Antenna Patterns and Their Meaning Much can be learned about how an antenna performs from its patterns. This paper describes many of the common antenna parameters that can be understood from the patterns. There are several different types and they all have their place. However, there can be some confusion surrounding the language used to specify antennas as well as the basic function of each type of antenna. The purpose of this white paper is to dispel the confusion surrounding antennas and their function. Section II represents the design of the suggested antenna. Design of a Corrugated Microstrip Patch Antenna with Modified Ground Plane 0491.This document is not meant to be an electromagnetic primer nor a deployment guide. Rather, it should be used as a dictionary of basic antennas and antenna terminology as well as a tutorial specifically covering antenna patterns and the parameters associated with those patterns. The focus is on many of the various antennas that might be encountered in a wireless LAN system. Along the way, the antenna patterns are shown and explained, including the 3- D radiation pattern from the antennas. Typical performance from each antenna type is described as well. Of course, there are plenty of exceptions to the . But it is often helpful to see a few examples and have some of these parameters highlighted. These antennas are shown in Figure 1. Although these antenna packages might vary somewhat from one manufacturer to another, these are typical packages for these types of antennas. The function of each of these antenna types is explained in some detail in this paper. A patch antenna (also known as a. Design of an 8X1 Square Microstrip Patch. Design of Microstrip Patch Antenna for the 2.4 Ghz Band. PATCH ANTENNAS & ASSEMBLIES. Design Considerations. Patch Antenna mounted on a ground plane with a pigtail cable to a connector. DESIGN OF LINEARLY POLARIZED RECTANGULAR. Desired Patch antenna design is initially. A microstrip antenna consists of conducting patch on a ground plane. Design and Analysis of Microstrip Patch Antenna. Design and Analysis of Microstrip Patch Antenna Arrays. 3.3 The Ground Plane 4 Chapter Four: Antenna Parameters 30. These can add a design parameter or degree of freedome that allows the performance to be tuned. The PIFA (Planar Inverted F Antenna. Various Antennas Commonly Found in WLAN Systems Historical Note: The antenna type that we commonly refer to as a Yagi was first developed in the late 1. Shintaro Uda and Hidetsugu Yagi at Tohoku University in Japan. While the antenna was mainly developed by Uda, Professor Yagi popularized the antenna design in the US and elsewhere through various conference presentations. Yagi's name has been associated with this antenna type since that time. In fact, an antenna's properties are the same in either operating mode. So, whether it is stated or not, all the definitions and descriptions describe antennas that are either part of a transmitter or a receiver. An. antenna is a transducer between a guided wave and a radiated wave, or vice versa. The radiated energy is characterized by the antenna's radiation pattern. The radiation pattern or. That is, the antenna's pattern describes how the antenna radiates energy out into space (or how it receives energy). It is important to state that an antenna radiates energy in all directions, at least to some extent, so the antenna pattern is actually three- dimensional. It is common, however, to describe this 3. D pattern with two planar patterns, called the. These principal plane patterns can be obtained by making two slices through the 3. D pattern through the maximum value of the pattern or by direct measurement. It is these principal plane patterns that are commonly referred to as the antenna patterns. Figure 2 shows a possible coordinate system used for making such antenna measurements. Inset fed Patch antenna design tutorial using CST. Home » CST Studio Tutorial » Design of Microstrip antenna in CST microwave. How big a ground plane does a gps antenna need? Typical gain and axial ratio of a patch antenna with respect to ground plane. GPS antenna ground plane design. Antenna Measurement Coordinate System. In discussions of principal plane patterns or even antenna patterns, you will frequently encounter the terms. The term. azimuth is commonly found in reference to . When used to describe antenna patterns, these terms assume that the antenna is mounted (or measured) in the orientation in which it will be used. In Figure 2, the x- y plane (. The azimuth plane pattern is measured when the measurement is made traversing the entire x- y plane around the antenna under test. The elevation plane is then a plane orthogonal to the x- y plane, say the y- z plane (. The elevation plane pattern is made traversing the entire y- z plane around the antenna under test. This gives the viewer the ability to easily visualize how the antenna radiates in all directions as if the antenna was . Occasionally, it may be helpful to plot the antenna patterns in Cartesian (rectangular) coordinates, especially when there are several side lobes in the patterns and where the levels of these side lobes are important. Any given antenna pattern has portions of the pattern that are called. In general, a. lobe is any part of the pattern that is surrounded by regions of relatively weaker radiation. So a lobe is any part of the pattern that . Figure 3 provides a view of a radiation pattern with the lobes labeled in each type of plot. Radiation Patterns in Polar and Cartesian Coordinates Showing Various Types of Lobes Isotropic radiator. An. isotropic