Microstrip patch antennas consist of a metallic patch on a grounded substrate. In electromagnetics, an antennas power gain or simply gain is a key performance number which combines the antennas directivity and electrical efficiency. A microstrip or patch antenna is a lowprofile antenna that has a number of. Directivity is a measure of the concentration of radiation in the direction of the maximum. Gain and directivity enhancement of a rectangular microstrip patch. For a microstrip antenna to work, you want to think the opposite thoughts that you might want to think if you were designing a microstrip mmic. High directivity of microstrip patch antenna using. In that microstrip patch antenna array design the improvement to gain and directivity. Due to the shunt inductive effect brought by these shorting pins, the resonant frequency of the dominant mode in. A classical patch, such as a square shaped patch, presents a single lobed broadside pattern in its fundamental mode tm10 or tm01 with a low directivity.
The radiation pattern of a microstrip or patch antenna is shown above. The e and hfield halfpower 3db beamwidth was contracted by 47. Typical half wave patches have efficiencies well above 90%. The designed microstrip patch antenna with four slits and a pair of truncated corners are simulated using cadfeko for finding the electric far field radiation, gain, directivity, radiation pattern e. Gain and directivity enhancement of microstrip patch array antenna.
To have a greater directivity, an array can be formed by using these patch antennas. In addition to providing more than 6db gain compared to a conventional microstrip antenna, these metamaterialequipped antenna designs also feature increased bandwidth from 3. In this paper a simple microstrip patch antenna is designed in ads at a resonant frequency of 3. The directivity or gain of an antenna is defined as the ratio of the maximum value of the power radiated per unit solid angle to the average power radiated per unit solid angle. Without changing the original microstrip patch antenna size, the use of metamaterials made it possible to nearly double antenna directivity. Fundamental specifications of patch antennas radiation pattern a patch antenna radiates power in certain directions and we say that the antenna has directivity usually expressed in dbi. Gain of an antenna in a given direction is defined as the ratio of the intensity, in a given direction, to the radiation intensity that would be obtaine. Enhancement of gain and directivity for microstrip antenna using. To achieve the dualfrequency antenna, the conventional patch antenna is excited along the diagonal. The microstrip patch antenna first took form in the early 1970s and interest was renewed in the first microstrip antenna proposed by deschamps in 1953. A comparative study of rectangular and circular microstrip. Gain enhancement of a microstrip patch antenna using a reflecting. The directivity of patch antennas is approximately 57 db. An antenna that radiates equally in all directions would have effectively zero directionality, and the directivity of this type of antenna would be 1 or 0 db.
Structures formed of the metamaterials act like a lens for a microstrip antenna, boosting gain and enhancing the radiation pattern for greater coverage. Therefore, the design of highdirectivity microstrip patch antennas is a challenging task. The fields are linearly polarized, and in the horizontal direction when viewing the microstrip antenna as in figure 1a well see why in the next section. The proposed dual layer microstrip patch antenna has an impedance. Radiation efficiency, h, and unloaded radiation q, q o, as a functionof substrate thickness. This work is mainly focused on increasing the gain as well as reducing the size of the unidirectional patch antenna. Gain and directivity enhancement of a rectangular microstrip patch antenna using a. The operating frequency of antenna fr, at which we wish to achieve the maximum directivity, is 7 ghz. Iin the fr4 is specially for the low frequencis applications and for the higher frequencies its loss becomes dominant. The radiation pattern can be represented in either cartesian or polar coordinates, as shown in figure 1. However, conventional microstrip patch antenna suffers from low radiation gain and narrow bandwidth. Conventional single element microstrip patch antennas have a low directivity 67dbi 1. The patch is generally made up of a conducting material such as copper or gold and can take any possible shape like rectangular, circular, triangular, elliptical or some other common shape. The most common type of microstrip antenna is the patch antenna.
Enhancement of directivity of rectangular microstrip. Fractal shaped microstrip patch antenna is also implemented using the foam substrate. A patch antenna is a narrowband, widebeam antenna fabricated by etching the antenna element pattern in metal trace bonded to an insulating dielectric substrate, such as a printed circuit board, with a continuous metal layer bonded to the opposite side. Results and discussion several parameters like gain, directivity, radiation efficiency and return losses of antenna with transmission line are simulated and compared between conventional mpa and dng based mpa is discussed below. The transmission line model, combined with the measured and computed thermal plots, suggest a model for the computation of radiation patterns of a rectangular microstrip patch antenna in the tm 01 mode. Highdirectivity microstrip antennas comprising a driven patch and at least one parasitic element placed on the same plane, operate at a frequency larger than the fundamental mode of the driven patch in order to obtain a resonant frequency with a highdirectivity broadside radiation pattern.
In a receiving antenna, the gain describes how well the antenna converts radio waves arriving from a. Yagilike microstrip patch antenna with high directivity and large bandwidth james a. In addition, as the substrate thickness increases, the radiation q of the antenna decreases. It is a measure of how directional an antennas radiation pattern is. The beamwidth is similar in both the x and y planes, creating roughly a cone of radiation outward from the patch. Analysis and design of circular microstrip patch antenna at 5. As a transmitting antenna, the gain describes how well the antenna converts input power into radio waves headed in a specified direction. Highgain circularly polarized microstrip patch antenna. Rtduroid substrate is costlier than lcp liquid crystal polymer but rtduroid gives better performance in term of gain, directivity and bandwidth 4. Improving microstrip patch antenna directivity using ebg. Demonstration of an xband multilayer yagilike microstrip. The electric far field of the microstrip patch antenna is shown in figure. Gain and directivity enhancement of rectangular microstrip. The simulation results show that the gain, directivity and s11 parameter of the antenna with ebg cover are increased at x band 812ghz.
