A microstrip patch antenna

Abstract

A microstrip patch antenna (300) is disclosed. The microstrip patch antenna (300) includes a ground plane, a dielectric substrate disposed on the ground plane, a radiating patch disposed on the dielectric substrate, and a feed element connected to the central width axis of the radiating patch. The feed element is configured to excite the radiating patch. The microstrip patch antenna (300) further includes a plurality of shorting pins electrically connecting the radiating patch to the ground plane. Each of the plurality of shorting pins being positioned at a predetermined location relative to the patch to modify the radiation pattern, thereby forming a radiation null in a back lobe of the antenna’s far-field pattern.

Description

TECHNICAL FIELD

[0001] The present disclosure generally relates to wireless communication and moreparticularly relates to a microstrip patch antenna forming a radiation null in a back lobe ofantenna's far-field pattern.BACKGROUND

[0002] In the evolving landscape of wireless communication technologies, microstrip patchantennas have gained prominence due to their compact size, ease of fabrication, andcompatibility with integrated circuits. These antennas are widely used in mobile devices,wearable electronics, and other compact wireless systems where space and weight constraintsare critical. Their planar structure and low-profile design make them particularly attractive forapplications requiring embedded or surface-mounted antenna solutions.

[0003] Despite these advantages, conventional microstrip patch antennas tend to producenoticeable back radiation. This backward emission of electromagnetic energy not only reducesthe overall radiation efficiency and directivity of the antenna but also poses potential healthconcerns for users, especially in close-proximity applications such as smartphones, smartwatches, and other body-worn devices. The undesired back radiation can lead to increasedelectromagnetic exposure to the user and may interfere with nearby electronic components,thereby compromising system performance and safety.

[0004] Moreover, existing solutions fail to provide a compact and passive approach thatenables analytical control over the creation of a directional null in the backward radiation lobe.Conventional techniques often rely on complex active circuitry, lossy materials, or structuralmodifications that compromise forward gain and overall antenna efficiency. As a result, theseapproaches are unsuitable for applications requiring low-profile, high-performance antennasthat minimize Specific Absorption Rate (SAR) without introducing additional losses or designcomplexity.

[0005] To address these limitations, there is a growing need for antenna designs that minimizeback radiation while maintaining the desirable characteristics of microstrip patch antennas.SUMMARY

[0006] This summary is provided to introduce a selection of example inventive concepts, in asimplified format, that are further described in the detailed description of the presentdisclosure. This summary is neither intended to identify key or essential inventive concepts ofthe disclosure nor is it intended to limit the scope of the disclosure.

[0007] The present disclosure provides a shorting-pin-loaded rectangular microstrip patchantenna, designed for mobile and wearable environments, where close proximity to the humanbody creates challenges related to back radiation and Specific Absorption Rate (SAR).

[0008] According to example embodiments of the present disclosure, a microstrip patchantenna is disclosed. The microstrip patch antenna includes a ground plane, a dielectricsubstrate disposed on the ground plane, a radiating patch disposed on the dielectric substrate,and a feed element connected to the central width axis of the radiating patch. The feed elementis configured to excite the radiating patch. The microstrip patch antenna further includes aplurality of shorting pins electrically connecting the radiating patch to the ground plane. Eachof the plurality of shorting pins being positioned at a predetermined location relative to thepatch to modify the radiation pattern, thereby forming a radiation null in a back lobe of theantenna's far-field pattern.

[0009] Features and advantages of the microstrip patch antenna according to various exampleembodiments disclosed herein may be further understood with reference to the appendeddrawings. It is appreciated that these drawings do not depict all possible example embodimentsof the invention, and are therefore not to be considered as limiting the scope of the appendedclaims.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] These and other features, aspects, and advantages of the present disclosure will becomebetter understood when the following detailed description is read with reference to theaccompanying drawings in which like characters represent like parts throughout the drawings,wherein:

[0011] Figure 1 illustrates an example environment of a user device with a microstrip patchantenna;

[0012] Figure 2 illustrates a radiation pattern of a conventional microstrip patch antenna;

[0013] Figure 3 illustrates a microstrip patch antenna, according to an embodiment of thepresent disclosure;

[0014] Figures 4A-4D illustrate various views of the microstrip patch antenna, according toan embodiment of the present disclosure;

[0015] Figures 5A-5B illustrate (i) the influence of feed position on the performanceparameters of a conventional microstrip patch antenna, along with associated simulationdetails, and (ii) a single-pin loaded microstrip patch antenna employing a coaxial feedarrangement, according to an embodiment of the present disclosure;

[0016] Figures 6A-6B illustrate a comparative analysis between the simulated radiationpattern of a conventional microstrip patch antenna and that of the proposed shorted microstrippatch antenna, according to an embodiment of the present disclosure;

[0017] Figures 7A-7B illustrate tabular representations of simulated radiation characteristicsof the proposed design across multiple operating frequencies, according to an embodiment ofthe present disclosure;

[0018] Figure 8 illustrates a tabular representation of simulated radiation characteristicscorresponding to different patch geometries, according to an embodiment of the presentdisclosure; and

[0019] Figure 9 illustrates a sequence flow diagram detailing the operational aspects of themicrostrip patch antenna, according to an embodiment of the present disclosure.

[0020] Skilled artisans will appreciate that elements in the drawings are illustrated forsimplicity and may not have necessarily been drawn to scale. For example, the flow chartsillustrate the method in terms of the most prominent steps involved to help improveunderstanding of aspects of the present disclosure. Furthermore, in terms of the constructionof the device, one or more components of the device may have been represented in thedrawings by conventional symbols, and the drawings may show only those specific details thatare pertinent to understanding the example embodiments of the present disclosure so as not toobscure the drawings with details that will be readily apparent to those of ordinary skill in theart having the benefit of the description herein.DETAILED DESCRIPTION

[0021] For the purpose of promoting an understanding of the principles of the disclosure,reference will now be made to the various example embodiments, and specific language willbe used to describe the same. It will nevertheless be understood that no limitation of the scopeof the disclosure is thereby intended. Alterations and further modifications to variousillustrated example embodiments, and such further applications of the principles of thedisclosure as illustrated therein, may be made by one skilled in the art.

[0022] It will be understood by those skilled in the art that the foregoing general descriptionand the following detailed description are explanatory of the invention and are not intended tobe restrictive thereof.

