If an antenna is able to extract a certain amount of power from a passing wave of known power density, an effective area or aperture can be calculated and associated with it. High directivity is the main advantage of the parabolic. Possible candidates are the waveguide, ridge waveguide, helix, and slot array. A convenient figure of merit proportional to the signaltonoise ratio received by the antenna is the value of gt, in which g is the antenna gain and t is the receiving system noise temperature in degrees kelvin. It is these side lobes that can cause interference with adjacent pointtopoint links, and it is theses side lobes that must be minimized through. In more complex designs, such as the cassegrain antenna, a subreflector is used to direct the energy into the parabolic reflector from a feed antenna located away from the primary focal point. Lens antenna is used along with point source, but practically horn antennas are used at focal point. The element types determine the array gain that we can achieve. This page covers different types of antennas used in wireless communication. The lens antenna consists of twelve capacitively coupled unit cells distributed along a ring and illuminated by an openended circular waveguide with a metallic resonant ring. A commonly used directional antenna is the yagiuda array, usually just called a yagi. Design and analysis of several kinds of dielectric lens antennas.
When the feed point is moved to the shortcircuited end of the slot or inf antenna, the impedance decreases. Antenna and wave propagation pdf notes book starts with the topics covering antenna basics, thin linear wire antennas, antenna arrays. Our purpose is to optimize the performance of the lens antenna so as it has low side lob level, insertion loss and thin thickness. Variations of these factors in lenses should determine the type and quality of lens and pictures you get. To have a better understanding of the lens antenna, the working principle of a lens has to be known. Phased arrayfed reflector pafr antenna architectures. Types of antennas antenna types in wireless communication.
The parabolic reflector antennas previously discussed and the antenna shown in figure 3 are examples of parasitic arrays. Lens antenna basics and typesdielectric,metal plate lens. For many applications, there are inherent limitations that are associated with the use of these legacy antennaspayloads. Lens antenna an antenna whose directivity pattern is a result of the difference between.
Lens antenna basics and typesdielectric,metal plate lens antenna. Analysis and design of a metamaterial lens antenna using. Reflector types related features, illustrative problems unitvi objective study of lens antennas, horn antennas, and measurement of important antenna parameters. Antenna systems 4 microwave antenna systems minimizing interference by antenna design the radiated power of a microwave antenna apart the main beam at 0 deg is significant up to 90 deg from the main beam. Satellite antenna an overview sciencedirect topics. This antenna is typically a lowgain type such as a halfwave dipole or a small waveguide horn. The lens of an antenna is substantially transparent to microwave energy that passes through it. The slot antenna can be considered as a loaded version of the inf antenna.
The planar antenna used is an equiangular logarithmic spiral, which comprises 1. It was invented by shintaro uda and his colleague, hidetsugu yagi, in 1926. In general, the types having n 1 are nondispersive. Two different lens configurations are studied, one based on a dielectric slab waveguide and another based on a parallel plate waveguide. Dielectric lens antenna metal plate lens antenna dielectric lens antenna. The basics and types of antennas include horn antenna,parabolic antenna,helical antenna,slot antenna,dielectric antenna,patch antenna,phased array antenna,dipole antenna,directional antenna,folded dipole antenna,ground plane antenna,yagi antenna,log periodic antenna etc. Pdf antenna and wave propagation notes pdf awp notes sw. Here you can download the free lecture notes of antenna and wave propagation notes pdf awp notes pdf materials with multiple file links to download. Lens antenna 32825 lens antenna may be divided into two distinct types delay lenses,in which the electrical path length is increased by the lens medium fast lenses,in which the electrical path length is decreased by the lens medium dielectric lenses and hplane metalplate lenses are of the delay type. Equations explaining lens geometry in the 1st scenario are. As shown spherical wavefront produced by primary feed antenna is. Lens target output can range from a simple collimated beam increasing the feed directivity to more complex multiobjective specifications. A basic standard lens which sees the way our eyes see is different for different formats.
Lenses are made from materials such as glass or plastic, and are ground and polished or molded to a desired shape. Lens antenna is a microwave antenna in which a dielectric lens is. Representative lens antenna design examples are described in detail, with emphasis on. The lens and the antenna array, as a whole, are referred to as the n element lens antenna. Antenna is described by the curve if want to scale frequency operation by 1k need new surface relaxed criterion.