This video clearly explains how to extract different results from a simulated antenna return loss, gain, vswr, directivity, radiation pattern. Sometimes the antenna gain is given with reference to a dipole antenna and is labelled as dbd. The antenna gain with reference to an isotropic source is given in dbi decibel above isotropic source. The radiation pattern of microstrip or patch antenna is broad. The results shows that the directivity is enhanced by 56% as compare to conventional rectangular patch antenna.
Octagon metamaterial, gain, directivity, microstrip antenna, double. Gain and directivity enhancement of rectangular microstrip patch. Microstrip antennas have found widespread applications for microwave as well as millimeter wave systems. We used hfss high frequency structured simulator software for simulation of antenna and to find out the results. A low profile, unidirectional, dual layer, and narrow bandwidth microstrip patch antenna is designed to resonate at 2. Microstrip patch antenna array design to improve better. Making the ground plane larger also increases the gain, but as the ground plane size. The proposed antenna is suitable for specific applications, such as security and military systems, which require a narrow bandwidth and a small antenna size. The effect of changing substrate material and thickness on. Gain enhancement of a microstrip patch antenna using a. The input impedance, gain and radiation pattern of the efield and h were. A microstrip or patch antenna is a lowprofile antenna that has a number of advantages. A microstrip or patch antenna operates in a way that when current though a feed line reaches the strip of the antenna, then electromagnetic waves are generated.
Often microstrip antennas are also referred to as patch antennas. The return loss, radiation pattern and directivity are studied using hfss software. A comparative study of rectangular and circular microstrip fed patch antenna at 2. Keywords directivity, rectangular microstip antenna, ie3d, vswr i. The presence of arrays of microstrip elements provides greater directivity, higher gain, increased transmission range with less interference. Normalized radiation pattern for microstrip patch antenna. Design and analysis of microstrip patch antenna arrays. Rr radiation restance rddisspation resistance rr is calculated by. Heres a rule of thumb for antenna gain of a narrowbeam reflector antenna. The simulation results show that the gain, directivity and s11 parameter of the. By suppressing backwardwave radiation, antenna gain increased by 3. The outcomes indicate that dng based mpa has enhanced performance as far as directivity, gain and radiation efficiency of antenna. The 3dimensional plot of the gain of an antenna is known as the radiation pattern. Two sets of metallic pins are symmetrically placed along the two orthogonal diagonals of a square patch radiator at first.
A slotted rectangular microstrip patch antenna for bandwidth enhancement which is excited by two different feeding methods is presented in this. Gain is equal to directivity times efficiency, or directivity plus efficiency when expressed as db. The fundamentals of patch antenna design and performance. The radiating elements and the feed lines are usually photo etched on the dielectric substrate. Design and implementation of patch antenna 8 figure 2. If the antenna had a 100% radiation efficiency, all directivity would be converted to gain.
Thus the microstrip patch radiation intensity depends on what direction you are facing it from it has gain and directivity. The basics of patch antennas, updated orban microwave. The proposed microstrip patch antenna is realized on the roger rtduroid substrate with permittivity. The maximum value of directive gain is the directivity d of the antenna. Gain and directivity enhancement of microstrip antenna loaded with.
Metamaterial enhances microstrip antenna gain microwaves. The array gain, dipolelike directivity and unidirectional characteristic are combined for approximately 8 to 9 dbi gain approx. It is promising to reduce the lateral radiation and obtain an enhanced directivity when the sng mtms are applied in the microstrip patch antenna. Micro strip patch antenna, radiation pattern, ansoft hfss high frequency structural simulator and rogers rtduroid 5880. Thus, impedance bandwidth increases with increasing substrate thickness. Thus if you double the diameter of an aperture, or double the frequency of operation, you will quadruple the gain increase by 6 db. The mtm superstrate can modify the radiation pattern and exhibit gain. Lee national aeronautics and space administration glenn research center cleveland, ohio 445 kevin lambert analex corporation brook park, ohio 44142 abstract. Different substrates use in microstrip patch antennaa survey.
The driven patch, the parasitic elements and the gaps between them may be shaped as multilevel andor. The figure below shows the directivity of a patch antenna. We will discuss later in this work more parameters of the antenna in connection with microstrip patch antenna like radiation pattern, efficiency, quality factor, directivity, gain, and more. A microstrip patch that uses a thicker substrate is more efficient. What is the difference between directivity and antenna gain. While directivity is always greater than or equal to 1 0 db, antenna gain can be less than 1 0 db. Efficiency accounts for the actual losses of a particular antenna design due to manufacturing faults, surface coating losses, imperfections, impedance mismatch, or any other factor. Abstract a comparative study of rectangular and circular shapemicrostrip fed patch antennas f or bluetooth application is. It is the ratio of radiation intensity in a particular direction to the average radiated power. Enhancement of gain and directivity for microstrip antenna. It has low radiation power and narrow frequency bandwidth. The fringing fields at the edge of a microstrip antenna which radiate are centered about each edge of the. Antennas using patches as constitutive elements in an array are also possible.
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