[0023] Reference throughout this specification to "an aspect", "another aspect" or similarlanguage means that a particular feature, structure, or characteristic described in connectionwith an example embodiment may be included in at least one example embodiment of thepresent invention. Thus, appearances of the phrase "in an example embodiment", "in anotherexample embodiment", and similar language throughout this specification may, but do notnecessarily, all refer to the same example embodiment.

[0024] The terms "comprises", "comprising", or any other variations thereof, are intended tocover non-exclusive elements, such that a process or method that comprises a list of steps mayinclude other steps not expressly listed in such a process or method. Similarly, one or moredevices or sub-systems or elements or structures or components proceeded by "comprises... a"does not, without more constraints, preclude the existence of other devices, other sub-systems,other elements, other structures, other components, additional devices, additional sub-systems,additional elements, additional structures, or additional components.

[0025] As is traditional in the field, example embodiments may be described and illustrated interms of blocks that carry out a described function or functions. These blocks, which may bereferred to herein as units, modules, the like, may be physically implemented by analog ordigital circuits such as logic gates, integrated circuits, microprocessors, microcontrollers,memory circuits, passive electronic components, active electronic components, opticalcomponents, hardwired circuits, or the like, and may optionally be driven by firmware and / orsoftware. The circuits may, for example, be embodied in one or more semiconductor chips, oron substrate supports such as printed circuit boards or the like. The circuits constituting a blockmay be implemented by dedicated hardware, or by a processor (e.g., one or more programmedmicroprocessors and associated circuitry), or by a combination of dedicated hardware toperform some functions of the block, and a processor to perform other functions of the block.Each block may be physically separated into two or more interacting and discrete blockswithout departing from the scope of the invention. Likewise, the blocks may be physicallycombined into more complex blocks without departing from the scope of the disclosure.

[0026] Figure 1 illustrates an example environment 100 that includes a user device 102. Theenvironment 100 represents a typical usage scenario where the user device 102 is positionedadjacent to the head of a user during operation. In the illustrative embodiment, the user device102 corresponds to a mobile device, such as a smartphone, configured for wirelesscommunication. However, the user device 102 may alternatively be any suitable wearabledevice, including but not limited to smartwatches, fitness trackers, or augmented realityheadsets, without departing from the scope of the present disclosure.

[0027] The user device 102 may be integrated with a microstrip patch antenna (not shown inFigure 1) that enables transmission and reception of radio frequency (RF) signals forcommunication with external networks or devices. The microstrip patch antenna is typicallyimplemented as a planar structure mounted on or embedded within a printed circuit board(PCB) of the user device 102. This antenna design is widely adopted due to its low profile,lightweight construction, and ease of integration with compact electronic systems, making itsuitable for mobile and wearable applications.

[0028] In the context of the mobile device embodiment, the microstrip patch antenna facilitateswireless connectivity for cellular communication, Bluetooth, Wi-Fi, and other short-range orlong-range communication protocols. The microstrip patch antenna operates by radiatingelectromagnetic energy into free space and receiving incoming signals from correspondingcommunication nodes. The planar configuration of the microstrip patch antenna allowsefficient coupling with RF circuitry while maintaining the overall compactness of the userdevice 102.

[0029] However, conventional microstrip patch antennas exhibit a notable disadvantage insuch environments. Specifically, these antennas tend to produce significant back radiationtoward the rear side of the antenna structure, which in the illustrated scenario corresponds tothe side facing the user's head. This back radiation not only reduces the forward gain andoverall efficiency of the antenna but also results in increased electromagnetic exposure to theuser. Such exposure is undesirable in close-proximity applications, as it may raise safetyconcerns and interfere with sensitive electronic components within the user device 102.Therefore, reducing back radiation while preserving the performance benefits of microstrippatch antennas remains a critical design challenge addressed by the present disclosure.

[0030] Figure 2 illustrates a radiation pattern 204 of a conventional microstrip patch antenna202. The radiation characteristics of the microstrip patch antenna 202 are primarily governedby the distribution of surface currents on the radiating patch and the boundary conditionsimposed by its geometry and feeding configuration. In a typical design, a radiating patchoperates as a resonant cavity, where fringing fields at the edges contribute to radiation. Thisconfiguration results in a bidirectional radiation pattern 204, with significant energy radiatedin both the forward direction 204a and the backward direction 204b.

[0031] In conventional patch antenna implementations, back radiation is primarily generatedby secondary mechanisms such as ground-plane edge diffraction, surface-wave leakage, andsubstrate-supported modes. These effects allow a portion of the radiated energy to propagatetoward the rear of the antenna, producing measurable radiation in the backward direction 204bat θ = 180°. At θ = 180° (backward radiation direction), the radiation characteristics of boththe E-plane and H-plane exhibit finite, nonzero values, demonstrating the inherent backwardradiation of a rectangular patch antenna. This backward emission is undesirable in applicationswhere the microstrip patch antenna 202 is positioned close to the human body, such as inmobile devices or wearable electronics. High back radiation not only reduces the effectiveforward gain and overall antenna efficiency but also increases electromagnetic exposure to theuser, which is quantified by the Specific Absorption Rate (SAR). Elevated SAR values are acritical concern in regulatory compliance and user safety.

[0032] The radiation pattern 204 shown in Figure 2 exemplifies the inherent limitation ofconventional microstrip patch antennas. The pattern demonstrates the need for structuralinnovations that control current flow and optimize radiation characteristics for modern wirelessapplications, where compactness, efficiency, and user safety are paramount.

[0033] Accordingly, to mitigate this drawback, the present disclosure provides designmodifications such as introducing shorting pins at carefully selected positions on the microstrippatch antenna 202. These shorting pins alter the surface current distribution and introducephase shifts that result in destructive interference in the backward direction 204b. Bysuppressing radiation toward θ = 180°, the antenna achieves a more directional pattern,favoring the forward direction 204a. This mechanism may significantly reduce back radiationand, consequently, lower SAR when the antenna operates in proximity to the human body.

[0034] Figure 3 illustrates a microstrip patch antenna 300 (may be interchangeably referred toas the antenna 300), according to an embodiment of the present disclosure. The microstrippatch antenna 300 includes a ground plane 302, a dielectric substrate 304 disposed on theground plane 302, and a radiating patch 306 positioned on the dielectric substrate 304. Theantenna 300 may also include a plurality of shorting pins 310 positioned at a predeterminedlocation relative to the radiating patch 306 to modify the radiation pattern. In one embodiment,the ground plane 302 may be formed of a conductive material such as copper, aluminum, orany suitable metal layer. The ground plane 302 provides a stable reference for the antenna andminimizes undesired radiation toward the rear side of the antenna structure. The ground plane302 may be rectangular in shape, corresponding to the geometry of the radiating patch 306 andthe dielectric substrate 304. The rectangular configuration may be commonly used for ease offabrication and predictable electromagnetic performance.

