Multi-band c-slot filtering antenna for WIFI applications and interference control

Abstract

This disclosure proposes an antenna apparatus for use in a wireless communication device. The antenna apparatus comprises: a patch radiator configured to operate in a first frequency range; and at least one C-shaped slot formed on or within the patch radiator, wherein said at least one C-shaped slot is arranged to selectively reject signals in at least one second frequency band within or overlapping the first frequency range. The disclosure further proposes a wireless communication device comprising the proposed antenna apparatus.

Description

[0001] MULTI BAND C-SLOT FILTERING ANTENNA FOR WIFI APPLICATIONS AND INTERFERENCE CONTROL

[0002] TECHNICAL FIELD

[0003] The present disclosure pertains to the field of wireless communication systems, specifically to antenna technology for multiband and multi-link operation (MLO) in compact wireless access points. It focuses on innovative designs for multi-band directive antennas, integrating filtering capabilities to optimize performance across various frequency bands, including but not limited to Wi-Fi networks, as defined by the IEEE 802.11 framework of standards as well as further generations thereof and mmWave bands.

[0004] BACKGROUND

[0005] Wireless communication systems rely on multiple frequency bands for diverse applications. For instance, Wi-Fi networks commonly use the 2.4 GHz, 5 GHz, and 6 GHz frequency bands, while Bluetooth primarily operates in the 2.4 GHz band. Emerging technologies like Wi-Fi networks, as defined by the IEEE 802.11 framework of standards as well as further generations thereof have introduced MLO, which allow simultaneous communication across multiple bands between access points (APs) and associated stations (STAs).

[0006] Achieving efficient MLO requires antennas capable of isolating co-band signals while rejecting cross-band interference, a challenge exacerbated in compact AP designs. Conventional solutions often involve the use of pure RF filters such as BAW or SAW filters, which, despite their efficacy, can increase system cost, complexity, and insertion loss if dealing with a very high isolations as required by recent WLAN technology.

[0007] In particular, compact and cost-effective antennas that inherently possess filtering characteristics without relying on external filters are highly desirable. Existing designs, such as standard PCB or patch antennas, typically provide wideband radiation over specific bands but lack inherent filtering to address cross-band interference, limiting their utility in advanced multi-link scenarios. This becomes an even more challenging Electromagnetic Interference (EMI) issue as the number of MIMO antennas increases and product sizes continue to shrink.

[0008] SUMMARY

[0009] In view of the above, this disclosure aims to provide a low-cost and compact filtering antenna design that addresses the challenges of MLO in wireless communication systems, particularly for Wi-Fi networks, as defined by the IEEE 802.11 framework of standards as well as further generations thereof. An objective of the disclosure is to enhance signal quality and minimize cross-band interference through an integrated filtering capability. Another objective is to eliminate the need to rely only on high quality traditional external band-pass filters. By leveraging a cost-effective, compact, and scalable design, the proposed antenna maximizes performance across multiple frequency bands while reducing complexity, insertion loss, and production costs, thereby advancing the competitiveness of wireless access points.

[0010] These and other objectives are achieved by the embodiments of this disclosure as described in the independent claims. Advantageous implementations are further defined in the dependent claims.

[0011] According to a first aspect of this disclosure, an antenna apparatus for use in a wireless communication device is provided. The antenna apparatus comprises: a patch radiator configured to operate in a first frequency range; and at least one C-shaped slot formed on or within the patch radiator, wherein said at least one C-shaped slot is arranged to selectively reject signals in at least one second frequency band within or overlapping the first frequency range.This disclosure proposes a novel antenna design that enables selective rejection of signals in a second frequency band overlapping the primary operational band, improving overall antenna performance and reducing unwanted interference. By incorporating at least one C-shaped slot in the patch radiator, the antenna can “notch out” or suppress signals in a specific second frequency band, allowing stronger and more focused transmission / reception in the desired first frequency range.

[0012] In an implementation form of the first aspect, the dimensions of the at least one C-shaped slot are selected to define a center frequency of the second frequency band.

