There are many different types of microstrip patch antennas, and many of them can be found in the MicrowaveTools Antenna A-Z database. All the equations for determining the size and impedance of an inset fed patch antenna are at the end of this post.
Matlab scripts are provided. A well designed patch antenna can have a peak gain between 6 and 8dBi, and as such it is considered to have a directional pattern click to rotate 3D image below which is linearly polarized along the width of the patch. The rectangular patch is one of the more common types of patch antennas. This antenna is designed using a rectangular piece of electric conductor situated above a ground plane. The rectangular piece of copper measures long. Note that the wavelength depends on the material situated between the ground plane and the patch; meaning when air is between the patch and ground, the length of the rectangle electric conductor is of the free-space wavelength.
If the antenna is loaded with different dielectrics, the length of the antenna decreases as the dielectric constant increases. The natural input impedance of a patch antenna dependent on where within the patch the feed is located.
If the feed is located closer to the edge of the patch the input impedance will be high, if the feed is located closer to the center of the patch the impedance will be low. Below is the standard input impedance of an inset fed patch antenna at 2. This type of antenna is inherently a high Q antenna, meaning that this antenna is relatively narrow banded. There are many different ways to feed a patch antenna, the inset fed patch antenna is fed via a microstrip feed line connected to a specific point within the patch.
Through varying the location of where the microstrip connects to the patch antenna the measured input impedance can be controlled. The Microstrip patch antenna is a little different than many antennas, as the structure itself does not radiate, but rather the edge gaps between the patch and the ground plane.
This can be visualized below. The areas where the patch radiates from are shown below. The patch antenna radiates from the side in which it is fed and the opposite side. This creates a skew in the pattern, causing the boresight of the antenna not being located exactly normal to the planar surface of the patch antenna.
This means that it is not possible to make an inset patch radiate with circular polarization without using four feeds. The inset patch design has three distinct geometrical regions. The first is the actual patch itself. The second is the feed line. Finally, the third part is the ground plane. It is possible to derive the parameters of patch antenna using a few different techniques.
This article will focus on the cavity model approximation in most situations and will fall back on the transmission line model to derive parameters such as the input impedance of the patch. It is possible to determine the width of the patch, w, using Equation 1. The width of a patch antenna is good starting point when designing a microstrip patch antenna. This is due to the width not having a significant impact on the operational frequency of the antenna, and tends to have the largest effect on the bandwidth and the input impedance excluding dielectric height and constant of the patch antenna.
The length of the patch is determined by the electrical length of the antenna rather than the physical length of the antenna.Remember Me? Find the Input Impedance of Patch Antenna in HFSS I have gone through many threads in the forum about finding the input impedance of patch antenna, however all the replies can't catch my mind.
So, can anybody tell me the direct way to find the input impedance in the HFSS 13? It's better to teach me in step by step way. Please don't tell me to use formula, i know it should have a "direct way" to see the input impedance. Thank you very much. Originally Posted by mohamed. Create a new Smith chart report and insert your S 1,1 trace. If you add a marker to any point on your trace, HFSS should directly display the input impedance for you. I'm not clear about the "excitation of the rectangular sheet" If I want to excite a dipole patch, how does the sheet look like?
Originally Posted by nothGing. I am using the wave port to excite my patch antenna. If you are using lump port, maybe it can't work out since lump port don't have deembed setting. First, assign the excitation of the rectangular sheet as waveport. At the Deembed setting there, thick the box "deembed", and key in the distance. Originally Posted by aptaua. Thank you nothGing, but I need your help. Input impedance of a patch in HFSS 1.
Thread starter KaiL Start date Dec 10, Search Forums New Posts. Last edited: May 31, Scroll to continue with content. MrAl Joined Jun 17, 7, Hi, Perhaps you can get the formula from the first website and compare it to the other formula and see if they are similar. One possibility is that the web site did not set up the formula right so you could try that.
MrAl said:. Hi, You mean they already got the formula from the website? Tesla23 Joined May 10, The formula for G1 in that paper doesn't look right. I think the original reference for this is the paper by Carver "Practical analytical techniques for the microstrip antenna" which you can find here www. This is an approximation, it doesn't include G12, or the correction to G1 to account for the patch width.
If you include these you might get ohms, I don't know what they are claiming to calculate. The document you refer to doesn't appear to have been peer reviewed, so hasn't had much checking. Hi, That's one of the reasons i hate answering questions like this, because there are various estimates and sometimes they dont even mention that it is just an estimate and not a solid total physics based result. You must log in or register to reply here. Thread starter Similar threads Forum Replies Date How to calculate the input current through my buck converter?
Similar threads How to calculate the input current through my buck converter? How to calculate input and output capacitance in RC model.
You May Also Like. Continue to site. How to calculate the input current through my buck converter? General Electronics Chat. Dec 20, Dec 3, Feb 6, Feb 8, Jan 12, Click here to go to our main antenna page. Click here to go to our main microstrip page. Click here to go to our page on circular patch antennas new for September ! The microstrip antenna was first proposed by G. Deschamps inbut didn't become practical until the s when it was developed further by researchers such as Robert E.
Munson now in our Microwave Hall of Fame! Also referred to as microstrip antenna, or abbreviated MSA. For now we will only be discussing rectangular, single-polarization microstrip antennas, there are many other variations, enough to fill a book.
Go to our book section and we'll help you order it from Amazon. The size of a microstrip antenna is inversely proportional to its frequency.