[0035] In an alternative embodiment, the patch 306 may have any suitable shape based ondesign requirements of the microstrip patch antenna 300. For example, the patch 306 may besquare, circular, elliptical, or irregular in shape to accommodate specific device form factorsor to optimize antenna performance for multi-band or wideband operation. The dimensionsand shape of the patch 306 may be selected to control impedance, bandwidth, and radiationcharacteristics while maintaining structural integrity and compactness.

[0036] In an embodiment, the ground plane 302 may also serve as an electrical termination fora plurality of shorting pins 310, which connect the radiating patch 306 to the ground plane 302.This configuration modifies the surface current distribution on the radiating patch 306,suppressing back radiation and improving forward gain. The ground plane 302, in combinationwith the dielectric substrate 304 and radiating patch 306, forms the layered structure thatdefines the electromagnetic behavior of the antenna 300.

[0037] In one embodiment, the dielectric substrate 304 is disposed on the ground plane 302and provides mechanical support for the radiating patch 306 while influencing theelectromagnetic characteristics of the microstrip patch antenna 300. The dielectric substrate304 determines key parameters such as impedance, bandwidth, and radiation efficiency. Thematerial of the dielectric substrate 304 may include low-loss substrates such as FR4, RogersRT / Duroid, or any suitable dielectric material having a predetermined relative permittivity andthickness to achieve the desired antenna performance.

[0038] The dielectric substrate 304 serves as an insulating layer between the radiating patch306 and the ground plane 302, enabling the formation of a resonant cavity that facilitatesradiation. The thickness and dielectric constant of the substrate 304 are selected to optimizethe operating frequency and minimize surface wave propagation. In one or more embodiments,the dielectric substrate 304 may include additional features such as electromagnetic bandgap(EBG) structures or artificial magnetic conductors to further enhance isolation and reduce backradiation.

[0039] In an embodiment, the dielectric substrate 304 comprises a plurality of vias configuredto accommodate the plurality of shorting pins 310. These vias extend through the dielectricsubstrate 304 and provide precise alignment and electrical connectivity between the radiatingpatch 306 and the ground plane 302. The shorting pins 310 inserted into these vias modify thesurface current distribution on the radiating patch 306, introducing controlled phase shifts thatresult in destructive interference in the backward radiation direction. This configurationsuppresses back radiation and improves forward gain, thereby reducing the SAR when theantenna 300 operates in proximity to the human body.

[0040] In an alternative embodiment, the dielectric substrate 304 may be implemented as amultilayer structure to support additional functionalities such as impedance matching networksor integrated filters. The vias may be plated or filled with conductive material to ensure low-resistance connections for the shorting pins 310. The substrate 304 may also include cavitiesor recesses to accommodate feed elements or additional components without increasing theoverall profile of the antenna 300.

[0041] In one embodiment, the radiating patch 306 is a planar conductive element disposed onthe dielectric substrate 304. The radiating patch 306 is configured to emit and receiveelectromagnetic waves when excited by the feed element 308 (e.g., a coaxial feed). Thegeometry of the radiating patch 306, including its length, width, and shape, governs theresonant frequency, impedance characteristics, and radiation pattern of the microstrip patchantenna 300. The radiating patch 306 may be formed of a conductive material such as copper,aluminum, or any suitable metal layer deposited on the dielectric substrate 304.

[0042] The planar nature of the radiating patch 306 enables a low-profile antenna designsuitable for integration into compact electronic devices such as mobile phones, wearabledevices, and IoT modules. The dimensions of the radiating patch 306 are typically selectedbased on the operating wavelength and dielectric properties of the substrate 304 to achieveresonance at a desired frequency band.

[0043] In an alternative embodiment, the radiating patch 306 may include additional structuralfeatures such as slots, notches, or apertures to support multi-band operation, polarizationdiversity, or bandwidth enhancement. The shape of the radiating patch 306 may be rectangular,square, circular, or any suitable geometry depending on design requirements. For example, arectangular patch may be used for single-band operation, while a slotted patch may enabledual-band or wideband performance.

[0044] In another embodiment, the radiating patch 306 may be configured with the integratedshorting pins 310 positioned at predetermined locations to modify the surface currentdistribution. These shorting pins 310 introduce controlled phase shifts that suppress backradiation and improve forward gain. The radiating patch 306 may also include vias orconductive extensions to accommodate these shorting pins and ensure reliable electricalconnectivity with the ground plane 302.

[0045] The radiating patch 306, in combination with the dielectric substrate 304 and groundplane 302, forms the resonant cavity that determines the antenna's electromagnetic behavior.The feed element 308 provides excitation to the radiating patch 306, enabling efficient couplingwith RF circuitry. The planar configuration of the radiating patch 306 ensures ease offabrication and integration into printed circuit boards or device housings without increasingoverall thickness.

[0046] In one embodiment, the feed element 308 is configured to provide electrical excitationto the radiating patch 306 for transmitting and receiving electromagnetic signals. The feedelement 308 establishes an interface between the radiating patch 306 and associated radiofrequency (RF) circuitry, enabling efficient coupling and impedance matching. The feedelement 308 may be implemented as the coaxial feed 308, wherein the inner conductor passesthrough the dielectric substrate 304 and is connected to the radiating patch 306, while the outerconductor is connected to the ground plane 302.

[0047] The position and orientation of the feed element 308 may be selected to achieve optimalimpedance matching and minimize reflection losses. The feed element 308 is preferablypositioned along, or slightly offset from, the center line of the radiating patch 306, the preciselocation being selected to achieve the desired polarization purity and bandwidth performance.As illustrated in Fig. 5A (second row), placement of the feed along the width center line of thepatch (Where W>L) results in a higher front-to-back ratio and lower back radiation comparedto other feed-pin configurations. The dimensions of the feed element 308 are determined basedon the operating frequency and substrate properties to ensure efficient power transfer.

[0048] The feed element 308 may be implemented as a coaxial probe, or any suitable feedingtechnique, enabling efficient coupling between the radiating patch 306 and associated radiofrequency circuitry.