[0013] Varying the physical dimensions (e.g., length, width, curvature) of the C-shaped slot directly influences the resonant frequency of the notched band, enabling customization of the rejection frequency based on system needs. This configuration allows precise targeting of the unwanted frequency band to be rejected by controlling the slot dimensions, thereby optimizing interference suppression at a chosen center frequency.

[0014] In an implementation form of the first aspect, the position and / or the orientation of the at least one C-shaped slot relative to a feed point of the patch radiator is configured to adjust a bandwidth of the second frequency band.

[0015] By adjusting the location and / or angle of the C-shaped slot with respect to the feed point, designers can modify the antenna’s impedance characteristics in the rejected band, thereby controlling the notched bandwidth. This configuration facilitates fine-tuning of the bandwidth around the rejected frequency, providing flexibility in controlling how wide or narrow the notch is.

[0016] In an implementation form of the first aspect, the antenna apparatus further comprises a feed arrangement configured to operate in the first frequency range, wherein the feed arrangement comprises at least one of the following: capacitive coupling, microstrip feed, coaxial feed.

[0017] By leveraging standard feed methods (e.g., capacitive coupling, microstrip, or coaxial), the antenna structure provides a straightforward and reliable way to excite the patch radiator while preserving its intended performance characteristics. This configuration maintains robust signal feeding and matching at the primary operating band(s) through established feeding techniques, ensuring efficient power transfer to the patch radiator.

[0018] In an implementation form of the first aspect, the feed arrangement is configured as a single-feed comprising a single feed point.

[0019] A single feed point simplifies the antenna’s design and manufacturing, reducing both material usage and potential losses while maintaining functionality in the first frequency range. This configuration minimizes complexity and space requirements with a single-feed design while still achieving effective radiation in the chosen frequency band.

[0020] In an implementation form of the first aspect, the feed arrangement is configured as a dual-feed setup comprising a first feed port to allow radiation of a first polarization and a second feed port to allow radiation of a second polarization.

[0021] Dual-feed setup providing two feed ports allows the patch to radiate in two orthogonal polarizations, which can help overcome multipath or polarization mismatch issues commonly encountered in wireless systems. It enables multi-polarization operation within the same radiator structure, enhancing diversity performance and potentially improving radio link reliability between transmitter and receiver.In an implementation form of the first aspect, the patch radiator is configured such that the first feed port operates primarily in a lower portion of at least one Wi-Fi frequency band while substantially rejecting signals in an upper portion of said band, and such that the second feed port operates primarily in the upper portion of the same Wi-Fi frequency band while substantially rejecting signals in the lower portion thereof.

[0022] By assigning one feed port to handle the lower portion of a Wi-Fi band and another to handle the upper portion, each port can be optimized for its respective sub-band. The C-shaped slot(s) reinforce the rejection of signals in the undesired band segments. Such configuration permits split-band operation within a single radiator, selectively optimizing signal coverage for different portions of a Wi-Fi band while rejecting unwanted portions, thus improving overall spectral efficiency.

[0023] In an implementation form of the first aspect, the at least one C-shaped slot is configured to reduce boresight gain at the second frequency band, thereby enhancing RF channels orthogonality between transmitter and receiver for example in a configuration of WLAN multi-channels such as Wi-Fi networks, as defined by the IEEE 802.11 framework of standards as well as further generations thereof MLO.

[0024] Positioning the C-shaped slot to decrease antenna gain in the boresight direction at the second frequency band lowers unwanted signal overlap, thus improving port-to-port isolation for concurrent multi-band or MLO. This configuration reduces coupling and interference at the rejected band, leading to enhanced isolation between ports, especially beneficial in multi-link or Multiple-Input-Multiple-Output (MIMO) systems.

[0025] In an implementation form of the first aspect, the at least one C-shaped slot comprises a plurality of C-shaped slots, each C-shaped slot being independently configured to reject a respective second frequency band.

