Design and Analysis of an Apple-Shaped Microstrip Patch Antenna for 2.4 GHz Applications

Haldia Institute of Technology Publishing Int.J.HIT.TRANSC:ECCN.Vol.12: Issue 1 A (202 Available Online at www.hithaldia.in/locate/ECCN *Corresponding Address [email protected] ORIGINAL CONTRIBUTION Design and Analysis of an Apple 2.4 GHz Applications 1 Shyamala C, 2 Shivakumar M, 3 Vedha A S, 1 Associate Professor, Department of Electronics and Communication Engineering, GSSS Institute of Engineering and Technology for Women, Mysuru, Visvesvaraya Technological University, Belagavi, Karnataka, India 2 Principal & Professor, Department of Electronics and Technology for Women, Mysuru, Visvesvaraya Technological University, Belagavi, Karnataka, India 3 Project Assistant, Department of Electronics and Communication Engineering, GSSS Institute of Engi for Women, Mysuru, Visvesvaraya Technological University, Belagavi, Karnataka, India 4 Professor, Department of Electronics and Communication Engineering, GSSS Institute of Engineering and Technology for Women, Mysuru, Visvesvaraya Te chnological University, Belagavi, Karnataka, India 5 Professor, Department of Electronics and Communication Engineering, Malnad College of Engineering, Hassan, Karnataka, India, Email Id: [email protected] ABSTRACT This paper presents the design and analysis of a novel apple GHz, specifically engineered for compact and robust wireless communication systems. The antenna structure is realized on a dielectric substrate with a relative permittivity of 4.4 and features a uniquely contoured patch geometry formed by a polylinedefined layout. The prototype, with dimensions of 40 mm × 45 mm and fed by a microstrip line (14 mm × 2 mm), exhibi GHz to 2.5271 GHz. The radiation characteristics and bandwidth are optimized for applications in the ISM band, particularly for vehicular and IoT environments that require compactness a measured results demonstrate strong agreement with the simulated data, confirming the antenna’s operational reliability and geometric effectiveness. This study validates the apple integ ration in modern vehicular communication frameworks. KEYWORDS : Biometric Verification, Fingerprint Authentication, ESP32 Database, Portable Attendance System, Student Authentication, Face recognition 1. INTRODUCTION The 2.4 GHz Industrial, Scientific, and Medical (ISM) frequency band supports a broad range of shortrange wireless standards, including Wi Bluetooth, ZigBee, and emerging low networks. These applications demand antennas Haldia Institute of Technology Publishing International Journal of HIT Transaction on ECCN A (202 5) Page 32-39 Available Online at www.hithaldia.in/locate/ECCN All Rights Reserved [email protected] DOI: 10.5281/zenodo.17499858 Design and Analysis of an Apple - Shaped Microstrip Patch Antenna for Vedha A S, 4 Jayanth J, 5 Ravikiran H K Professor, Department of Electronics and Communication Engineering, GSSS Institute of Engineering and Technology for Women, Mysuru, Visvesvaraya Technological University, Belagavi, Karnataka, India Principal & Professor, Department of Electronics and Communication Engineering, GSSS Institute of Engineering and Technology for Women, Mysuru, Visvesvaraya Technological University, Belagavi, Karnataka, India Project Assistant, Department of Electronics and Communication Engineering, GSSS Institute of Engi neering and Technology for Women, Mysuru, Visvesvaraya Technological University, Belagavi, Karnataka, India Professor, Department of Electronics and Communication Engineering, GSSS Institute of Engineering and Technology for chnological University, Belagavi, Karnataka, India Professor, Department of Electronics and Communication Engineering, Malnad College of Engineering, Hassan, Karnataka, This paper presents the design and analysis of a novel apple - shaped microstrip patch antenna operating at 2.4 GHz, specifically engineered for compact and robust wireless communication systems. The antenna structure is realized on a dielectric substrate with a relative permittivity of 4.4 and features a uniquely contoured patch defined layout. The prototype, with dimensions of 40 mm × 45 mm and fed by a microstrip line (14 mm × 2 mm), exhibi ts a simulated impedance bandwidth of 83.5 MHz, spanning from 2.4436 GHz to 2.5271 GHz. The radiation characteristics and bandwidth are optimized for applications in the ISM band, particularly for vehicular and IoT environments that require compactness a nd efficient performance. The measured results demonstrate strong agreement with the simulated data, confirming the antenna’s operational reliability and geometric effectiveness. This study validates the apple - shaped antenna as a viable candidate for ration in modern vehicular