[0049] The plurality of shorting pins 310 may extend between the radiating patch 306 and theground plane 302 through the dielectric substrate 304. The shorting pins 310 may bestrategically positioned to modify the surface current distribution on the radiating patch 306.This configuration introduces controlled phase shifts that result in destructive interference inthe backward radiation direction, thereby suppressing back radiation and improving forwardgain. Such suppression of back radiation directly contributes to reducing the SAR when theantenna 300 operates in proximity to the human body, enhancing user safety withoutcompromising antenna performance.

[0050] Physically, the plurality of shorting pins 310 modifies the surface current paths andintroduces phase shifts across the patch. When combined with the excitation from the feed atthe selected location (i.e., along the center line of the patch), these altered currents lead todestructive interference in the -Z (θ = 180°) direction, thereby producing a radiation null. Thecorresponding far-field radiation patterns in Figs. 7A, 7B, 8 substantiate this explanation.

[0051] The antenna 300 may be operated based on an analytical model that predicts a net fieldcontribution of each shorting pin 310. By satisfying the condition:(Equation)

[0052] The far-field pattern cancels backward radiation without requiring absorbing layers orelectronic phase control. This approach provides a compact, passive, and analyticallycontrollable solution that retains or enhances forward gain. The design is compatible with low-profile PCB fabrication, making it suitable for mobile and wearable devices.

[0053] The arrangement shown in Figure 3 demonstrates the layered structure and functionalintegration of components within the microstrip patch antenna 300. This embodiment providesa compact, low-profile antenna design suitable for mobile and wearable devices, addressinglimitations of conventional patch antennas while maintaining desirable characteristics such asease of fabrication and low cost.

[0054] Figures 4A-4D illustrate various views of the microstrip patch antenna 300, accordingto an embodiment of the present disclosure. The microstrip patch antenna 300 clearly illustratesthe shorting pins 310 and the corresponding connection with different surfaces of the micropatch antenna. For example, an exploded view of the microstrip patch antenna 300, where alayer-by-layer interconnection between the other components can be seen.

[0055] Figure. 4A illustrates an exploded perspective view of the microstrip patch antenna300 assembly. The microstrip patch antenna 300 comprises the radiating patch 401 (i.e.,radiating patch 306) positioned on the uppermost layer, which serves as the primary radiatingelement for electromagnetic wave transmission. Beneath the radiating patch 401 is thedielectric substrate 402 (i.e., dielectric substrate 304) that provides mechanical support anddetermines the antenna's impedance characteristics. The ground plane 403 (i.e., ground plane302) is disposed below the dielectric substrate 402 to ensure proper isolation and minimizeback radiation. The microstrip patch antenna 300 employs a probe feed 404 (i.e., feed element308) extending through the dielectric substrate 402 and ground plane 403 to deliver theexcitation signal to the radiating patch. Additionally, multiple vias 405 are incorporated toestablish electrical connectivity between layers, thereby enhancing structural integrity andimproving impedance matching.

[0056] Figure. 4B illustrates a cross-sectional view of the microstrip patch antenna 300. Theradiating patch 401 is mounted on the top surface of the substrate 402, which defines theantenna height h and dielectric properties. The ground plane 403 is located at the bottom of thesubstrate (dielectric substrate 402), providing a reference potential for the radiating element.The probe feed 404 penetrates through the substrate (dielectric substrate 402) and ground plane403 to couple the input signal directly to the radiating patch 401. The multiple vias 405 arestrategically distributed within the dielectric substrate 402 to interconnect the radiating patchand ground plane 403, thereby reshaping the surface current distribution to produce destructiveinterference in the -Z direction. This is engineered via and shorting pin arrangementsignificantly improves the front-to-back ratio and suppresses back radiation, resulting in lowerSAR while maintaining stable input impedance and forward-radiation performance. Figure.4C illustrates a top view of the microstrip patch antenna 300. Figure. 4D illustrates a bottomview of the microstrip patch antenna 300.

[0057] Figures 5A-5B illustrate (i) the influence of feed position on the performanceparameters of a conventional microstrip patch antenna, along with associated simulation details500a, and (ii) a single-pin loaded microstrip patch antenna 500b employing a coaxial feedarrangement, according to an embodiment of the present disclosure.

[0058] In the context of the logic for selecting the number and position of shorting pins 310:In mobile, wearable, and body-centric communication systems, microstrip patch antennas arewidely employed; however, such antennas typically exhibit undesirable back radiation, whichdirectly contributes to an increase in Specific Absorption Rate (SAR).

[0059] In one or more exemplary embodiments, to mitigate this drawback, the presentdisclosure provides a rectangular microstrip patch antenna (i.e., microstrip patch antenna 300)incorporating a strategically determined arrangement of feed and shorting pins 310. Thisconfiguration passively suppresses back radiation and establishes a radiation null at an angularposition of θ = 180°. The placement of the feed and shorting pins 310 is not arbitrary; rather,it is derived from an analysis of modal current interactions to achieve destructive interferencein the backward direction while preserving broad forward radiation coverage.

[0060] Feed placement along the width axis: the design initiates with a rectangular patchhaving a width (W) greater than its length (L). A coaxial feed is positioned along the centralaxis of the width. This placement excites the dominant TM10 mode and inherently reduces backradiation due to the symmetrical nature of the excitation. Positioning the feed along this centralline (as illustrated in the second row of Table [Figure. 5A]) enhances the front-to-back ratioand minimizes backward-directed currents compared to off-center feed locations, therebyproviding a baseline improvement in SAR performance. Supporting simulation data ispresented in Table [Figure. 5A].

[0061] Feed locations indicated by dots within the patch exhibit equivalent electromagneticbehavior owing to the structural symmetry of the patch and are therefore consolidated into asingle representation. Simulation results corresponding to various feed positions in themicrostrip patch antenna are summarized in Table [Figure. 5A].

[0062] In one or more exemplary embodiments, for a central shorting pin opposite to the feed,to complement the feed, a single shorting pin is positioned on the center width line directlyopposite to the feed. The top view of the single-pin-loaded shorted patch antenna is shown inthe Figure. 5B. This pin introduces a localized grounding point, forcing the electric field tozero at that location and thereby altering the surface current paths on the patch.

[0063] The induced current in the pin radiates an additional field component that is out ofphase with the backward field of the feed, increasing the front-to-back ratio and reducingresidual back radiation. At θ = 180°, the backward E-plane field is expressed by themathematical equation:EE-plane(180°) = E[Afeed+ Apin,center]

[0064] This equation highlights how the contribution of the central pin partially cancels thefeed's backward radiation, leading to measurable suppression of back lobes. Simulation Detailssubstantiating this are given in the following table, "Comparative analysis of conventional andsingle pin shorted microstrip patch antenna configurations".Table. Comparative performance metrics analysis of three selected antennaconfigurationsTable Computed SAR Values for 10g and I g tissueFor instance, SAR simulations were carried out in CST Studio Suite in accordance with IEEEC95.1-2020 and IEC / IEEE 62209-1. The standard SAM head phantom (1000 x 500 x 200 mm;σ = 1.95 S / m; εr = 52.7), representing a 90th-percentile adult male head, was positioned 1 mmbelow the antenna ground plane during the evaluations.