radiator is a hypothetical lossless antenna that radiates its energy equally in all directions. This imaginary antenna would have a spherical radiation pattern and the principal plane cuts would both be circles (indeed, any plane cut would be a circle). The. gain of an antenna (in any given direction) is defined as the ratio of the power gain in a given direction to the power gain of a reference antenna in the same direction. It is standard practice to use an isotropic radiator as the reference antenna in this definition. Note that an isotropic radiator would be lossless and that it would radiate its energy equally in all directions. That means that the gain of an isotropic radiator is G = 1 (or 0 d. B). It is customary to use the unit d. Bi (decibels relative to an isotropic radiator) for gain with respect to an isotropic radiator. Gain expressed in d. Bi is computed using the following formula. Gd. Bi = 1. 0*Log (GNumeric/GIsotropic) = 1. Log (GNumeric). Occasionally, a theoretical dipole is used as the reference, so the unit d. Bd (decibels relative to a dipole) will be used to describe the gain with respect to a dipole. This unit tends to be used when referring to the gain of omnidirectional antennas of higher gain. In the case of these higher gain omnidirectional antennas, their gain in d. Bd would be an expression of their gain above 2. Bi. So if an antenna has a gain of 3 d. Bd it also has a gain of 5. Bi. The antenna simply directs the way the radiated power is distributed relative to radiating the power equally in all directions and the gain is just a characterization of the way the power is radiated. The. 3- d. B beamwidth (or half- power beamwidth) of an antenna is typically defined for each of the principal planes. The 3- d. B beamwidth in each plane is defined as the angle between the points in the main lobe that are down from the maximum gain by 3 d. B. This is illustrated in Figure 3. The 3- d. B beamwidth in the plot in this figure is shown as the angle between the two blue lines in the polar plot. In this example, the 3- d. B beamwidth in this plane is about 3. Antennas with wide beamwidths typically have low gain and antennas with narrow beamwidths tend to have higher gain. Remember that gain is a measure of how much of the power is radiated in a given direction. So an antenna that directs most of its energy into a narrow beam (at least in one plane) will have a higher gain. The. front- to- back ratio (F/B) is used as a figure of merit that attempts to describe the level of radiation from the back of a directional antenna. Basically, the front- to- back ratio is the ratio of the peak gain in the forward direction to the gain 1. Of course on a d. B scale, the front- to- back ratio is just the difference between the peak gain in the forward direction and the gain 1. The. polarization or polarization state of an antenna is a somewhat difficult and involved concept. An antenna will generate an electromagnetic wave that varies in time as it travels through space. If that wave rotates or . As a special case, if that wave spins out in a circular path, the wave (or antenna) is. This implies that certain antennas are sensitive to particular types of electromagnetic waves. The practical implication of this concept is that antennas with the same polarization provide the best transmission/reception path. If a linearly polarized antenna launches a linearly polarized electromagnetic wave traveling . Linear polarization also includes the possibility of the electromagnetic waves traveling . Often antennas can simply be physically rotated to make them horizontally or vertically polarized, although this may not always be the best choice. So a similarly polarized antenna should be used to receive these signals. This spin direction is typically characterized by left circular polarization (LCP) or right circular polarization (RCP). A dipole is usually called vertically polarized because of the way a dipole is typically used, that is, because it is mounted vertically, but the antenna is linearly polarized. Likewise, antennas that are circular in their construction do not have to be circularly polarized. Many circular patches are linearly polarized and many rectangular patches are circularly polarized. These examples are simple demonstrations of the fact that the polarization state of an antenna is not related to its shape. The. voltage standing wave ratio (VSWR) is defined as the ratio of the maximum voltage to the minimum voltage in a standing wave pattern. A standing wave is developed when power is reflected from a load. So the VSWR is a measure of how much power is delivered to a device as opposed to the amount of power that is reflected from the device. If the source and load impedance are the same, the VSWR is 1: 1; there is no reflected power. So the VSWR is also a measure of how closely the source and load impedance are matched. For most antennas in WLAN, it is a measure of how close the antenna is to a perfect 5. Ohms. The. VSWR bandwidth is defined as the frequency range over which an antenna has a specified VSWR. Often, the 2: 1 VSWR bandwidth is specified, but 1. A. directional antenna is one that radiates its energy more effectively in one (or some) direction than others. Typically, these antennas have one main lobe and several minor lobes. Examples of directional antennas are patches and dishes. An. omnidirectional antenna is an antenna that has a non- directional pattern (circular pattern) in a given plane with a directional pattern in any orthogonal plane.
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