The microstrip patch antenna is a low-profile and robust planar structure. Therefore, it has the advantage of low-cost manufacturing and a wide range of radiation patterns. However, microstrip antennas have several disadvantages, including a limited bandwidth of operation, low gain, and surface-wave losses.
A patch antenna works by creating a field between a patch’s edges. The fields from each side of a patch are polarized differently. Therefore, the voltage at one end of the patch must be higher than at the other. In other words, a patch acts as a cavity that absorbs energy and transmits it back.
Microstrip antennas are conductive strips whose width is smaller than the radiating element. This makes the antennas easier to etch on substrates. A microstrip patch antenna is often connected to a single ground plane by a coaxial feed line. Its impedance varies according to the location of the feed line in the patch.
Microstrip antennas can integrate into two-dimensional arrays. They are low-profile and cost-effective. They are also easy to fabricate. Other advantages include good conformability and low profile. They are also easily integrated with various feeding methods, including microstrip and coaxial probe.
Construction of Patch Antenna
InP substrate
An InP substrate can be helpful as a patch antenna substrate. This type of material has excellent soldering properties. We feed the proposed antenna via a 50-ohm SMA port. The proposed antenna has a transmission line structure etched from a copper layer. Silver paste connects the patch geometry to the transmission line structure. This process creates a patch antenna capable of operating at high power and low impedance.
InP substrates consist of IPTR powders rich in organic fibers. The first step in making the substrate is crushing the IPTR powders to a micro-particle size and worm water. This is followed by sizing the powders and collecting the floating ones. This process takes about two hours, after which we dry the collected powder in a convection oven. Then, we clean the remaining powder using acetone liquid, which removes the clusters of wax formed during the drying process.
The choice of material for an antenna is critical to its performance. Therefore, the choice of materials for the patch antenna significantly impacts the resulting antenna. For instance, polylactic acid (PLA) is an excellent choice for dielectric parts, while graphene is suitable for conductive components and microwaves. In addition, both materials exhibit high biocompatibility.
Dielectric material
The dielectric material is important for its performance when constructing a patch antenna. This material is a non-metal that will absorb or reflect electromagnetic waves. The dielectric material is often foam or air. The dielectric constant of these materials will affect the coupling efficiency of the antenna.
A dielectric block may help enhance the coupling between a patch and a slot. This block may vary in shape, size, and location. When properly placed and sized, the dielectric block will modify the operational characteristics of the patch. This provides substantial control over the coupling efficiency.
We construct microstrip antennas using a dielectric substrate. They are small, light, and can be printed directly onto a circuit board. They are also very versatile and easy to track. The helpful dielectric material will determine the antenna’s bandwidth and resonant frequency.
Patch
A microstrip patch antenna is circular or square antennas with the feeding end pointing into the air. A square patch antenna has a height of three centimeters (h) and a resonance frequency of 100 MHz. A microstrip antenna has the same characteristics but is much smaller and helpful at higher frequencies.
The proposed antenna is copper and coated with tin to prevent oxidation. The measured peak gain is 4.95 dB at 3 GHz and 4.88 dB at 2.95 GHz.
The Working of Patch microstrip Antenna
A patch antenna radiates as a wide, open half-wave microstrip resonator, and it consists of many individual patches arranged on a dielectric substrate. This antenna has several advantages, including a higher degree of directivity and an overall low cost. It is an ideal choice for low-frequency wireless applications.
Patch microstrip antennas radiate as wide open-open half-wave microstrip resonators
Microstrip antennas radiate as a wide open-open half-wave resonator, which is the most efficient form of antenna for transmitting wireless signals. We turn on three switches at the concentric SRR gap to tune its radiation pattern. The radiation beam becomes narrower as we turn on the switches. In contrast, the radiation beam remains wide when no switches turn on.
The wavelength of the RF signal emitted from a microstrip patch antenna is typically 96 MHz. It is designed to radiate at a frequency of 100 MHz and is resonant at 96 MHz. This is due to the fringing fields surrounding the rectangular patch antenna. A rectangular patch antenna has low bandwidth, typically less than 3%.
