Microstrip Antennas For Mobile Telephone Handset With Reduced Radiation Hazards

A novel antenna configuration comprised of two circular microstrip antennas (CMAs) resonating in the TMtt and TM2, modes, producing radiation characteristics suitable for a mobile telephone handset, is presented. The antennas operating at the same frequency are placed back to back with a separation comparable to the thickness of a typical handset. The radiation pattern consists of a region of reduced radiation intensity, which minimizes the radiation hazards to the user

Simple approach to determine resonant frequencies of microstrip antennas

A simple approach for accurate determination of the resonant frequencies of microstrip antennas of regular geometries is developed and presented. In this approach, a generalised empirical formula for the computation of effective dielectric permittivity is given which takes into account the ratio of the fringing area to the area of the patch. A correction to the equivalent side length of an equilateral triangular patch, previously published, is modified and a new formula is given. A correction to the effective dimensions of an elliptical microstrip antenna is also carried out. Numerical results obtained for the resonant frequencies of elliptical, circular, rectangular and equilateral-triangular microstrip antennas are in good agreement with the available theoretical and experimental results reported by others. The present approach is more efficient, simpler and more accurate

A Multi-Objective Antenna Placement Genetic Algorithm for Matched Array Synthesis on Complex Platforms

A Multi-Objective Antenna Placement Genetic Algorithm (MO-APGA) has been proposed for the synthesis of matched antenna arrays on complex platforms. The total number of antennas required, their position on the platform, location of loads, loading circuit parameters, decoupling and matching network topology, matching network parameters and feed network parameters are optimized simultaneously. The optimization goal was to provide a given minimum gain, specific gain discrimination between the main and back lobes and broadband performance. This algorithm is developed based on the non-dominated sorting genetic algorithm (NSGA-II) and Minimum Spanning Tree (MST) technique for producing diverse solutions when the number of objectives is increased beyond two. The proposed method is validated through the design of a wideband airborne SAR

Investigations on the Radiation Characteristics of Broadband Strip Loaded Slotted Microstrip Antennas

With the recent progress and rapid increase in mobile terminals, the design of antennas for small mobile terminals is acquiring great importance. In view of this situation, several design concepts are already been addressed by the scientists and engineers. Compactness and efficiency are the major criteria for mobile terminal antennas. The challenging task of the microwave scientists and engineers is to device compact printed radiating systems having broadband behavior, together with good efficiency. Printed antenna technology has received popularity among antenna scientists after the introduction of microstrip antenna in 1970s. The successors in this kind such as printed monopoles and planar inverted F are also equally important. Scientists and Engineers are trying to explore this technology as a viable coast effective solution for forthcoming microwave revolution. The transmission line perspectives of antennas are very interesting. The concept behind any electromagnetic radiator is simple. Any electromagnetic system with a discontinuity is radiating electromagnetic energy. The size, shape and the orientation of the discontinuities controls the radiation characteristics of the system such as radiation pattern, gain, polarization etc. It can be either resonant or non resonant structure.

A Novel Method for Switching and Tuning of PBG Structures

Photonic band-gap (PBG) structures are utilized in microwave components as filters to suppress unwanted signals. In this work, rectangular perforations were created in the ground plane of a microstrip line to construct a PBG structure. A gold-coated alumina substrate was utilized to switch or tune the bandstop characteristics of this structure. It was demonstrated that the bandstop characteristics were switched off from - 35 to - 1 dB at 16 GHz. Tuning of the bandstop edge with a shift of 1.5 GHz was also shown

Analysis of Cavity Backed Printed Dipoles

The closed form expression for the radiated power of a half-wave microstrip patch is modified to calculate the impedance bandwidth of a printed dipole. Analyses of cavity backed flared and end-loaded printed dipoles are presented

Development and Analysis of Compact AMicrostrip Antennas

The practical applications of microstrip antennas for mobile systems are in portable or pocket-size equipment and in vehicles. Antennas for VHFIUHF handheld portable equipment, such as pagers, portable telephones and transceivers, must naturally be small in size, light in weight and compact in structure. There is a growing tendency for portable equipment to be made smaller and smaller as the demand for personal communication rapidly increases, and the development of very compact hand-held units has become urgent.In this thesis work, main aim is to develop a more and more reduced sized microstrip patch antenna. It is well known that the smaller the antenna size, the lower the antenna efficiency. During the period of work, three different compact circular sided microstrip patches are developed and analysed, which have a significant size reduction compared to standard circular disk antenna (the most compact one of the basic microstrip patch configurations), without much deterioration of its properties like gain, bandwidth and efficiency. In addition to this the interesting results, dual port operation and circular polarization are also observed for some typical designs of these patches. These make the patches suitable for satellite and mobile communication systems.The theoretical investigations are carried out on these compact patches. The empirical relations are developed by modifying the standard equations of rectangular and circular disk microstrip patches, which helps to predict the resonant frequencies easily.