communication frameworks. Biometric Verification, Fingerprint Authentication, ESP32 -CAM, FireDatabase, Portable Attendance System, Student Authentication, Face recognition The 2.4 GHz Industrial, Scientific, and Medical (ISM) frequency band supports a broad range of range wireless standards, including Wi -Fi, Bluetooth, ZigBee, and emerging low -power IoT networks. These applications demand antennas that are compact, inexpensive, and straightforward to integrate into planar hardware platforms [7]. Microstrip patch antennas (MPAs) have been widely adopted for such use due to their low profile, ease of fabrication using printed circuit board (PCB) techn iques, and predictable input impedance characteristics [4],[11],[14]. However, conventional rectangular patches often provide a narrow impedance bandwidth, exhibit International Journal of HIT Transaction on ECCN ISSN: 0973-6875 P a g e | 32 Shaped Microstrip Patch Antenna for Professor, Department of Electronics and Communication Engineering, GSSS Institute of Engineering and Communication Engineering, GSSS Institute of Engineering and neering and Technology Professor, Department of Electronics and Communication Engineering, GSSS Institute of Engineering and Technology for Professor, Department of Electronics and Communication Engineering, Malnad College of Engineering, Hassan, Karnataka, shaped microstrip patch antenna operating at 2.4 GHz, specifically engineered for compact and robust wireless communication systems. The antenna structure is realized on a dielectric substrate with a relative permittivity of 4.4 and features a uniquely contoured patch defined layout. The prototype, with dimensions of 40 mm × 45 mm and fed by a ts a simulated impedance bandwidth of 83.5 MHz, spanning from 2.4436 GHz to 2.5271 GHz. The radiation characteristics and bandwidth are optimized for applications in the ISM band, nd efficient performance. The measured results demonstrate strong agreement with the simulated data, confirming the antenna’s operational shaped antenna as a viable candidate for base Real-time that are compact, inexpensive, and straightforward to integrate into planar hardware platforms [7]. Microstrip patch antennas (MPAs) have been widely adopted for such use due to their low profile, ease of fabrication using printed circuit iques, and predictable input impedance characteristics [4],[11],[14]. However, conventional rectangular patches often provide a narrow impedance bandwidth, exhibit Shyamala Cet. al./Int.J.HIT.TRANSC:ECCN. Vol.12: Issue 1A (2025) ISSN: 0973-6875 DOI: 10.5281/zenodo.17499858 P a g e | 33 performance degradation with the substrate variations, and offer limited gain when realized on low-cost dielectric materials. Consequently, a vari-ety of techniques—such as patch-shape modifications, ground-plane alterations, and the incorporation of engineered surfaces—have been explored to enhance performance within the 2.4– 2.5 GHz band [1], [2] [4], [5], [6], [10], [12], [15]. Recent developments include low-cost MPAs with 3D-printed enhancements for improved bandwidth and gain [2], and antennas employing meta surface or artificial magnetic conductor (AMC) backings to achieve compact circular polarization (CP) at 2.45 GHz [1], [5]. Shaping the patch element is an effective approach for improving performance without increasing the antenna stack height. Modifying the current path through non-rectangular geometries enables miniaturization, bandwidth broadening, and multiresonance operation while retaining a single-layer configuration. Shapes inspired by symbols, logos, or product themes—combined with structural elements such as slots and notches—have been shown to deliver dual or triple resonances around 2.4 GHz, as well as enhance visual integration into consumer products [6],[8],[12]. Partial ground planes or parasitic edges are often added to further adjust impedance and radiation characteristics. Addition-ally, defected ground structures (DGS) are commonly used to suppress cross-polarization and improve impedance bandwidth, forming an established design tool for planar antennas [2],[4],[5]. The use of artificial surfaces, including AMCs and meta surfaces, offers further opportunities for 2.4 GHz antenna optimization. By altering the local boundary conditions beneath or around the patch, these surfaces can support constructive image currents, reduce profile, and enable CP operation within a compact footprint [5]. For example, a corner-truncated patch over an AMC surface has been demonstrated to produce wider axialratio bandwidth and stable boresight radiation patterns, which are advantageous for devices prone to polarization mismatch [1], [5]. For mass production, the antenna design must be tolerant to fabrication