They provide greater directivity
Patch antennas provide more excellent directivity than dipoles because of their hemispherical radiation. They also have a smaller overall size and can be made with higher permittivity dielectrics. In addition, they can have narrower bandwidths than dipoles. This makes them a good choice for broadcast and research applications.
The directivity of microstrip antennas can increase by incorporating parasitic elements in the same plane as the feed element. An antenna incorporating such a design is suitable for broadband bandwidths, although its radiation pattern varies across the band.
They are inexpensive
Patch antennas work well in low-frequency frequencies and have a wide frequency bandwidth. They are made from copper but can also consist of other materials. These antennas can be made into different geometrical shapes, depending on size, conformity, and design consideration. Different geometries have different characteristics and are effective in achieving different frequency ranges.
A patch antenna resembles an open-circuit microstrip transmission line. Its voltage reflection coefficient is equal to one. This is because the voltage at the end of the patch is higher than the minimum voltage.
They can form with multiple patches on a dielectric substrate
We form patch antennas with multiple patches on a dielectric surface. The width of the patches is the area where waves propagate. We calculate the substrate’s dielectric substrate (ER) and the air’s ER to calculate the half-wavelength. This can help determine the effective dielectric substrate of the rectangular patch antenna. By adding a second patch, the antenna’s bandwidth can increase.
Another characteristic of microstrip antennas is their polarization diversity. They can have vertical, horizontal, and right or left-hand circular polarization. Moreover, they can have multiple feed points or only one. This makes them useful for various kinds of communication links.
They can have a higher gain on a ground plane
A patch antenna can gain higher by varying the spacing between each patch element. This allows for more gain than conventional patch antennas. This means that the elements have different phases and, thus, can steer the beam electronically.
Another feature of microstrip antennas is their polarization diversity. They can be designed with vertical, horizontal, and right and left circular polarization. They can also have multiple feed points, which makes them suitable for use in many different communications links.
Lightweight
Patch antennas are lightweight and compact, which is advantageous for space applications. We commonly fabricate them on polytetrafluoroethylene-based laminates, which provide good mechanical strength. In addition to being lightweight and compact, microstrip antenna has excellent thermal resistance. The researchers say that they can improve the performance of a microstrip patch antenna by using reinforced material.
A patch antenna can consist of conductive textiles. This is a good choice for lightweight applications, as they can integrate into clothes without being noticeable. However, a patch antenna made of textiles is still developing, so its practicality is unknown.
They can integrate with MMIC-based T/R modules
High-performance phased arrays are possible with T/R modules. However, these modules are expensive, running upwards of $1000 per unit. However, DARPA has been working to lower the cost of these modules, which should be available for consumer applications in the future. While MMIC-based T/R modules have several advantages, they are unsuitable for all applications.
An amplifier is required to amplify the signal. This is typically a ferrite circulator but can also be an SPDT switch. This allows for tuning a patch to a specific frequency.
The Radiation Pattern of Patch Antenna
The radiation pattern of a patch antenna is a function of its width and the shape of its substrate. The short-circuited ring patch produces a maximum and minimum radiation pattern on the broadside. Its size reduces by using a multilayer substrate. This antenna is also known as a “microstrip patch antenna.”
We can define the radiation pattern of a patch antenna mathematically or graphically. It results from the polar and angular directions of an electromagnetic wave. It can represent several quantities, including gain, directivity, electric field, and radiation vector.
Microstrip patch antennas can have either rectangular or circular shapes. They have different radiation patterns, but both can be helpful for wireless communications. Rectangular patch antennas are generally smaller than circular ones but exhibit a back-lobe. When designing a patch antenna, consider all factors that affect its radiation pattern. If we place the antenna correctly, it will perform well. An effective design should consider placement and size.
A patch antenna can have a rectangular, or circular metallic patch etched on a substrate. It can also have multiple patches on the same dielectric substrate. It can also have multiple feed lines, which can improve its directivity. But one drawback of a patch antenna is its relatively low radiation power and narrow bandwidth. The main advantage of a microstrip antenna is its higher directivity, but it has a lower radiation power than a patch antenna. In addition, it can be much larger if a patch antenna is combined with multiple microstrip elements.