[0026] Optionally, multiple C-shaped slots may be formed on or within the patch radiator. Including multiple C-shaped slots allows each slot to be tuned to a different notched frequency, enabling the antenna to suppress multiple interference-prone bands within the same radiator structure. This configuration provides the ability to notch multiple distinct frequency bands simultaneously or independently, expanding the antenna’s flexibility for diverse wireless standards.

[0027] In an implementation form of the first aspect, the patch radiator has a substantially square shape with a side length selected to provide radiation coverage within the first frequency range, the side length being one of the following:

[0028] on the order of a few millimeters if the first frequency range is between about 40 GHz and 60 GHz,

[0029] on the order of tens of millimeters if the first frequency range is in a Wi-Fi band around 5 GHz or 6 GHz, on the order of tens of centimeters if the first frequency range is below about 1 GHz.

[0030] Choosing a square patch size suitable for the operating frequency range ensures proper resonant conditions. For example, side lengths of a few millimeters for 40-60 GHz, tens of millimeters for ~5-6 GHz, or tens of centimeters for sub-1 GHz. It ensures the antenna geometry is tailored for optimal radiation in the primary band, whether at millimeter- wave, mid-band (e.g., 5 or 6 GHz Wi-Fi), or sub-GHz frequencies.

[0031] In an implementation form of the first aspect, the C-shaped slot has a radius of about 10% to about 30% of the side length of the patch radiator.

[0032] Defining the slot’s radius as a fraction (10%— 30%) of the patch side length ensures the notch filter effect scales appropriately with the patch dimension, preserving rejection characteristics. This configuration provides design parameters for the C-shaped slot that are proportionally scaled with patch size, ensuring consistent performance across varied frequency ranges.In an implementation form of the first aspect, the antenna apparatus further comprises a plurality of the patch radiator, the patch radiators being arranged in an array and each patch radiator including at least one C-shaped slot.

[0033] Optionally, the antenna apparatus may comprise multiple patch radiators, each with at least one C-shaped slot. Arranging multiple such patch radiators allows for modular expansion of the antenna’s gain, directivity, and interference management capabilities across an entire array. It enables scalable performance improvements through array configurations, supporting advanced beamforming or high-capacity MIMO solutions.

[0034] According to a second aspect of this disclosure, a wireless communication device is provided. The wireless communication device comprises the antenna apparatus according to the first aspect or any one of the implementation forms of the first aspect.

[0035] Incorporating the above-described antenna apparatus into a wireless communication device ensures improved signal quality, reduced interference, and higher overall spectral efficiency for the end user. This disclosure delivers enhanced wireless functionality in a device by integrating an adaptable, interference-suppressing antenna system.

[0036] Implementation forms of the wireless communication device of the second aspect may correspond to the implementation forms of the antenna apparatus of the first aspect described above. The wireless communication device of the second aspect and its implementation forms achieve the same advantages and effects as described above for the antenna apparatus of the first aspect and its implementation forms.

[0037] It has to be noted that all devices, elements, units, and means described in the present application could be implemented in software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity that performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements or any kind of combination thereof.

[0038] BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above-described aspects and implementation forms will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which:

[0040] FIG. 1 shows an example of wireless communication setup in an MLO scenario;

[0041] FIG. 2 shows an overview of the Wi-Fi 5 GHz operating bands;

[0042] FIG. 3 shows an antenna apparatus according to an embodiment of the disclosure;

[0043] FIG. 4 shows two antenna apparatus designs according to embodiments of the disclosure;

[0044] FIG. 5 shows simulation results according to an embodiment of the disclosure;

[0045] FIG. 6 shows details of an antenna apparatus design according to an embodiment of the disclosure;

[0046] FIG. 7 shows simulation results according to an embodiment of the disclosure;

[0047] FIG. 8 shows details of an antenna apparatus design according to an embodiment of the disclosure;

[0048] FIG. 9 shows simulation results according to an embodiment of the disclosure; and

[0049] FIG. 10 shows exemplary wireless communication devices according to an embodiment of the disclosure.DETAILED DESCRIPTION OF EMBODIMENTS

[0050] Illustrative embodiments of an antenna apparatus and a corresponding wireless communication device are described with reference to the figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the application.