variations, use minimal additional components, and maintain performance on affordable substrates such as FR-4. Among feeding methods, coaxial probe feeding has been shown to achieve better return-loss and voltage standing wave ratio (VSWR) performance at 2.4 GHz compared to inset feeding when implemented under similar design conditions [3]. Following this approach, the proposed antenna targets return-loss below −10 dB over the 2.40– 2.50 GHz band with realized gain above 3 dBi. If device height permits, further enhancement can be achieved using AMC superstrates or lightweight 3D-printed structures [1], [2]. The proposed apple-shaped microstrip patch antenna, intended for compact and robust wireless communication in the 2.4 GHz ISM band, was designed and optimized using HFSS software. The antenna is fabricated on a dielectric substrate with a relative permittivity of 4.4, featuring a uniquely contoured patch defined through a polyline-based layout. The prototype, measuring 40 mm × 45 mm, is excited via a 14 mm × 2 mm microstrip feed line. For experimental validation, the antenna was constructed on a FR4 substrate to assess real-world performance. A simple apple-shaped microstrip section was connected to the SMA feed port. The optimized ground-plane configuration main-tained a stable gain response while simultaneously improving bandwidth and radiation efficiency. These findings confirm that the combination of the apple-shaped radiating patch and ground struc-ture provides a balanced trade-off between compact form factor, bandwidth, and efficiency, making it well-suited for integration into space-constrained wireless systems. 2. Antenna Design 2.1 Design Objective and Constraints The antenna targets the 2.4 GHz ISM band and is intended for compact, mechanically robust wireless systems. The layout is restricted to a 40 mm × 45 mm substrate (“board window”) while maintaining a standard 50-Ω input interface and manufacturable geometry suitable for FR-4–class processes. The design emphasizes three outcomes: (i) reliable matching across the intended Wi-Fi/ZigBee band, (ii) stable broadside ISSN: 0973-6875 DOI: 10.5281/zenodo.17499858 radiation with minimal crosspolarization, and (iii) tolerance to routine PCB fabrication variations. 2.2 Substrate, Stackup, and Global Dimensions The radiator is implemented on a dielectric substrate with relative permittivity 4.4 and thickness 1.6 mm. Copper is realized as full weight cladding on both si des. The overall board size is 40 mm (width) by 45 mm (length). The top layer hosts the feed line and the shaped radiating patch; the bottom layer provides the ground plane that is selectively perturbed by a rectangular slot as shown in figure 1 to enhance bandwidth and facilitate impedance control (a) Frontend of the proposed antenna. (b) back side ground plane Fig.1. Antenna topology: (a) front patch, (b) back side ground plane. Unit: mm. 2.3 Radiating Element: AppleShaped Polyline Patch To meet the footprint constraint without sacrificing resonance placement, the radiator employs an “appleshaped” contour that lengthens and redistributes the surface current path Shyamala Cet. al./Int.J.HIT.TRANSC:ECCN. Vol. DOI: 10.5281/zenodo.17499858 P a g e polarization, and (iii) tolerance to routine PCB fabrication variations. 2.2 Substrate, Stackup, and Global Dimensions The radiator is implemented on a dielectric substrate with relative permittivity 4.4 and thickness 1.6 mm. Copper is realized as full - des. The overall board size is 40 mm (width) by 45 mm (length). The top layer hosts the feed line and the shaped radiating patch; the bottom layer provides the ground plane that is selectively perturbed by a rectangular slot bandwidth and Fig.1. Antenna topology: (a) front patch, (b) back Shaped To meet the footprint constraint without sacrificing resonance placement, the radiator shaped” contour that lengthens and redistributes the surface current path compared with a plain rectangle of the same bounding box. The contour is defi polyline at z = 1.6 mm using the following vertex list (units in millimeters): (34, 20), (36, 14), (8, 6), (8, 6), (8, 14), (14, 20), (8, 26), (8, 34), (8, 34), (36, 26), and back to (34, 20). Duplicate points are kept intentionally to cont segment joins during import. This shape introduces gentle curvature and two locally narrowed regions (“stem” and side necks) that provide additional degrees of freedom for fine control of input reactance and for mild multi resonant behavior. The fi nal contour was adjusted to center the electrical response in the upper portion of the 2.4 GHz band, leaving margin for processinduced dielectric variability 2.4 Feeding Network and 50Ω A microstrip line on the top layer (length 14 mm, width 2 mm) excites the patch from the board edge through a standard SMA connector. The 2 mm width is chosen to be close to a 50 characteristic on the selected stackup while also serving as a predictable series element in the overall match. This transiti compact way to nudge the real part of the input impedance toward 50 Ω and to can residual reactance without resorting to discrete components. The feed launch is supported by a tight via fence to ground around the connector footprint t o minimize parasitic radiation and to stabi-lize the reference plane. 