[0065] In one or more exemplary embodiments, for diagonal shorting pins 310, while thecentral pin reduces back radiation, a deeper null at θ = 180° requires additional cancellationsources. For this purpose, four shorting pins 310 are placed along the diagonals of the patch,located at angular positions such as ±60° and ±120° relative to the feed axis. Each diagonal pinintroduces a secondary current path, radiating additional field components with different phasedelays. At θ = 180°, the total backward field, as expressed by the mathematical equation:Etotal(180°) = (Equation)

[0066] In one or more exemplary embodiments, for the influence of pin position, the positionof each shorting pin is critical in determining the phase of its radiated contribution. A pinplaced opposite the feed along the central axis counteracts the residual backward radiationdirectly. Pins 310 placed along diagonal lines create additional phase-shifted currents thatreinforce this cancellation. By ensuring that the contributions from all pins 310 satisfy thecondition, as expressed by the mathematical equation:Equation

[0067] Where A_n are the complex weighting factors of the radiated fields, a null at θ = 180°can be achieved.

[0068] In one or more exemplary embodiments, for the logic of selecting the number andposition of shorting pins 310, the logic of selecting the number and position of shorting pins310 in this rectangular patch antenna is rooted in achieving destructive interference in thebackward direction. By placing the feed along the central width line, adding a single centralpin opposite to the feed, and reinforcing the cancellation with four diagonal pins 310, theantenna ensures that:EE-plane(180°) ≈ 0 and EH-plane(180°) ≈ 0

[0069] This approach passively engineers a radiation null at θ = 180°, thereby reducing SARwhile maintaining wide forward coverage. The technique provides a unique, low-cost, andanalytically predictable method for radiation pattern shaping, making it highly suitable fornext-generation mobile, wearable, and body-centric wireless systems.

[0070] Figures 6A-6B illustrate a comparative analysis between the simulated radiationpattern of a conventional microstrip patch antenna 600a and that of the proposed shortedmicrostrip patch antenna 600b, according to an embodiment of the present disclosure.

[0071] In a microstrip patch antenna, the radiation characteristics are primarily dictated by thedistribution of surface currents on the patch and the boundary conditions established by itsgeometry and feeding configuration. In a conventional microstrip patch antenna configuration,the radiation characteristics exhibit distinct behavior in the principal planes. Specifically, inthe E-plane (φ = 0°), the radiation pattern demonstrates a non-zero maximum at an angularposition of θ = 180°. Similarly, in the H-plane (φ = 90°), the radiation pattern also attains anon-zero maximum at θ = 180°. These observations are indicative of the inherent symmetryand directional properties of the conventional patch antenna structure, as illustrated in Figure6A ("simulated radiation pattern of conventional microstrip patch antenna").

[0072] In contrast, the present disclosure introduces shorting pins 310 at predeterminedpositions on the patch to alter the surface current distribution such that destructive interferenceoccurs in the backward direction (θ = 180°), as illustrated in Figure 6B. This mechanismeffectively suppresses back radiation and thereby contributes to reducing the SAR when theantenna is deployed in proximity to the human body.

[0073] In one or more exemplary embodiments, for shorting pins 310 as secondary radiators,each shorting pin, implemented as a conductive via between the patch and the ground plane403, imposes a localized short-circuit boundary condition. This constraint forces currents toflow vertically into the ground plane 403, thereby creating an additional radiating element. Inaccordance with antenna theory, any current element influences the overall radiation pattern.Consequently, each shorting pin functions as a secondary radiator, generating electromagneticfields with amplitude and phase characteristics determined by its spatial relationship to the feedpoint and its position on the patch.

[0074] In one or more exemplary embodiments, for superposition and destructive interference,the far-field radiation pattern of the antenna represents the vector summation of contributionsfrom the patch and all shorting pins 310, as expressed by the mathematical equation:Equation

[0075] At θ = 180° (the backward direction), the fields radiated by the shorting pins 310 exhibitspecific phase differences relative to the backward radiation component of the patch. Bypositioning the pins 310 at predetermined angular locations, such as diametrically opposite tothe feed or along diagonal axes, the resulting fields are intentionally configured to be out ofphase with the patch's backward radiation. The superposition of these contributions producesdestructive interference, thereby reducing or nullifying radiation in the backward direction, asdepicted in Fig. B. When diagonal pin positions are selected appropriately, the cumulativecontribution approaches zero, as expressed by the mathematical equation:Equation

[0076] This arrangement ensures destructive interference in the backward direction, resultingin a radiation null in accordance with the principle of superposition governing antennaradiation. A mathematical derivation substantiating this phenomenon is provided below.

[0077] According to the principle of superposition in antenna radiation, according to classicalelectromagnetic theory, the total radiated field of an antenna system is the vector sum of theindividual radiating sources (antenna elements, current segments, or perturbations).In this case:Equation- Equation: amplitude contribution of the nth shorting pin;- Equation: position of the nth pin relative to the patch center;- β: phase constant.

[0078] This equation is directly analogous to the array factor in antenna array theory (Balanis,"Antenna Theory").

[0079] In the context of the condition for destructive interference, from classical array theory,destructive interference (nulls) occurs in a direction if:Equation

[0080] At θ = 180° (the back direction), if the phasor sum of contributions from all pins 310 iszero, then the radiated field in that direction vanishes. This is exactly the null condition.

[0081] Mathematical null formation, in the proposed structure, at θ = 180°, the total fieldbecomes:Etotal(180°) = Equation

[0082] If the diagonal pins 310 are symmetrically placed such that their contributions satisfy:Equation -(Afeed + Acenter pin)ThenEquation

[0083] This is a direct application of classical phasor cancellation in antenna arrays. Thus,based on classical array theory and superposition of fields, the diagonal shorting pins 310 arepositioned so that their phasor contributions cancel the backward radiation from the feed andcentral pin. This guarantees destructive interference at θ = 180°, resulting in a radiation null inthe backward direction while preserving constructive addition in the forward hemisphere.