Another common approach to reconfigure antenna patterns is to use movable antennas. This technology lets you easily rotate the radiation pattern and adjust the reflection coefficient without a bulky mechanical structure. In addition, a movable antenna can be fabricated at the microscale using MEMS technology.
Applications of Patch Antennas
A microstrip antenna are small antennas that are often helpful in wireless communications. The input resistance of a patch antenna tunes by shifting the RTD post away from its center. As a result, the input resistance is proportional to sin2(px/L). In addition, we supply a bias voltage to the RTD post at the patch’s center null point. In some cases, a parallel resistance is placed between the bias supply lines and the patch to prevent parasitic oscillation due to return pass.
Microstrip patch antennas
Microstrip patch antennas are a type of antenna that uses a metallic patch printed on a substrate. The patch is usually fed by a stripline or coaxial probe, with the stripline’s center conductor connected directly to the patch. The patch receives energy from the feed, which we can couple in many ways. While a microstrip antenna has been around since the 1950s, they only started gaining serious attention in the past two decades.
A microstrip antenna is commonly helpful for a variety of applications. They are low-profile, low-cost, and have good conformability. In addition, they are also easy to manufacture. We can combine the microstrip patch with coaxial probes or microstrip feeding. Other types of feeding include multilayer schemes.
The main difference between microstrip patch antennas and another microstrip antenna is that they are narrow-band and have low gain. This is due to the presence of fringing fields around the antennas. In addition, a microstrip patch antenna’s side view reveals that its current is zero at the feed end and is high at the center.
Polymer flexible-skin contact antenna
A polymer flexible-skin contact antenna (PFSC) is a device with the characteristics of a contact antenna and skin flexibility. This type of device is useful for sensing biopotentials and communication. In this type of antenna, we deposit the conductive material layer over the base substrate 213, which allows the antenna to stretch.
We can manufacture the PFSC in many different ways. In one method, we laminate a polymer thin film over an electrode. Then, we deposit a thin layer of metal on the adhesive—the substrates helpful in this process range in thickness from a few millimeters to several microns.
Another approach is to apply a serpentine mesh pattern to the flexible antenna. The mesh pattern can increase the PFSC’s stretchability.
Near field communication tags
We can create a microstrip antenna for Near Field Communication (NFC) by creating an antenna consisting of two separate patches. A layer of foam separates these patches. Various degrees of freedom are available to the designer when constructing the patch antenna, including the relative permittivity of the patches and the height of the foam. One of the main advantages of using a microstrip antenna is that they do not require a microstrip transmission line and can conform to the skin.
Near-field antennas are ideal for use in applications that require a consistent read zone. They can detect tags at a distance but are not always suitable for indoor environments. In addition, near-field antennas can read tags at shorter distances than far-field antennas, which are polarization-independent when we place the tags close to the antenna surface.
The cost of NFC tags depends on the memory capacity of the microchip and the number of data points the antenna collects. Therefore, the lowest transmission power is necessary for the tag to be effective, and the antenna must be as close to the microchip’s series resistance as possible. The microchip is typically made with a silver-coated conductive thread to minimize the amount of power dissipated by the antenna. This material has a lower resistivity, so it is preferred.
Microstrip Patch Antenna Calculator
When designing a Microstrip Patch Antenna, there are several factors you must consider. First, input impedance affects the amount of radiation that reaches the patch. We can measure the input impedance between the patch’s center and edge.
Effective dielectric constant (EDC) is a factor that controls the resonance of a Microstrip Patch Antenna. You can find this out using a Microstrip Calculator. One can also calculate the antenna’s half-wavelength by knowing the substrate’s ER and the air’s ER. You can also increase the bandwidth by adding a second patch.
Microstrip Patch Antenna Calculators help determine the length and width of rectangular Microstrip Patch Antennas. The calculator also allows you to input the width and height of the substrate. These variables are necessary for calculating the length and width of the antenna.
