Description:Field of Invention
The present invention relates to designing and integrating an AMC (Artificial magnetic conductor) to enhance the gain of an ordinary microstrip patch antenna. In detail a microstrip patch antenna is backed with an AMC to decrease the radiation loss caused due to back lobes and enhance the overall gain of the antenna.

The objectives of this invention
The objective of this invention is to increase the gain of the antenna by nullifying the radiation loss caused due to back lobe using AMC.

Background of the invention
In our invention, a novel artificial magnetic conductor (AMC) combined with a straightforward broad band antenna is developed for wireless body area network (WBAN) applications. A 50 Ohm microstrip line provides feeding to the flexible substrate where a semicircular patch is incorporated into the antenna design. With 10dB return loss band-width from 8GHz to 15GHz, this antenna shows a broad band. A novel AMC surface is developed that precisely mimics the top antenna patch by using a planar array of semi-circular patches as unit cells to limit the backward scattering wave towards the human body. The suggested AMC integrated antenna's Specific Absorption Rate (SAR) is equivalent to that of other PEC and conventional AMC integrated antennas (with square unit cell), according to simulation results. The comparison above shows that the suggested antenna, which has improved from -2.1 dB to 1.84 dB, achieves the best realized gain at phi=0°. The suggested AMC integrated flexible antenna is a viable contender for WBAN applications because of its lower SAR value and gain increase. (T. M. Das, et al., 2019).
A flexible patch antenna with high gain that uses metasurface in place of a backed ground plane. On the flexible ROGERS 3003 substrate, the four equal meta surfaces are positioned. Two hexagonal gaps on a metal sheet make up the meta surface. For the meta surface, a third metal gap has also been formed. This paper also examines the impact of increasing the number of meta surface planes on the change of resonant frequency and impedance bandwidth. With a resonance frequency of 11.4GHz, the maximum impedance bandwidth of 5.94% (10.93GHz to 11.6GHz) is achieved. With a gain of 19.7 dB, this is an extremely high gain that might be utilized for satellite communications (A. B. Dey and W. Arif., et al., 2019).
Then, with better performance, a single square-shaped AMC layer is utilized in place of the metal ground. The 90° AMC reflection phase is used for the lower mode (at 1.38 GHz) in order to modify the electromagnetic field distribution and produce monopole-like unidirectional linear polarization (LP) radiation. In the meantime, the AMC with a 0° reflection phase is thought to function as a reflector to provide patch-like unidirectional circular polarization (CP) radiation for the upper mode (at 1.57 GHz). (J. Lin, Z. Qian., et al., 2017).
Detailed of Prior Art
A slot antenna consists of the following components: a waveguide member that is positioned between the first and second electrically conductive members, with an electrically conductive waveguide face shaped like a stripe opposing the first electrically conductive surface and the waveguide member extending in a first direction along the first electrically conductive surface; a second electrically conductive member that is positioned opposite the first electrically conductive surface; and an artificial magnetic conductor that extends on both sides of the waveguide member, situated between the first electrically conductive member and the second electrically conductive member. There are one or more slots in the first electrically conducting member.A complicated slot comprises at least one slot, which is composed of two vertical portions and a lateral piece connecting the two vertical portions. The complicated slot's lateral section crosses the first direction and is oriented in opposition to the waveguide face. (US10236591B2)