[0051] Moreover, an embodiment / example may refer to other embodiments / examples. For example, any description including but not limited to terminology, element, process, explanation, and / or technical advantage mentioned in one embodiment / example is applicative to the other embodiments / examples.

[0052] FIG. 1 illustrates a simplified wireless communication setup in an MLO scenario, involving a router, gateway, set-top-box (STB), or access point (API) and multiple stations (STA1 and STA2). The access point is equipped as an example with two antennas, ANTI and ANT2, which operate at different frequencies, denoted as fl and 12, respectively. ANTI transmits data to STA1 over frequency fl, while ANT2 transmits to STA2 over frequency 12.

[0053] ANT 1 (f 1 ) radiates the main, or co-band, signal intended for STA 1. This is denoted by Hl 1 • S 1 [ANT 1 ] , where Hl 1 encapsulates the AP ANTI gain at fl , along with co-band boresight performance. Simultaneously, ANT2 (operating at 12) can inadvertently couple unwanted energy into STAl’s receiver at fl . This is represented by H12-S2[ANT2], containing so-called “cross-band” boresight radiation.

[0054] The figure highlights a key challenge in MLO systems: ensuring that the transmission from ANT2 on frequency 12 does not interfere with the communication link between ANTI and STA1 operating on frequency fl (cross-band interference). This issue underlines the need for antennas capable of isolating co-band signals while rejecting cross-band interference, a feature central to the proposed solution.

[0055] FIG. 2 provides an overview of the Wi-Fi 5 GHz operating bands and the associated frequency interference issues as an example. The same antenna idea proposed here can be applied to filter out the interfering signals on Wi-Fi other bands, as well as the other wireless technologies. The diagram delineates the lower 5 GHz (L 5 GHz) band, ranging from 5.175 GHz to 5.335 GHz, and the upper 5 GHz (U 5 GHz) band, spanning 5.735 GHz to 5.835 GHz. These bands are subdivided into smaller channels used for various Wi-Fi applications, with bandwidths of 20 MHz, 40 MHz, 80 MHz, and 160 MHz.

[0056] L 5 GHz band includes channels like 36, 40, 44, and so on, up to channel 64. The region also indicates the presence of radar frequencies (e.g., between 5.250 GHz and 5.350 GHz) where Dynamic Frequency Selection (DFS) or Transmit Power Control (TPC) may be required to avoid interference. Notably, Wi-Fi modules may use band filters to minimize radar interference, but such filters can limit the flexibility and add costs to the system.

[0057] U 5 GHz Band includes channels such as 149, 153, 157, and up to channel 165. The figure highlights interference with vehicular communication systems like V2X (Vehicle-to-Everything) operating at adjacent frequencies (5.855-5.885 GHz). The proximity of these frequencies necessitates sharp filtering to prevent coexistence challenges.

[0058] The figure underscores the challenge of achieving sufficient isolation between coexisting bands while maintaining robust WiFi performance across the L and U 5 GHz bands. This application addresses these challenges by proposing an antenna design that incorporates filtering capabilities directly into the antenna structure, reducing dependency on external filters like BAW or SAW.FIG. 3 shows an example of embodiment of an antenna apparatus 300 for use in a wireless communication device. This approach aims to minimize interference from co-channel and adjacent-channel bands while maintaining high performance in multi-link operation scenarios.

[0059] In particular, FIG. 3 depicts the antenna apparatus 300 including a patch radiator 301 with at least one C-shaped slot 302. This design enables selective rejection of signals within specific frequency bands while allowing the primary frequency range to operate effectively. The embodiments described below correspond to the features claimed in the patent.

[0060] The patch radiator 301 is designed to operate in a first frequency range. At least one C-shaped slot 302 formed within or on the patch radiator 301 is arranged to selectively reject signals in at least one second frequency band that overlaps or lies within the first frequency range.