Investigatins on Broadband Planar Dipole Antennas

This thesis Entitled Investigations on Broadband planar Dipole Antennas. An antenna is a device ordinarily used for both transmitting and receiving electromagnetic energy. It is an integral part of the radio communication system and accounts for a good deal of progress that has been made in this field during the last few decades.The effect of flaring the dipole arms is studied in Section 4.1. It is observed that the flaring modifies the impedance characteristics of the dipole. In particular, the change in the reactive part of the impedance with frequency is controlled considerably. This improves the 2:1 VSWR bandwidth of the antenna. The effect of various other design parameters on the impedance bandwidth of the antenna are also studied. The important conclusion drawn is that, there is considerable improvement in the impedance bandwidth of the dipole when ground arm dimensions are larger than the main arm dimensions. Theoretical analysis of various cavity backed antennas are given in Chapter 6. The experimental values agree well with the computation. Also the theory gives a clear inside view and explains the reasons for bandwidth enhancement due to flaring and end-loading of the dipole arms. The percentage bandwidth is determined by calculating the Q of the antenna. Since the approach is for the analysis of microstrip antenna on thick grounded substrate, this method cannot be used to predict the impedance bandwidth of the antennas without cavity backup. Also, the structures analysed are simplified versions of the optimised ones. Specially, the arms overlapping is neglected in the analysis. Also, the antennas with symmetrical arms can only be analysed with this theory.

Broadband Cylindrical Dielectric Resonator Antenna Excited by Modified Microstrip Line

The impedance bandwidth of a high permittivity cylindrical dielectric resonator antenna excited by a micro strip line was significantly improved by modifying the feed geometry. The 10 dB return loss bandwidth is enhanced from 12 to 26% without much affecting the gain and other radiation properties of the antenna. Good agreement has been observed between the predicted and measured results

Characteristics of a Microstrip-Excited High-Permittivity Tectangular Dielectric Resonator Antenna

The radiation characteristics of a microstrip-line-excited rectangular dielectric resonator antenna (DRA) are studied experimentally.The radiation charactristics and excitation of different modes are highly influenced by the orientation of the DR,feed line parameters ,and finite size of the ground plane

Broadband Cylindrical Dielectric Resonator Antenna Excited by Modified Microstrip Line

The impedance bandwidth of a high permittivity cylindrical dielectric resonator antenna excited by a micro strip line was significantly improved by modifying the feed geometry. The 10 dB return loss bandwidth is enhanced from 12 to 26% without much affecting the gain and other radiation properties of the antenna. Good agreement has been observed between the predicted and measured results

Reactive loaded microstrip leaky wave antenna for low cost beam steering applications

A novel fixed frequency beam scanning microstrip leaky wave antenna is reported. The beam scanning at fixed frequency is achieved by reactive loading. Simulation and measured results shows frequency scanability of 80° as well as fixed frequency beam steering of 68° over the −10 dB impedance band of 4.56–5.06 GHz.

Investigations On A Microstrip Excited Rectangular Dielectric Resonator Antenna

The thesis relates to the investigations carried out on Rectangular Dielectric Resonator Antenna configurations suitable for Mobile Communication applications. The main objectives of the research are to: - numerically compute the radiation characteristics of a Rectangular DRA - identify the resonant modes - validate the numerically predicted data through simulation and experiment 0 ascertain the influence of the geometrical and material parameters upon the radiation behaviour of the antenna ° develop compact Rectangular DRA configurations suitable for Mobile Communication applications Although approximate methods exist to compute the resonant frequency of Rectangular DRA’s, no rigorous analysis techniques have been developed so far to evaluate the resonant modes. In this thesis a 3D-FDTD (Finite Difference Time Domain) Modeller is developed using MATLAB® for the numerical computation of the radiation characteristics of the Rectangular DRA. The F DTD method is a powerful yet simple algorithm that involves the discretimtion and solution of the derivative form of Maxwell’s curl equations in the time domain.

Octagon Shaped Microstrip Patch Antenna For Dual Band Applications

The paper proposes an octagon shaped Microstrip Patch Antenna suitable for dual band applications. The striking features of this compact, planar antenna are sufficient isolation between the two operating bands and an area reduction of - 29% in comparison to a conventional circular patch antenna operating in the same band

Conformal FDTD analysis of an Octagonal Microstrip Patch antenna

The recent boom in wireless communication industry, especially in the area of cellular telephony and wireless data communication, has led to the increased demand for multi band antennas. In such applications the issues to be addressed are, wide bandwidth and gain, while striving for miniature geometry. A dual frequency configuration useful in GSM1800 and Blue tooth, is one that operates with similar properties, both in terms of reflection and radiation characteristics, in the two bands of interest. Dual frequency operations can be realized by exciting the Microstrip Patch Antenna (MPA) using a single feed [1] or dual feed [2]. In this paper, Conformal FDTD[3] method with Perfect Magnetic Conductor (PMC) applied along the plane of symmetry [4] is used to study the characteristics of an Octagonal MPA. The theoretical results are compared against the experimental and IE3D™ simulated results