Another critical parameter is the feed point. Antennas should have similar polarization for optimal performance. You can use the Microstrip Patch Antenna Calculator to determine the best possible antenna for your application. The calculator will generate all three polarizations for you.
We can find RF Calculators on Google Play. To install the app, search for RF Calculators and tap the Install button. The application will request some permissions. After accepting them, the app will start the installation process. A confirmation message will be displayed once the installation is complete.
Simulation and Measurement of Patch Antenna in Free Space
This article focuses on the simulation and measurement of a patch antenna in free space. In addition, it describes the proposed MTM 3X4 array and S-shaped metamaterial. These metamaterials can help create a patch antenna that efficiently receives and distributes electromagnetic radiation. The main challenge with such an antenna is achieving high radiation efficiency.
Simulation of patch antenna
A patch antenna simulation is a valuable tool for analyzing the characteristics of an antenna. First, the desired patch antenna design is entered in a CST in the simulation, and we compute its properties. Then, the desired directivity pattern is computed by relating the fields in the slots to the equivalent current density. We can do this using the radiation equation, with the ground plane being infinite and the substrate truncated at the patch’s edge.
A four-row aperture structure is designed, processed, and tested in the simulation. The patch is fed either from its edge or the center, and the antenna’s impedance will be higher or lower depending on the direction of feeding. The optimum feed point lies between the center and the edge. A 50 O SMA connector is helpful for back-feed at D1 from the patch’s center.
The simulated results also include the effect of the metamaterial’s orientation on the patch antenna’s gain. As the metamaterial is anisotropic, its centers parallel the H and E-field directions. The distance between the metamaterials is approximately 2 mm.
Measurement of patch antenna in free space
Measuring a microstrip antenna in free space is an essential part of biomedical research. Depending on their size, the microstrip antenna can detect pathological samples. These tests require accurate electrical measurements, and the data generated can be helpful for various purposes.
The fringinging fields around the antenna cause the radiation emitted by a patch antenna. The two fringing E-fields on the antenna’s surface area in the +y direction add together in phase to produce radiation. An equal current then cancels this radiation in the ground plane.
The radiation patterns of the proposed antenna were measured, simulated, and photographed. The antenna is made of copper and is coated with tin to prevent oxidation. The peak gain is 4.95 dB at 3.95 GHz and 4.88 dB at 2.95 GHz, respectively.
Measurement of patch antenna with proposed MTM 3X4 array
Measurement of patch antenna with proposed MTM 3-X4 array: The proposed MTM 3X4 array can produce higher bandwidth, directivity, and lower VSWR. Its performance can be evaluated through numerical simulations using HFSS software. The simulated return loss, S11, is smaller than 2. VSWR and bandwidth are 3.92 THz.
The proposed MTM 3X4 array has been ideal for a 94GHz radar application. We feed the antenna with a microstrip feedline whose input impedance is 50O. The length and width of the quarter wave transformers help calculate the antenna’s input impedance. The results compare to those obtained with CST software.
The proposed antenna comprises a modified meander line patch and a partial ground plane. In addition, we incorporate an NZI metamaterial layer under the antenna. The metamaterial structure consists of metallic arms and a split ring resonant (SRR) structure.
Measurement of patch antenna with proposed S-shaped metamaterial
Various optimization techniques have helped improve the properties of a microstrip antenna. One such technique is the introduction of the metamaterial. We achieve this by incorporating periodic structures with parameters smaller than the wavelength of the incoming electromagnetic wave. As a result, we modify the behavior of the metamaterial. This technique fabricates novel antenna structures with improved performance parameters and miniaturization.
The proposed metamaterial superstrate can suppress surface waves. This property helps the metamaterial antenna reduce its reflection coefficient significantly. This metamaterial structure provides better directivity and reduces the mutual coupling effect. The microstrip transmission line has a higher gain than the conventional a microstrip antenna.
This antenna incorporates a two-segment SRR Labyrinth metamaterial into its substrate. As a result, the antenna’s bandwidth is 600% wider, and the VSWR improves by 1%. The antenna is also 400% smaller than the conventional version.