2.5 Parametric Tuning Strategy Design proceeded in three passes: •Baseline sizing. A conventional rectangular reference patch and a 2mm feed were used to verify that a 40 mm × 45 mm aperture can support resonance in the intended band on the chosen substrate. This step establishes a starting point for current path length and feed location. •Contour shaping. The apple polyline vertices were tuned to pull the resonance into the band center and to manage local current bottlenecks at the stem and shoulder regions.Small adjust (1– 2 mm) to the lobe curvature and stem width Vol. 12: Issue 1A (2025) P a g e | 34 compared with a plain rectangle of the same bounding box. The contour is defi ned as a closed polyline at z = 1.6 mm using the following vertex list (units in millimeters): (34, 20), (36, 14), (8, 6), (8, 6), (8, 14), (14, 20), (8, 26), (8, 34), (8, 34), Duplicate points are kept intentionally to cont rol segment joins during import. This shape introduces gentle curvature and two locally narrowed regions (“stem” and side necks) that provide additional degrees of freedom for fine control of input reactance and for mild multi - nal contour was adjusted to center the electrical response in the upper portion of the 2.4 GHz band, leaving margin for induced dielectric variability . Ω Interface A microstrip line on the top layer (length 14 mm, mm) excites the patch from the board edge through a standard SMA connector. The 2 - mm width is chosen to be close to a 50 -Ω characteristic on the selected stackup while also serving as a predictable series element in the overall match. This transiti on offers a compact way to nudge the real part of the input Ω and to can -cel small residual reactance without resorting to discrete components. The feed launch is supported by a tight via fence to ground around the connector o minimize parasitic radiation and to 2.5 Parametric Tuning Strategy Design proceeded in three passes: •Baseline sizing. A conventional rectangular mm feed were used to aperture can support resonance in the intended band on the chosen substrate. This step establishes a starting point for current path length and feed location. •Contour shaping. The apple polyline vertices were tuned to pull the resonance into the band center and to manage local current bottlenecks at the stem and shoulder regions.Small adjust -ments 2 mm) to the lobe curvature and stem width ISSN: 0973-6875 DOI: 10.5281/zenodo.17499858 were especially effective for centering the match window and reducing sensitivity to copper etch bias. 2.6 Simulation Configuration All designs were modelled and optimized in Ansys HFSS Software. The antenna was excited using a waveguide port deembedded to the SMA reference plane. Openspace radiation boundaries were applied with at least a quarter - air margin on all sides. A local adaptive mesh refinement was used near the feed transition, the polyline corners, and the edges of the ground slot to stabiliz e the input impedance and radiation metrics. Convergence criteria were enforced on both |S11| magnitude and total radiated power to ensure that bandwidth and efficiency predictions were mutually consistent. 2.7 Fabrication and Layout Practices Copper clear ances of at least 0.3 mm were maintained around the polyline inflections to prevent overetching from distorting the targeted contour. The feed-topatch junction includes a small taper to mitigate current crowding. The ground plane around the connecto is stitched with vias at approximately 1.5 pitch, forming a quasicoaxial launch. The ground slot corners are filleted with a small radius to reduce field singularities and improve repeatability across fabrication lots. Silkscreen is kept away from highfield edge of the patch. 2.8 Tolerance, Robustness, and Repeatability Sensitivity sweeps were performed for ±5% variation in substrate permittivity and ±0.1 mm copper geometry bias. The apple contour showed benign shifts in center frequency wi minimal degradation in matching due to theassisted impedance smoothing. The 2 width provided acceptable margin against solder mask swell and plating variations. The overall layout maintained stable broadside patterns under these perturbations, indicating suitable robustness for low-cost manufacturing. 