[0061] According to an embodiment of this disclosure, the dimensions of the C-shaped slot 302 are designed to determine the center frequency of the second frequency band to be rejected. The rejection characteristics can be finely tuned based on the slot's physical parameters.

[0062] Possibly, the position and orientation of the C-shaped slot 302 relative to the feed point of the patch radiator 301 are configured to adjust the bandwidth of the rejection band. This feature allows customization of the rejection profile for specific applications or frequency environments.

[0063] According to another embodiment of this disclosure, the C-shaped slot 302 may include a pin diode, enabling or disabling the slot for example with short-circuit and open-circuit connection at the center of the slot, enabling or disabling rejection of signals in the second frequency band. This provides dynamic control over the antenna's operating characteristics, enabling flexible adaptation to varying operational requirements.

[0064] The antenna apparatus 300 can be fed using various methods, including: capacitive coupling, microstrip feeding, or coaxial feeding.

[0065] For instance, the antenna apparatus 300 may have a single-feed configuration with a single feed point, or a dual-feed setup with a first feed port for radiation of one polarization (e.g., vertical) and a second feed port for radiation of an orthogonal polarization (e.g., horizontal).

[0066] The C-shaped slot 302 is further configured to reduce boresight gain in the second frequency band, enhancing port-to-port isolation. This is particularly beneficial for multi-link operations, as it minimizes interference between transmit and receive signals (Tx-Rx and Rx-Tx) and supports coexistence with other technologies such as IMT 5G, CV2X, and radar systems.

[0067] Optionally, the antenna apparatus 300 can include a plurality of C-shaped slots 302, each independently configured to reject a specific frequency band. This allows multi-band filtering capabilities, enabling operation across diverse frequency environments.

[0068] The patch radiator 301 may have a substantially square shape with its side length tailored to suit the intended first frequency range:

[0069] • Millimeter- wave frequencies (40-60 GHz): Side length in the range of a few millimeters.

[0070] • Wi-Fi bands (around 5-6 GHz): Side length in the range of tens of millimeters.

[0071] • Sub-GHz frequencies (below 1 GHz): Side length in the range of tens of centimeters.The C-shaped slot 302 may have a radius ranging from 10% to 30% of the patch radiator's side length. Defining the slot’s radius as a fraction (10%— 30%) of the patch side length ensures the notch filter effect scales appropriately with the patch dimension, preserving rejection characteristics. This configuration provides design parameters for the C-shaped slot that are proportionally scaled with patch size, ensuring consistent performance across varied frequency ranges.

[0072] Referring to FIG. 4, the antenna apparatus 300 is depicted in three distinct views, demonstrating variations in feed setups and structural configurations of the antenna with integrated C-shaped slots. These configurations highlight both single-feed and dual- feed operation and include a side view of the antenna's layered design.

[0073] In one embodiment as shown in FIG. 4(a), the antenna apparatus 300 may have a single-feed configuration with a single feed point 303. FIG. 4(a) shows a top view of a patch radiator 301 features three C-shaped slots 302 arranged to target specific rejection bands while maintaining operation within the first frequency range (e.g., Wi-Fi 5 GHz or 6 GHz).

[0074] The patch radiator 301 is shown as a square or rectangular element with dimensions (length) and Wp (width). Two C-shaped slots 302 are integrated into the radiator. These slots are positioned and dimensioned with a specific gap and radius to achieve desired band-rejection properties: Gapl , Gap2, and Gap3 define the spacing of the slots from their respective centers, allowing independent operation for targeting distinct frequency bands. The configuration allows for flexible adjustment of the rejection bandwidth and center frequencies. The slots operate almost independently, ensuring selective filtering of undesired signals from co- and adjacent bands, such as IMT 5G, radar, or other wireless technologies.

[0075] In this embodiment, the feed arrangement is a single-feed capacitive coupling setup, positioned centrally below the patch radiator. This setup simplifies the antenna design while maintaining wideband performance and providing rejection in undesired adjacent or overlapping frequency bands.