The components of a slot array antenna are as follows: a waveguide member with an electrically conductive waveguide face that extends along the first direction in opposition to the slots; an artificial magnetic conductor that extends on both sides of the waveguide member; and an electrically conductive member with an electrically conductive surface and slots within, the slots being arrayed in a first direction along the conductive surface. In order to increase the distance between the conductive surface and the waveguide face in relation to any nearby sites, at least one of the conductive members and the waveguide member has dents on the conductive surface and/or the waveguide face. The first, second, and third dents are among the dents; they are next to one another and follow the initial direction in succession. The separation between the first and second dent centers is not the same as the separation between the second and third dent centers.(US10439298B2)
Microwave technology includes a unique circular polarization millimeter wave broadband planar reflection array antenna with a positive feed excitation multi-frequency point. The micro-strip n x n petal reflection array is made up of n x n single-layer tightly-coupled petal units that meet the recursion relation, are uniformly arranged on the upper surface of the medium substrate, are in rotary distribution at a specific angle, and face the feed source. The micro-strip n x n petal reflection array is composed of a dielectric substrate, a grounding plate, a feed source, and a micro-strip n x n petal reflection array; A grounding plate with a rectangular shape is located on the back of the dielectric substrate. Each close-coupled petal unit is made up of two million equal-sized regular polygon open resonance rings that surround regular two million polygonal gaps. The regular polygon open resonance rings of varying sizes each function at a different frequency to form a multi-resonance unit. The millimeter wave antenna has good radiation performance, is easy to implement in engineering, has a basic structure, is affordable, and can operate in various millimeter wave bands. It also has a 5G standard.( CN112467399A)

Summary of Invention
This patent discusses about the usage of an AMC (Artificial magnetic conductor) to improve the parameters of a compact microstrip patch antenna like radiation properties, efficiency, gain. By mimicking the properties of a perfect magnetic conductor and controlling the electromagnetic fields around the antenna.
Detailed description of the invention
Previous works of AMC integration with antennas have produced variety of results for various frequencies, increase in gain and other parameters. This patent showcases millimeter wave frequency i.e. 30-300GHz. The design of the AMC is made out of a square cut out which looks like a frame and inside the frame there is another square in which semicircles of equal radius are cut out from each side of the square. The reflection co efficient of the AMC is around 29GHz. Which is the main parameter to be considered while designing an AMC. The substrate used for AMC design is Fr4 and the radiating material is copper.
Over the years, a number of scholars have put forth analytical techniques for describing the distinct AMC characteristics, such as incident plane wave in-phase reflection. The techniques used for analysis pertain to simulating the electromagnetic characteristics of those structures and their interaction. Usually, an elementary structure is iterated in a specific sequence to create these structures. The unitelement (UE) or unit-cell is the recognized term for the elementary structure, which outlines the fundamental characteristics of the artificial structure. These artificial magnetic conductors, or AMCs, are modeled and examined in any simulator by use of unit-cell-applied periodic boundary conditions. It is anticipated that an infinite array of unit-cells oriented in the direction of the lattice vectors will design the metamaterial. S-parameter retrieval techniques can be used to evaluate electromagnetic properties like permittivity (e) and permeability (µ).
The application of AMC technology for printed antennas has received a lot of attention over the past 25 years. AMC structures' intriguing qualities have given rise to a variety of antenna applications. In order to prevent out-of-phase reflection and surface wave propagation, AMC structures are thought to be a superior alternative. AMC structures have been used by common radiating structures, such as basic patch antennas, dipole antennas, slot antennas, monopole antennas, fractal antennas, etc., to improve performance. The antenna's gain has been increased thanks to the AMC structures described in. In a wireless body area network, the wearable antenna is crucial (WBAN).