[0084] As per the holistic radiation control mechanism, the combined feed and pinconfiguration thus establishes a holistic mechanism for radiation pattern control. The feedplacement along the central width line ensures low baseline back radiation and / increased frontto-back ratio. The central shorting pin further reduces residual backward fields by directlyopposing the feed's contribution. Finally, the diagonal shorting pins 310 reinforce thecancellation process through controlled phase contributions, ensuring both the E-plane and Hplane fields approach zero at θ = 180°. The outcome is a radiation null in the backwarddirection, coupled with a broad and stable forward lobe. Although the null direction (θ = 180°)can be engineered with high predictability, the depth of the null is not absolute and depends onmultiple interrelated factors line phase alignment (deviations in phase may occur due to due tofabrication tolerances, pin position errors, or substrate losses), Mutual Coupling ( Interactionbetween pins 310 and the patch surface currents can modify the effective amplitudes andphases), Polarization Components (The E-plane and H-plane may not both exhibit identicalnull depths due to differing modal interactions.) etc. These are not only determined by the feedand shorting pin configuration but are also influenced by other structural features of the patch,such as slots, notches, perturbations, or the overall patch geometry.

[0085] In the context of practical impact on back radiation, the destructive interference createdby the shorting pins 310 results in a substantial reduction of energy radiated toward thebackside of the antenna. While the exact depth of the null depends on practical considerationssuch as amplitude balance, phase alignment, mutual coupling, and patch modifications, theexistence of the null direction is robust. Importantly, the forward radiation remains wide andstable, providing excellent coverage for mobile and wearable devices while minimizingexposure to the user.

[0086] Technical benefits of the configuration: This strategy offers several technicaladvantages. First, it achieves effective back radiation suppression without requiring reflectors,EBG surfaces, or absorptive materials. Second, it directly reduces SAR levels, which is vitalin wearable and mobile scenarios. Third, the configuration preserves a wide beam width in theforward hemisphere, which provides robust coverage for mobile communication. Finally, thedesign remains compact, planar, and PCB-compatible, ensuring easy integration intocommercial devices.

[0087] In summary, the mechanism of back-radiation suppression arises because strategicallyplaced shorting pins 310 act as controlled secondary radiators. Their induced fields interferedestructively with the patch's backward radiation, creating a null at θ = 180°. This passive andgeometry-driven technique not only reduces SAR but also preserves forward coverage, makingit a simple yet powerful solution for antenna designs in compact, body-centric wirelessapplications.

[0088] Figures 7A-7B illustrate tabular representations of simulated radiation characteristicsof the proposed design across multiple operating frequencies, according to an embodiment ofthe present disclosure. A comprehensive electromagnetic simulation was performed for themicrostrip patch antenna 300 across multiple frequency bands, followed by a comparativeevaluation against state-of-the-art configurations documented in prior literature.

[0089] The analysis is supported by detailed simulation results that demonstrate theeffectiveness of the shorted patch antenna in reducing SAR, achieving structural compactness,and maintaining high radiation efficiency. For clarity, these results are presented alongsidebenchmark designs operating in the 2.45 GHz ISM band, enabling a direct comparison ofphysical dimensions, operating characteristics, and SAR values. This comparative frameworkprovides a clear perspective on the performance advantages of the disclosed design relative toconventional and advanced SAR reduction techniques.

[0090] A parametric analysis was conducted to establish a scalable and generalized designmethodology for shorted microstrip patch antennas intended to suppress backward radiationand enhance beam directivity. Multiple antenna configurations were developed for operationin 4G, 5G, and sub-6 GHz communication systems, with particular emphasis on minimizingradiation toward the user to reduce SAR.

[0091] Each configuration comprises a compact, single-layer rectangular patch mounted on adielectric substrate 402 and supported by five strategically positioned shorting pins 310. Thesepins 310 were introduced to manipulate surface current distribution and suppress backwardradiation. Ten design variants were generated by varying patch dimensions, ranging from 20mm to 40 mm, and altering shorting pin placements. The objective was to examine theinfluence of these structural modifications on electromagnetic behavior and derive generalizeddesign principles applicable across multiple frequency bands.

[0092] The microstrip patch antenna 300 configurations were evaluated against keyelectromagnetic parameters, including reflection coefficient (S11) and impedance bandwidth,gain and directivity, and radiation pattern characteristics with emphasis on null formation at θ= 180°.

[0093] Simulation results, summarized in Figures 7A-7B, confirm that all ten design variantsachieved satisfactory impedance matching within their intended frequency bands. The S11plots exhibited well-defined resonances with acceptable bandwidths, primarily influenced bypatch dimensions and shorting pin placement.

[0094] A consistent observation across all configurations was the formation of a radiation nullat θ = 180°, validating effective suppression of backward radiation. This phenomenon isattributed to the symmetrical arrangement of shorting pins 310, which induces opposingcurrent phases that cancel backward-directed fields. While minor variations in null depth andsymmetry were noted among designs, the persistence of this feature underscores the criticalrole of shorting pins 310 in controlling radiation directionality.

[0095] The gain performance of the microstrip patch antenna 300 remained within practicallimits for wireless applications, with only marginal differences observed betweenconfigurations. Furthermore, shorting pin placement was found to significantly influence bothresonant frequency and impedance bandwidth, establishing it as a key parameter for finetuning antenna performance.

[0096] Figure 8 illustrates a tabular representation of simulated radiation characteristicscorresponding to different patch geometries, according to an embodiment of the presentdisclosure.

[0097] To extend the scope of the disclosed design methodology, additional antennaconfigurations were analyzed by varying patch geometries and the positioning of shorting pins310. These alternative embodiments consistently exhibited null formation at θ = 180°, althoughminor variations in radiation symmetry and lobe shaping were observed. The simulation resultscorresponding to these extended configurations are presented in Figure 8.

[0098] The observed performance trends confirm the repeatability and robustness of thedisclosed approach. It is further contemplated that optimization of parameters such as patchgeometry, shorting pin arrangement, and substrate characteristics may yield additionalimprovements in SAR reduction, forward gain, and operational bandwidth.

[0099] The parametric analysis establishes that the microstrip patch antenna 300, incorporatingshorting pins 310, provides a reliable and scalable solution for achieving compact, low-SARantenna designs. These findings offer significant design insights for next-generation wirelesscommunication systems, where minimizing user exposure to electromagnetic energy whilemaintaining high antenna performance is critical.