[0076] The single-feed design is optimized for broad coverage of the Wi-Fi spectrum and supports multi-band rejection using the C-shaped slots.

[0077] In another embodiment as shown in FIG. 4(b), the antenna apparatus 300 may have a dual-feed configuration designed for enhanced performance in dual-band Wi-Fi operation. This dual-feed setup comprises a first feed port 303 to allow radiation of a first polarization and a second feed port 304 to allow radiation of a second polarization. FIG. 4(b) shows a top view of the patch radiator 301. The patch radiator 301 includes two C-shaped slots 302 strategically positioned to achieve band-specific rejection for each feed port.

[0078] The dual-feed structure allows independent feeds for vertical and horizontal polarizations or different frequency bands. This configuration is particularly useful in multi-band, multi-user scenarios where simultaneous transmission and reception are required across different portions of the Wi-Fi spectrum.

[0079] The patch radiator 301 may be configured such that the first feed port 303 operates primarily in a lower portion of at least one Wi-Fi frequency band while substantially rejecting signals in an upper portion of said band, and such that the second feed port 304 operates primarily in the upper portion of the same Wi-Fi frequency band while substantially rejecting signals in the lower portion thereof. This implementation ensures that each port operates efficiently within its allocated spectrum, avoiding interference and maintaining signal integrity.For instance, Portl operates predominantly in the L5 GHz band while incorporating a filtering mechanism to reject signals in the U5 GHz band. Port2 operates predominantly in the U5 GHz band while filtering out the L5 GHz band.

[0080] Each C-shaped slot 302 is strategically oriented and positioned relative to the respective feed ports to target its specific rejection band. This design enhances the isolation between the two feed ports, ensuring minimal coupling and interference.

[0081] The placement and orientation of the two C-shaped slots 302 are optimized to maximize isolation between the ports. This placement ensures effective suppression of cross-band signals and reduces boresight gain, enhancing the antenna's suitability for advanced Wi-Fi and co-existence scenarios (e.g., with 5G, radar, or other wireless technologies).

[0082] The dual-feed configuration allows simultaneous operation in both L5 GHz and U5 GHz bands while maintaining high port-to-port isolation. This feature is critical for APs that need to maximize MLO efficiency, ensuring robust communication with multiple STAs.

[0083] FIG. 4(c) provides a side view of the antenna apparatus 300, showing its layered structure. The design features a coupling feeding system and two substrates (e.g., FR4). The patch radiator 301 and C-shaped slots 302 are fabricated on the upper layer (with thickness d I ). and the bottom layer (with thickness d2) is a base layer forming a ground plane for the antenna.

[0084] The gap between the two substrates has a height h. This gap may be maintained by an RF spring, which is flexible and can be adjusted in future designs to accommodate different requirements. The gap allows for proper coupling between the feed structure and the patch radiator 301. The capacitive feed structure is positioned below the patch radiator and interfaces with the ground plane.

[0085] The side view highlights the simplicity of the capacitive feed arrangement, which can be replaced with a microstrip or coaxial feed depending on design requirements. The design supports integration into compact wireless devices such as Wi-Fi routers, ensuring compatibility with existing manufacturing processes.

[0086] It may be understood that the patch radiator 301 shown in FIG. 4(b) also has the similar dimensions parameters as shown in FIG. 4(a). For instance, dimensions Lp, Wp, h, dl, d2. and slot parameters are configurable to support multiple frequency bands, including Wi-Fi 5 GHz and 6 GHz bands.

[0087] In both single-feed and dual-feed setups, the C-shaped slots 302 are positioned and oriented to achieve selective filtering. The placement of the slots ensures minimal impact on the antenna's radiation performance in the desired frequency range.

[0088] The slots' dimensions and gaps (e.g., Gapl, Gap2, Gap3) allow flexible tuning of the rejection bands, supporting wide or narrow filtering depending on application requirements.