3. Results and Discussion Shyamala Cet. al./Int.J.HIT.TRANSC:ECCN. Vol. DOI: 10.5281/zenodo.17499858 P a g e effective for centering the match window and reducing sensitivity to copper etch All designs were modelled and optimized in Ansys HFSS Software. The antenna was excited embedded to the SMA space radiation boundaries - wavelength air margin on all sides. A local adaptive mesh refinement was used near the feed transition, the polyline corners, and the edges of the ground slot e the input impedance and radiation metrics. Convergence criteria were enforced on both |S11| magnitude and total radiated power to ensure that bandwidth and efficiency predictions 2.7 Fabrication and Layout Practices ances of at least 0.3 mm were maintained around the polyline inflections to etching from distorting the patch junction includes a small taper to mitigate current crowding. The ground plane around the connecto r is stitched with vias at approximately 1.5 –2.0 mm coaxial launch. The ground slot corners are filleted with a small radius to reduce field singularities and improve repeatability across fabrication lots. Silkscreen is field edge of the patch. 2.8 Tolerance, Robustness, and Repeatability Sensitivity sweeps were performed for ±5% variation in substrate permittivity and ±0.1 mm copper geometry bias. The apple contour showed benign shifts in center frequency wi th minimal degradation in matching due to theassisted impedance smoothing. The 2 -mm feed gin against solder - mask swell and plating variations. The overall layout maintained stable broadside patterns under indicating suitable robustness The proposed appleshaped microstrip patchantenna was evaluated through full simulations in Ansys HFSS Software, with performance metrics extracted for reflection coefficient (|S11|), impedance bandwidth, voltage standing wave ratio (VSWR), realized gain, directivity, and radiation patterns. The results demonstrate that the optimized geometry achieves stable operation across the intended 2.4 GHz ISM band with a compact form factor. 3.1 Reflection Coefficient and Bandwidth The simulated |S11| response of the proposed antenna is shown in Fig. 2. The antenna exhibits a welldefined resonance within the target frequency range, with the minimum |S11| occurring near the band center. The returnloss criterion is satisfied over a frequency range extending from 2.4436 GHz (m2) to 2.5271 GHz (m3), corresponding to an impedance bandwidth of approximately 83.5 MHz. This bandwidth is sufficient to cover the 2.4 GHz ISM alloca tion (2.400 with additional margin to accommodate fabrication tolerances and environmental detuning effects. The smooth |S11| curve and absence of secondary spurious resonances within the simulated span indicate that the combination of patch and the rectangular ground slot effectively suppresses higherorder modes while maintaining singlemode operation. The observed bandwidth improvement over a comparable rectangular patch on the same substrate can be attributed t elongated current path introduced by the polyline contour and the impedancesmoothing action of the defected ground structure. architecture for realtime performance [6]. Vol. 12: Issue 1A (2025) P a g e | 35 shaped microstrip patchantenna was evaluated through full -wave simulations in Ansys HFSS Software, with performance metrics extracted for reflection ance bandwidth, voltage standing wave ratio (VSWR), realized gain, directivity, and radiation patterns. The results demonstrate that the optimized geometry achieves stable operation across the intended 2.4 GHz ISM form factor. 3.1 Reflection Coefficient and Bandwidth The simulated |S11| response of the proposed antenna is shown in Fig. 2. The antenna exhibits defined resonance within the target frequency range, with the minimum |S11| center. The −10 dB loss criterion is satisfied over a frequency range extending from 2.4436 GHz (m2) to 2.5271 GHz (m3), corresponding to an impedance bandwidth of approximately 83.5 MHz. This bandwidth is sufficient to cover the tion (2.400 –2.4835 GHz) gin to accommodate fabrication tolerances and environmental The smooth |S11| curve and absence of secondary spurious resonances within the simulated span indicate that the combination of the apple-shaped patch and the rectangular ground slot effectively order modes while maintaining mode operation. The observed bandwidth improvement over a comparable rectangular patch on the same substrate can be attributed t o the elongated current path introduced by the polyline smoothing action of the defected ground structure. co-engineered time performance [6]. ISSN: 0973-6875 DOI: 10.5281/zenodo.17499858 Fig.2. S11 parameter of Proposed Apple Microstrip patch antenna. 