[0100] Integration of shorting pins 310 within the microstrip patch antenna 300 structureresulted in a substantial reduction in SAR values. This improvement is attributed to theredistribution of surface currents, which effectively suppresses backward radiation toward theuser. By attenuating rearward radiation components, the shorting pins 310 reduce localizedelectric field intensities within a human phantom model, thereby mitigating RF energyabsorption. The table illustrates SAR values before and after the implementation of shortingpins 310, demonstrating a consistent reduction trend and validating the efficacy of the disclosedtechnique in enhancing user safety without compromising antenna functionality.Table Comparative SAR Estimates for Antenna Configurations with and withoutShorting Pins

[0101] Minor variations in the listed frequencies (for example, 1.85 vs 1.82 GHz and 2.06 vs.2.12 GHz) occur because the values used correspond to the centre frequencies within the sameoperating bands. As the antennas operate over identical bands, the SAR values are effectivelycomparable across these cases.Table Specific Reduction Factor Estimates for 1 g and 10 g Tissue Volumes With andWithout Shorting PinsTable Consolidated SAR and SRF Data for antenna configurations with and without shortingpins

[0102] Minor variations in the listed frequencies (for example, 1.85 vs 1.82 GHzand 2.06 vs. 2.12 GHz) occur because the values used correspond to the centrefrequencies within the same operating bands. As the antennas operate over identicalbands, the SAR values are effectively comparable across these cases.

[0103] To quantify the effectiveness of the shorting pin mechanism in reducingSAR, the metric Specific Reduction Factor (SRF) is employed. SRF represents thepercentage reduction in SAR achieved by incorporating shorting pins 310 into theantenna structure relative to the SAR values of an equivalent antenna withoutshorting pins 310. This metric provides a clear and quantifiable measure of thereduction in electromagnetic energy absorption by human tissue attributable to thedisclosed design modifications. SRF is defined for both 1 g and 10 g averagingvolumes as described herein:Equation- SAR1g, before and SAR10g, before are the initial SAR values (prior tointroducing shorting pins).- SAR 1g, after, and SAR 10g, after are the SAR values measured aftermodification.

[0104] These expressions quantify the percentage improvement and provide anintuitive understanding of the effectiveness of SAR suppression mechanisms. Ahigher SRF value implies a more substantial reduction in SAR and, hence, greatercompliance with safety standards. The SAR was computed under standardizedconditions for both 1g and 10g tissue averaging using simulation models adheringto IEEE / IEC guidelines. The results, summarized in the Table, show SAR valuesat different test conditions for both configurations (with and without shorting pins),along with the calculated SRF values for each case.

[0105] The analysis of SRF results clearly highlights the significant SARsuppression capability of the shorted patch antenna. For 1g averaging, the SARvalues without shorting pins range from 0.44 to 2.05 W / kg, whereas the values withshorting pins drop considerably to a range between 0.17 and 0.45 W / kg. This leadsto SRF improvements ranging from 23.21% to 87.85%, with most values exceedingthe 40% mark, indicating strong mitigation effects.

[0106] A similar trend is observed for 10g averaging, where SAR without shortingpins lies between 0.18 and 0.90 W / kg, and the modified design reduces it down to0.09-0.29 W / kg. The corresponding SRF values range from 20.00% to 87.67%,demonstrating the efficacy of the shorting pin method in reducing deeper tissueexposure as well.

[0107] This substantial improvement in SAR values across tissue penetrationmodels validates the robustness of the proposed approach. More importantly, theconsistency of SRF across diverse simulation conditions and input configurationsreveals the repeatable and generalized nature of the technique, making it adaptableacross a wide range of wearable and handheld device scenarios. The methodologycan thus serve as a foundation for the development of a unified and systematicdesign strategy aimed at controlling radiation exposure in compact antenna systems.

[0108] The SRF facilitates a comparative assessment by highlighting how much theSAR value has decreased relative to its original (unmodified) level. This metric isparticularly useful when benchmarking different SAR reduction techniques orevaluating optimization strategies across various antenna configurations.Table

[0109] Figure 9 illustrates a sequence flow diagram 900 detailing the operationalaspects of the microstrip patch antenna 300, according to an embodiment of thepresent disclosure.

[0110] The disclosed method 900 begins with the excitation of a rectangular patchantenna (e.g., microstrip patch antenna 300) through an input feed, which inducesa controlled current distribution across the patch surface (Step 901). The patchoperates in its fundamental transverse magnetic (TM10) mode, establishing theprimary radiating mechanism (Step 902).

[0111] To enhance the front-to-back radiation ratio and suppress undesiredbackward radiation, the central shorting pin is introduced into the patch structure(Step 903). This central pin effectively cancels residual backward currents byaltering the current flow pattern. Subsequently, the diagonal shorting pin isincorporated to introduce phase-shifted secondary currents (Step 904). Thesesecondary currents are strategically generated to achieve field control, enablingconstructive and destructive superposition of radiated fields in the far-field region(Step 905).

[0112] The interaction between the primary patch currents and the shorting-pininducedcurrents results in controlled interference patterns. Specifically, destructiveinterference occurs at the θ = 180°, thereby nullifying backward radiationcomponents (Step 906). This mechanism ensures that radiation directed toward theuser is effectively suppressed, thereby reducing localized electric field intensitiesand minimizing SAR without compromising antenna performance.

[0113] In one or more exemplary embodiments, the microstrip patch antenna 300comprises the ground plane 403, the dielectric substrate 402 disposed on the groundplane 403, and the radiating patch 401 positioned on the dielectric substrate 402. Afeed element is coupled to the central width axis of the radiating patch 401 and isconfigured to excite the patch for signal transmission. The antenna further includesa plurality of shorting pins electrically connecting the radiating patch 401 to theground plane 403, each shorting pin being strategically positioned at predeterminedlocations relative to the radiating patch 401 to alter the radiation characteristics andgenerate a radiation null in the back lobe of the far-field pattern. The dielectricsubstrate 402 incorporates a plurality of vias for accommodating the shorting pins.In certain configurations, at least two shorting pins are positioned at angular offsetsof +60° and -60° with respect to the central feed axis, while additional pins may belocated at +120° and -120° or diametrically opposite to the feed position at ±90°along the same axis. The field null is achieved through a passive arrangement of theradiating and coupling elements. In one embodiment, the feed element comprises acoaxial probe located along the central width axis of the radiating patch 401, withat least one shorting pin symmetrically positioned opposite to the feed elementalong said axis. The radiating patch 401 is generally rectangular in shape, althoughalternative geometries may be employed without departing from the scope of theinvention.