These days, patients can have the gadgets implanted in them or worn on them to monitor different aspects of their physiology and surrounding environment. The antenna must be resized for wearable applications and installed on a variety of curved surfaces. Therefore, it is essential to examine the antenna's electromagnetic behavior when bent. Artificial magnetic conductors can be either pass or stop bands, depending on what the communication system needs. High impedance surfaces (HIS), for example, are actually excellent prospective metasurface structures for antenna applications. The two intriguing characteristics that these surfaces display are One is the Electromagnetic Band Gap (EBG), which can prevent surface wave propagation, so minimizing mutual interference, for example, between various radiating antennas or arrays of antennas. The second one causes the meta surface to behave similarly to an artificial magnetic conductor (AMC) by reflecting incident waves in-phase. By serving as an electromagnetic wave reflector, this second crucial feature enables the placement of such a met surf in close proximity to an antenna, hence improving its directivity.This letter presents a low-profile dual-band, dual-mode, dual-polarized (DBDMDP) antenna based on artificial magnetic conductor (AMC). One reference antenna was initially accomplished with dual-band dual-polarized property but high back radiation. It was composed of two double-printed crossing dipoles using unoccupied quarter-rings.This letter presents a low-profile dual-band, dual-mode, dual-polarized (DBDMDP) antenna based on artificial magnetic conductor (AMC). One reference antenna was initially accomplished with dual-band dual-polarized property but high back radiation. It was composed of two double-printed crossing dipoles using unoccupied quarter-rings.
The design of a suitable antenna which utilizes the AMC and improves the parameters is a microstrip patch antenna with two U shaped cuts on each side of the square which operates on two different frequencies 31.5 GHz and 38 GHz. Only one AMC is not sufficient enough to support the antenna hence an 4x4 AMC array is designed with equal spacing from each other and places beneath the antenna from a distance of ?/4. The antenna acts as a floquet port to the AMC providing electromagnetic waves which emit from the back lobes. The initial gain of the microstrip patch antenna without AMC backing is 4.4dB after successful integration of the AMC array with the antenna the overall gain has improved to 6.4dB which is a significant improvement. The final operating frequency of the antenna with AMC array is 39GHz.

Brief description of Drawing
Figure 1: This image the gain of the microstrip patch antenna without any AMC backing is around 4.4dbi Which is an ordinary operating gain for a microstrip patch antenna operating at 39GHz. This figure represents the AMC in a 6x6 array arranged at 0.5mm spacing between each other on a fr4 substrate with a ground the port to the AMC array is given by the antenna which is placed at lambda/4 distance from the antenna. The reflected waves from the back lobe of the antenna are reflected on the AMC which are reflected again so that all the waves go front.
Figure 2: Reflection coefficient of an AMC is the factor which is the factor considered. Here the reflection coefficient of the AMC at 0 degrees is the frequency at which it operates and the bandwidth is from-90 to 90.The image shown the reflection coefficient of AMC unit cell is shown which is 28.9 GHz and the bandwidth is ranging from 28.6 GHz to 29.5 GHz. In the image the s11 parameter of the microstrip patch antenna is shown it operates at 32.4GHz and 38.4GHz.
Figure 3: The image shows the radiation pattern of the microstrip patch antenna along with the gain which is 4.4dB.
Figure 4: The image shows the 2D radiation pattern of the AMC backed antenna. The final gain of the antenna is 6.4dB. Which is 2dB increase from the initial gain , Claims:The scope of the invention is defined by the following claims,
Claims:
1. A method for feeding a patch antenna, comprising:
a) The proposed antenna design incorporates a compact and low-profile planar structure, suitable for integration into modern communication devices.
b) The AMC backing provides a tailored reflection phase, effectively mitigating the inherent ground plane limitations at mm Wave frequencies.
c) The coupling energy from the parasitic element to the patch antenna is passed through electromagnetic fields.
2. As per claim 1, antenna represents the AMC in a 6x6 array arranged at 0.5mm spacing between each other on a FR4 substrate with a ground the port to the AMC array is given by the antenna which is placed at lambda/4 distance from the antenna. The reflected waves from the back lobe of the antenna are reflected on the AMC which are reflected again so that all the waves go front.
3. As per claim 1, antenna without any AMC backing operates around 38GHz and has a gain of4.4db. Due to high back lobes for any antenna integrating it with an AMC provided us with no back loses.
4. As per claim 1, the gain pf the antenna improved significantly up to 6.4db. Furthermore after testing the fabricated prototype the antenna integrated with AMC showed 6.0db gain and37GHz frequency which is ideal for millimeter wave applications.