3 downlink band for Direct Broadcast Satellite (DBS) services. Numerical results demonstrate a peak directivity of 19...
A miniaturized implantable antenna, to be implanted in small animal, designed for Medical Implantable Communications Services (MICS), is presented in this paper. The proximity couple-fed technique is applied to enhance the bandwidth of the antenna to overcome the out-of-band probability of the antenna due to frequency detuning by the surrounding tissue and encapsulation. The aim of this research is...
Since the pioneering work of Von Trentini in 1956, significant improvements in the performance of electromagnetic band gap resonator antennas (ERA) have been made. The focus of this paper is on the computational models and computational efficiency related to the enhancement of 3-dB directivity bandwidth of such antennas. We explore to what extent the two unit-cell numerical electromagnetic models,...
A printed meta-surface that can reduce the electromagnetic footprint of a metallic cylinder is investigated. The meta-surface consists of a periodic width-modulated microstrip line lying on a homogeneous dielectric layer of constant thickness. When enfolded around the conformal geometry, it gives rise to an isotropic cloak wrapped around the object. Numerical analyses of the fields surrounding the...
In this paper, a Hilbert planar inverted F-antenna (H-PIFA) is presented that has been designed to be functional in the Australian 900MHz ISM band (915–928 MHz). The antenna is intended to be attached to an RFID PCB board which is further implanted under the skin of laboratory rats. The overall dimensions of the antenna including the ground plane are 25×25×7.6 mm3. Although the bandwidth of the antenna...
An electronically controlled half-width microstrip leaky-wave antenna (HW-MLWA) that can scan the main beam at a fixed frequency is presented. A technique is described to change the upper and lower limits of the beam direction without changing the scanning range itself. By varying the reactance profile at the free edge, the main beam of the proposed antenna can scan a range of 23° in discrete steps...
The effect of PIN diodes on the performance of a reconfigurable leaky-wave antenna (LWA) is studied. The PIN diode is modelled in three different ways. It is shown that the non-ideal behaviour of the PIN diodes changes the predicted return loss and radiation characteristics of the antenna compared to ideal switches.
A half-width microstrip leaky-wave antenna (HW-MLWA) is designed with forward (broadside-endfire) and backward (broadside-backfire) scanning capability. One feed and 50 Ω load are connected at each end of the radiating element with a simple feed network and controlled switches that allow the antenna to scan in both forward and backward directions. The main beam is steered at any operating frequency...
A new technique to implement fixed-frequency beam scanning using a half-width microstrip leaky-wave antenna (HW-MLWA) is presented. The main beam direction is electronically controlled by changing the reactance between the one edge of a microstrip and the ground. This is achieved through a set of patches periodically placed along the free radiating edge of the microstrip line, with the second edge...
A microstrip leaky-wave antenna (MLWA) is designed for fixed-frequency beam steering. The main beam direction of this antenna is controlled by changing the periodic reactive loading of a microstrip line. This reactive loading is provided by a set of periodic patches closely coupled to the stubs in the microstrip line. These patches can be selectively connected to the ground using PIN diodes. The proposed...
This paper presents the design of a Fabry-Perot/EBG resonator antenna which uses a self-polarizing partially reflecting surface (PRS). The PRS, consisting of an array of rectangular patches, is designed for self-generation of circular polarization. The PRS is designed for highest possible reflectivity and the best axial ratio performance for narrowband applications. Numerical simulations of the proposed...
In this paper we demonstrate the gain enhancement of a semicircular slot antenna using a multilayer frequency-selective surface (FSS). A theoretical analysis of the FSS with a UWB semicircular slot antenna is presented. The multilayer FSS provides an appropriate reflection phase to act as a reflector and is able to enhance the gain of the slot antenna. Simulations show a linear phase response from...
A method is proposed to extract the phase constant β and attenuation constant α of bounded waves in a finite periodic structure using scattering parameters. The proposed method accounts for the mutual coupling between the unitcells when computing the wavenumbers of the propagating modes. It is useful when the unit cell configuration is complex and typical eigen-mode solvers fail.
Effect on the electromagnetic bandgap (EBG) of an active, tunable, EBG structure, due to the insertion loss and other scattering parameters of active switching devices, is investigated. Active FET switches are modeled two ways, first as perfect conductors with the switch packaging and secondly as a black box with embedded scattering parameters provided by the switch manufacturer. The results obtained...
Wide-band matching of a tunable 1D periodic microwave structure, designed for fabrication in GaAs technology, is investigated. The two-layer unit cell of the periodic structure consists of a microstrip line loaded by multiple rectangular patches, which can be selectively short-circuited. The wide variation of the position of the bandgap, obtained by electrically controlled switches, induces a large...
Adequately design Frequency Selective Surfaces (FSSs) allow significant control of the phase of reflection and transmission characteristics over a wide frequency band. This property is used here to develop a multilayer FSS reflector enhancing the gain and radiation properties of antennas for ultra wideband applications. These kinds of reflectors make structures low profile by providing the flexibility...
Reflection of normally incident microwaves from a novel quasi-periodic High Impedance Surface is investigated. The quasi-periodic surface is formed by cascading similar, width-modulated microstrip line based unit cells. Parameter values in individual cells are changed to make the surface quasi-periodic. The reflections from quasi-periodic structures formed using sequences of different but similar...
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