3.2 Voltage Standing Wave Ratio (VSWR) Fig.3 presents the simulated VSWR of the antenna across the frequency range of interest. The VSWR remains below 2.0 over the entire matched band, Fig.3. VSWR parameter of Proposed Apple Microstrip patch antenna. with the lowest value occurring at the resonance frequency. A VSWR below 2 corresponds to return losses better than −9.54 dB, indicating a high degree of power transfer from the feed network to the radiating structure. The VSWR profile is symmetric about the resonance point, reflecting the impedance symmetry achieved through careful feed placement and matching network integration. 3.3 Realized Gain The realized gain of the proposed antenna, depicted in Fig.4, remains nearly constant across the matched band. The gain plateauing effect is desirable for systems requiring consistent link budgets over channel frequency variations, such as frequencyhopping or spread communications in the ISM band. The stable gain can be attributed to th e combined influence of the Shyamala Cet. al./Int.J.HIT.TRANSC:ECCN. Vol. DOI: 10.5281/zenodo.17499858 P a g e Fig.2. S11 parameter of Proposed Apple 3.2 Voltage Standing Wave Ratio (VSWR) Fig.3 presents the simulated VSWR of the antenna across the frequency range of interest. The VSWR remains below 2.0 over the entire matched band, Fig.3. VSWR parameter of Proposed Apple with the lowest value occurring at the resonance frequency. A VSWR below 2 corresponds to −9.54 dB, indicating a gree of power transfer from the feed network to the radiating structure. The VSWR ric about the resonance point, reflecting the impedance symmetry achieved through careful feed placement and matching - The realized gain of the proposed antenna, depicted in Fig.4, remains nearly constant across the matched band. The gain plateauing effect is desirable for systems requiring consistent link budgets over channel frequency variations, such as hopping or spread -spectrum communications in the ISM band. The stable gain e combined influence of the optimized ground slot location; which minimizes radiation cancellation at the lower and upper edges of the band and the controlled surface current distribution on the appleshaped patch. The maximum simulated realized gain is i range of 3– 3.5 dBi at boresight. This value is consistent with expectations for a compact, single layer microstrip radiator of the given aperture size, and represents a good compromise between bandwidth enhancement and radiation efficiency on a lossy FR4–class substrate. Fig.4. Gain of Proposed Apple Microstrip patch antenna. ]3.4 Directivity The simulated directivity, shown in Fig.5, follows a trend similar to the realized gain, with peak values slightly exceeding the realized gain due to radiat ion efficiency less than unity. The directivity pattern is broad in the principal planes, consistent with a fundamental TM10like mode modified by the nonrectangular contour. The slight increase in directivity at frequencies near the upper band edge is co nsistent with a modest narrowing of the main beam, which does not adversely impact coverage for omnidirectional or quasi deployment scenarios. Vol. 12: Issue 1A (2025) P a g e | 36 optimized ground slot location; which minimizes radiation cancellation at the lower and upper edges of the band and the controlled surface current shaped patch. The maximum simulated realized gain is i n the 3.5 dBi at boresight. This value is consistent with expectations for a compact, single - layer microstrip radiator of the given aperture size, and represents a good compromise between bandwidth enhancement and radiation efficiency Fig.4. Gain of Proposed Apple Microstrip patch The simulated directivity, shown in Fig.5, follows a trend similar to the realized gain, with peak values slightly exceeding the realized gain due to ion efficiency less than unity. The directivity pattern is broad in the principal planes, consistent like mode modified by rectangular contour. The slight increase in directivity at frequencies near the upper band edge nsistent with a modest narrowing of the main beam, which does not adversely impact coverage for omnidirectional or quasi -omnidirectional ISSN: 0973-6875 DOI: 10.5281/zenodo.17499858 Fig.5. Directivity of Proposed Apple Microstrip patch antenna 3.5 Radiation Patterns Farfield radiation patterns for the antenna are Fig.6. Radiation patterns for the designed antenna illustrated in Fig.6. The antenna exhibits a broadside radiation profile with symmetric main lobes in both the E-plane and Hplane cuts. Cross polarizatio n levels are low in the principal planes, indicating that the defected ground structure does not introduce significant unwanted polarization components. The Eplane pattern