Inset Fed Microstrip Patch Antenna
At frequencies lower than microwave, microstrip patches don't make sense because of the sizes required. At X-band a microstrip antenna is on the order of 1 centimeter long easy to realize on soft-board technology. If you wanted to make a microstrip antenna to receive FM radio at MHz it would be on the order of 1 meter long which is a very large circuit for any type of substrate!
For AM radio at KHz, the microstrip patch would be the size of a football field, utterly impractical. One everyday application where microstrip patches are used is in satellite radio receivers XM and Sirius. Here the antenna is often mounted in a vehicle, where the angle in the X-Y plane relative to the satellite is not fixed like it is for the satellite television dish mounted to your house.
Thus circular polarization is employed for satellite radio, and the angle that the patch is with respect to the satellite doesn't matter.
This is by far the most popular type of MSA. The figure below shows the geometry of the rectangular microstrip antenna, not including the ground plane and dielectric which would be underneath.
Microstrip Transmission Line Characteristic Impedance Calculator
The dimension L is universally taken to mean the long dimension, which causes resonance at its half-wavelength frequency. The radiating edges are at the ends of the L-dimension of the rectangle, which sets up the single polarization. Radiation that occurs at the ends of the W-dimension is far less and is referred to as the cross-polarization. The image below is a side view which attempts to show a snapshot of the E-field under the patch.
Note that the fields under the L-edges are of opposite polarity due to the half-wave nature of the patch and when the field lines curve out and finally propagate out into the direction normal to the substrate they are now in the same direction both facing left.Microstrip Patch Antennas or simply patch antenna are increasingly useful because the antenna is printed directly onto a circuit board. Additional benefits of patch antennas is that they are easily fabricated making them cost effective.
Their low profile design, often square or rectangular, allows them to be mounted to flat surfaces. Pasternack carries a variety of panel and patch antennas which can be seen here. Place order in next. Antenna Downtilt and Coverage Calculator.
How do we calculate the input impedance of a patch antenna from its dimension?
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Power Density Calculator. Reflection Attenuator Calculator.Remember Me? Re: how to calculate the feed point of microstrip antenna Hello. I would like to remind you that in feeding a patch antenna, the location of the feed point determines the patch's input impedance at the resonance frequency. If feeding with standard 50Ohm SMA connectors, the input impedance of the patch should be adjusted to approx.
Now keep in mind that you don't want the feed location to be neither at the edge of the patch nor at the center. The reason is that using the cavity model for analyzing the patch and assuming the dominant mode the E field is zero at the center of the patch so this would give you zero input impedance and maximum at the edges implying very high input impedance. So you generally want to be somewhere in between the edge and the middle to achieve 50Ohm.
Any book for microstrip antennas should have the formulas you need to find the location of the feed point, to obtain precisely 50Ohm input impedance. My calculation gave me that you need to place your feed at about Notice that I strongly encourage you to read the analysis of the patch antenna.
You would feel much more comfortable with your calculations!! Take care. Re: how to calculate the feed point of microstrip antenna Thank you so much for your explaination on feed point.
Re: how to calculate the feed point of microstrip antenna Hi again, So I guess you're saying that your simulated S11 is not very good? What do you mean not "good return loss"? A typical patch antenna has very good return loss right at the resonance frequency. The bandwidth though is small. If you want to make the discussion easier show me a graph of your S11 vs frequency and I can help out to fix your matching. It might be for example that the probe you made to feed the patch is not 50Ohms and that's why the patch looks missmatched.
But I'd like to see the plot to be able to help more. The ground plane does affect things a lot. But as long as you've made it larger than the patch about times larger you should be fine. If you want attach me the paper you're reading.
I'd be interested to see what they're doing. Best, Yiannis. Re: how to calculate the feed point of microstrip antenna hello again i have attached the paper and i set the grnd plane as 80mm x 80 mm. Re: how to calculate the feed point of microstrip antenna i have attached the ie3d file.
Re: how to calculate the feed point of microstrip antenna Thank you. Unfortunately, I've never used ie3d for simulations so I can't really open the file and process it But don't worry, we'll work with what we have So from what I understand, are you trying to reproduce the green curve on figure 4 of the attached paper?To browse Academia. Skip to main content.
Log In Sign Up. The calculation of the input resistance of rectangular microstrip antenna elements with various substrate thicknesses Microwave and Optical Technology Letters, Mehmet Kara. The calculation of the input resistance of rectangular microstrip antenna elements with various substrate thicknesses. He has produced empirical antenna designs Vee Several formulas based on the transmission line and the cavity model are dipoles similar to those discussed in this article.
We would combined to produce closed-form formulas for calculating the input like to thank him for sharing with us his insight into this resonant resistance of probe-fed rectangular microstrip antenna elements problem. Also, we would like to thank Dr. Karl Steinbach of with uarious relative permittiuities and thicknesses of substrates. This formula takes into account the feed-point location, the patch and the U. Army, European Research Office for his helpful substrate physical properties, the effect of radiation, the conductor, and comments.
This work was supported in part by the Joint the dielectric losses with their quality factors. I t varies 1. The configuration of a probe-fed rectangular microstrip an- 73, NO. Owing to its effects on of State, Washington, D. Maloney and G. Antennas Propagat. AP, No.
Correction, Vol. Montoya and G. An- cal thickness from 0. These methods, how- 6.