Spherical lens antennas are attractive antennas for such moving vehicles as each pencilbeam, originating from one feed antenna, can be scanned by moving the feed around the surface of the lens. A normal glass lens works on the principle of refraction. Here the transmission line is connected to source or generator at one end. The antennas commonly used for lmrboth at base stations and mobile unitsrepresent only a very small portion of all the antenna types. In most cases the target radiation pattern continues to be the collimated beam type plane wave output either fixed or scanning. It will, however, cause the waves of energy to be either converged or diverged as they exit the lens. Likewise, if a linear wire antenna develops a certain.
Ec 308 awp ch10 lens antenna free download as powerpoint presentation. A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. Syallabus lens antennas introduction, geometry of nonmetallic dielectric lenses, zoning, tolerances, applications. The design of square loop antenna is exactly same as for the folded dipole antenna except the distance between the two conducting wires of the. The conducting type of lens is illustrated in figure 110, view a. The total length of the antenna horn and lens is 78 mm. Antenna types antennas can be classified in several ways. Such a shaped dielectric lens can be more economical to produce in small to mediumscale production runs than other antenna types where certain niche. Antennas and propagation slide 29 chapter 4 spiral antennas general conditions for frequency independence consider geometry in spherical coordinates input terminals infinitely close to origin at.
The lens and reflector are used as collimating elements in a highgain antenna system. Types of antennas isotropic antenna idealized oradiates power equally in all directions dipole antennas ohalfwave dipole antenna or hertz antenna oquarterwave vertical antenna or marconi antenna parabolic reflective antenna oused for terrestrial microwave and satellite applications olarger the diameter, the more tightly directional is the. L e n sa n t e n n a 2 types in this type of lens antenna, spherical. Elliptic and hyperbolic dielectric lens antennas in mmwaves. Lens antenna article about lens antenna by the free. The integrated antenna consists of a planar spiral antenna mounted on the flat surface of an extended hemispherical lens. This chapter presents the integrated lens antenna ila technology as it evolved since its introduction aiming to respond to the needs of emerging applications such as highdatarate communication. Along the uniform part of the line energy is guided as plane tem wave with little loss. In most cases, the target radiation pattern continues to be the collimated beam type plane wave output, either fixed or scanning.
The theory of characteristic modes is used to analyze the metamaterial lens, in order to provide an insight into the. The antenna equations which follow relate to figure 1 as a typical antenna. Analysis of spherical lens antennas comparison of three. Lens antenna is a microwave antenna in which a dielectric lens is placed in front of the dipole or horn radiator to concentrate the radiated energy into a nar slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. An isotropic antenna isotropic radiator is a hypothetical antenna that radiates equal signal power in all directions. A single driven element, typically a dipole, propagates rf energy. No real antenna can have an isotropic radiation pattern, but the isotropic radiation pattern serves as reference for comparing the radiation. A yagi antenna uses several elements to form a directional array.
For frequencies above k uband the penalty in weight and size associated with a lens is relatively small. The lens integrated antennas have been previously investigated by various researchers as 5. Yagiuda antenna, micro strip patch array, aperture array, slotted wave guide array used for. The recent advent of millimeterwave technology and the increasing demand for higher frequencies have stimulated a renewed interest in the design of lens antennas for radar and communication systems. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses elements, usually arranged along a common axis. A new singlelayer metamaterial lens antenna aimed to operate at 10 ghz is proposed in this paper. Others include physical structure and electricalelectromagnetic design. Both analyzed types of lenses elliptic and hyperbolic proved to have specific advantages and drawbacks that are going to be detailed in the following text. The following types of lens antennas are available dielectric lens or hplane metal plate lens or delay lens travelling. In figure 1, bw n is the azimuth beamwidth an d bw 2 is the elevation beamwidth. The frequency range of usage of lens antenna starts at mhz but its use is greater at 3000 mhz and above. It is a mathematical model that is used as the base of comparison to calculate the directionality or gain of real antennas.