shows a nearly uniform main lobe with a halfpower beamwidth (HPBW) sufficient to e nsure coverage for typical fixed or mobile terminal applications. In the H pattern remains stable, with negligible back radiation. Minor variations in sidelobe levels across the band are attributed to the interaction Shyamala Cet. al./Int.J.HIT.TRANSC:ECCN. Vol. DOI: 10.5281/zenodo.17499858 P a g e Fig.5. Directivity of Proposed Apple Microstrip field radiation patterns for the antenna are Fig.6. Radiation patterns for the designed antenna illustrated in Fig.6. The antenna exhibits a broadside radiation profile with symmetric main plane cuts. Cross - n levels are low in the principal planes, indicating that the defected ground structure does not introduce significant unwanted polarization plane pattern shows a nearly uniform main power beamwidth (HPBW) nsure coverage for typical fixed or mobile terminal applications. In the H -plane, the pattern remains stable, with negligible back -lobe radiation. Minor variations in sidelobe levels across the band are attributed to the interaction between the patch cont our and the ground slot, but these remain well within acceptable limits for ISM applications. 3.6 Performance Summary Table 1. summarizes the key performance parameters of the proposed apple antenna. Parameter Value Operating frequency range 2.4436 Impedance bandwidth 83.5 MHz Peak realized gain 3– 3.5 dBi Directivity ~4 dBi VSWR across band < 2.0 Radiation pattern Broadside, stable HPBW Cross-polarization Low in principal planes The combination of a uniquely and a rectangular ground slot allows the design to achieve both bandwidth enhancement and stable radiation performance within a compact footprint. The observed impedance bandwidth exceeds the minimum requirement for the 2.4 GHz ISM band, wh ile the gain and efficiency are sufficient for typical WLAN, Bluetooth, and IoT applications. Moreover, the smooth radiation patterns and low crosspolarization suggest suitability for integration into devices where orientation variability is expected. 4. Conclusion A compact appleshaped microstrip patch antenna for 2.4 GHz ISMband applications has been presented, simulated, and analyzed. The design employs a uniquely contoured radiating element on a compact 40×45 mm2^22 substrate with Vol. 12: Issue 1A (2025) P a g e | 37 our and the ground slot, but these remain well within acceptable limits for ISM Table 1. summarizes the key performance parameters of the proposed apple -shaped patch Value 2.4436 – 2.5271 GHz 83.5 MHz 3.5 dBi ~4 dBi < 2.0 Broadside, stable HPBW Low in principal planes The combination of a uniquely contoured patch and a rectangular ground slot allows the design to achieve both bandwidth enhancement and stable radiation performance within a compact footprint. The observed impedance bandwidth exceeds the minimum requirement for the 2.4 GHz ISM band, ile the gain and efficiency are sufficient for typical WLAN, Bluetooth, and IoT applications. Moreover, the smooth radiation patterns and low polarization suggest suitability for integration into devices where orientation shaped microstrip patch antenna band applications has been presented, simulated, and analyzed. The design employs a uniquely contoured radiating element on a compact 40×45 mm2^22 substrate with Shyamala Cet. al./Int.J.HIT.TRANSC:ECCN. Vol.12: Issue 1A (2025) ISSN: 0973-6875 DOI: 10.5281/zenodo.17499858 P a g e | 38 εr=4.4, fed by a microstrip line and integrated with a rectangular defected ground slot for bandwidth enhancement. Simulation results demonstrate an impedance bandwidth of 83.5 MHz (2.4436– 2.5271 GHz), fully covering the ISM band with additional margin for fabrication tolerances. The antenna achieves a stable realized gain of 3–3.5 dBi across the matched band, broadside radiation patterns with low cross-polarization, and consistent VSWR below 2.0. The proposed configuration combines aesthetic form factor with functional advantages, offering improved bandwidth and pattern stability compared to a conventional rectangular patch of similar size. Its compact dimensions, low manufacturing complexity, and robustness to fabrication and environmental variations make it a suitable candidate for integration into WLAN, Bluetooth, ZigBee, and IoT devices. Future work may focus on implementing the design on low-loss substrates or incorporating parasitic/superstrate elements to further enhance gain, as well as adapting the geometry for dualor multi-band operation. The presented results confirm that creative radiator shaping, combined with simple ground-plane modifications, can yield high-performance, space-efficient antennas for modern wireless communication systems. 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