[0114] Various techniques for reducing Specific Absorption Rate (SAR) in antennasystems, particularly those operating within the 2.45 GHz ISM band, have beenextensively explored in prior art. Reported approaches include switchable patchconfigurations, substrate-integrated waveguide (SIW) structures, metamaterialbased geometries, wearable antenna designs, electromagnetic bandgap (EBG)backed structures, and magneto-electric dipoles. While these techniques achievevarying degrees of SAR mitigation, they typically exhibit significant differences indesign complexity, physical footprint, and overall operational efficiency.

[0115] A consolidated evaluation of representative conventional solutions utilizesphysical dimensions, operating frequencies, and normalized SAR values (at 1 Winput power) under both 1 g and 10 g averaging conditions. This comparativeassessment reveals that numerous conventional and advanced designs continue toexhibit SAR levels approaching regulatory limits.

[0116] For example, the switchable patch antenna disclosed by the conventionalsolution and the spiral inverted-F dual-mode button antenna described by anotherconventional solution report SAR values exceeding 3.9 W / kg (1 g), which are nearthe permissible thresholds. Similarly, larger and structurally complex designs, suchas EBG-backed microstrip antennas and slotted monopole configurations,demonstrate SAR values above 2 W / kg (10 g), raising concerns for applicationsinvolving proximity to the human body.

[0117] In contrast, the disclosed shorted patch antenna (e.g., microstrip patchantenna 300) achieves substantial SAR reduction while maintaining a compactform factor of approximately 39 x 27 mm². Empirical results indicate SAR valuesof 0.71 W / kg for 1 g tissue averaging and 0.09 W / kg for 10 g tissue averaging, bothof which not only comply with but significantly surpass international safetystandards prescribed by regulatory authorities such as the FCC and ICNIRP.Notably, this improvement is realized without incorporating complex structuralmodifications or auxiliary components. The reduction is primarily attributed to theintegration of shorting pins within the radiating patch, which effectively suppressesbackward radiation and minimizes user exposure.

[0118] The disclosed microstrip patch antenna 300 design offers multipleadvantages over conventional techniques. Its compact geometry facilitates seamlessintegration into portable and wearable wireless devices, while the shorting pinimplementation ensures design simplicity and manufacturability, eliminatingreliance on material-intensive or intricate fabrication processes. Furthermore, thedesign achieves SAR reduction without compromising radiation efficiency, as theredistribution of surface currents within the patch enhances both exposuremitigation and radiation characteristics. Collectively, these attributes establish thedisclosed antenna as a practical and scalable solution for achieving user safetyalongside device miniaturization.

[0119] The comparative analysis underscores that strategic structural modificationscan deliver superior SAR performance without resorting to external components orcomplex design methodologies. Consequently, the disclosed shorted patch antennarepresents a technically robust and adaptable solution for next-generation wirelessplatforms, where compactness, user-centric safety, and regulatory compliance arecritical design priorities.

[0120] The disclosed shorting pin-loaded microstrip patch antenna (microstrippatch antenna 300), incorporating back-radiation suppression and SAR reduction,is designed for diverse applications across modern wireless communication systemsand body-centric networks.a. In mobile and handheld devices, the antenna ensures compliance with SARlimits while maintaining robust signal coverage, improving powerefficiency by minimizing radiation in non-functional directions, andenhancing call quality and data throughput for smartphones, tablets, andIoT devices.b. For wearable and biomedical systems, it is optimized for Wireless BodyArea Networks (WBANs) deployed in health-monitoring sensors, smartwearables, and fitness trackers, reducing electromagnetic absorption inbiological tissues to improve safety and reliability, while enabling superiortelemetry and remote patient monitoring.c. In next-generation wireless infrastructure, including 5G and beyond, theantenna supports advanced techniques such as MIMO and beamformingfor terminals and base stations, facilitates low-SAR configurations for IoTecosystems and AI-integrated smart devices, and enhances connectivityfor smart environments, autonomous vehicles, and Industry 4.0deployments.d. Additionally, in satellite and aerospace communication systems, thedesign suppresses back-lobe radiation to ensure high signal fidelity andprovides highly directional radiation patterns essential for space borne anddefense-grade communication.e. For radar and military applications, the antenna is suitable for low-profiletactical systems requiring precise radiation control and contributes tostealth technology by enabling radiation pattern management for reduceddetectability.

[0121] While specific language has been used to describe the present subjectmatter, any limitations arising on account thereof, are not intended. As would beapparent to a person in the art, various working modifications may be made to themethod in order to implement the inventive concept as taught herein. The drawingsand the foregoing description give examples of example embodiments. Thoseskilled in the art will appreciate that one or more of the described elements maywell be combined into a single functional element. Alternatively, certain elementsmay be split into multiple functional elements. Elements from one exampleembodiment may be added to another example embodiment.

Claims

1. A microstrip patch antenna (300) comprising: a ground plane; a dielectric substrate disposed on the ground plane; a radiating patch disposed on the dielectric substrate; a feed element connected to the central width axis of the radiating patch, wherein the feed element is configured to excite the radiating patch; and a plurality of shorting pins electrically connecting the radiating patch to the ground plane, wherein each of the plurality of shorting pins is positioned at a predetermined location relative to the radiating patch to modify the radiation pattern, thereby forming a radiation null in a back lobe of the antenna's far-field pattern.

2. The microstrip patch antenna (300) as claimed in claim 1, wherein the dielectric substrate comprises a plurality of vias configured to accommodate the plurality of shorting pins.

3. The microstrip patch antenna (300) as claimed in claim 1, wherein at least two of the plurality of shorting pins are positioned at +60° and -60° with respect to a central feed axis of the radiating patch.

4. The microstrip patch antenna (300) as claimed in claim 1, wherein at least two of the plurality of shorting pins are positioned at +120° and -120° with respect to a central feed axis of the radiating patch.

5. The microstrip patch antenna (300) as claimed in claim 1, wherein at least one of the plurality of shorting pins is positioned diametrically opposite to the feed position at ±90° with respect to a central feed axis of the radiating patch.

6. The microstrip patch antenna (300) as claimed in claim 1, wherein the field null is generated by a passive configuration of the radiating and coupling elements.

7. The microstrip patch antenna (300) as claimed in claim 1, wherein the feed element is a coaxial probe located at the central width axis of the radiating patch and at least one shorting pin is positioned at a location symmetrically opposite to the feed element along said axis of the radiating patch.

8. The microstrip patch antenna (300) as claimed in claim 1, wherein the radiating patch has a rectangular shape.

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