[0089] The antenna is scalable for different operational ranges, including mmWave, Wi-Fi (5 GHz, 6 GHz), and sub-GHz frequencies, with geometric parameters (e.g., Lp, Wp, h, dl, d2) configurable to meet specific requirements.

[0090] FIG. 5 illustrates the simulated frequency response of the single-feed setup antennas with integrated C-shaped slots. The results highlight the antenna's performance in selectively rejecting undesired signals within the Wi-Fi frequency spectrum.

[0091] As shown in FIG. 5, one example of antenna design with two integrated C-shaped slots, and one example of antenna design with one integrated C-shaped slot, are compared.The top graph of FIG. 5 demonstrates the antenna's rejection performance for the U5 GHz band. A deep notch in the frequency response is observed around 5.8 GHz, indicating the suppression of signals in the upper portion of the 5 GHz band. That is, the integrated C-shaped slots create a notch with a rejection of at least 10 dB in the U5 GHz band. This ensures that signals in the U5 GHz band are significantly attenuated, while the antenna maintains operation in the L5 GHz band without degradation.

[0092] This configuration is suitable for scenarios where interference in the U5 GHz band must be mitigated, such as in environments with overlapping channels or coexisting wireless systems like 5G or radar.

[0093] The bottom graph highlights the antenna's rejection performance for the L5 GHz band. A notch is observed around 5.2 GHz, where the frequency response shows a rejection of at least 10 dB.

[0094] The rejection ensures that undesired signals in the L5 GHz band are suppressed, allowing the antenna to operate efficiently in the U5 GHz band. The design achieves this selective filtering without compromising the wideband nature of the antenna outside the rejection band.

[0095] This configuration is optimal for applications that require operation in the U5 GHz band while avoiding interference from signals in the L5 GHz band.

[0096] FIG. 5 validates the performance of the single-feed antenna with integrated C-shaped slots, where both rejection notches exhibit a depth of at least 10 dB, effectively isolating the desired operating band from the rejected band. It can be seen from the figure, the bandwidth of the rejection bands can be tuned by adjusting the size, position, and orientation of the C-shaped slots. Further, outside the rejection bands, the antenna demonstrates a smooth and consistent frequency response, ensuring efficient operation in the desired bands.

[0097] The C-shaped slots provide band-rejection functionality without additional external components, maintaining the simplicity and cost-effectiveness of the single-feed antenna design.

[0098] FIG. 6 provides an in-depth view of the application of C-shaped slots on a single-feed antenna apparatus 300 (e.g., Design 1 shown in FIG. 4(a)), demonstrating their ability to create notch bands for rejecting unwanted frequencies. Additionally, it illustrates the surface current distributions of the original patch antenna at its resonance frequencies, showcasing how the slots affect the antenna's current patterns and performance.

[0099] As shown in FIG. 6(a), the patch radiator 301 integrates multiple C-shaped slots 302 positioned to selectively reject signals from coexisting bands such as:

[0100] • IMT 5G: Suppression of interference from cellular signals.

[0101] • C-V2X: Mitigation of interference from automotive communication systems.

[0102] • Wi-Fi Coexistence: Filtering adjacent Wi-Fi bands to enhance performance in the operational band.

[0103] The illustration in FIG. 6(a) highlights the geometrical parameters of the slots: R1 , R2, and R3 : radii of the slots, determining the center frequencies of the rejected bands, and Gapl, Gap2, and Gap3: the distances between the slot elements and their respective centers, which affect the bandwidth and rejection depth.

[0104] A single-feed capacitive coupling structure is used to excite the patch radiator 301. The integration of slots allows the patch to maintain wideband operation while selectively attenuating undesired signals in specific frequency bands.The configuration effectively introduces notch bands at targeted frequencies. These rejection bands ensure that the antenna can operate in its desired frequency range while suppressing interference from overlapping and adjacent technologies.

[0105] FIG. 6(b) shows surface current distributions of the original patch antenna and the proposed antenna apparatus at their respective resonance frequency.

[0106] It can be seen that the surface current of the original patch is uniformly distributed, resulting in a broad radiation pattern and wideband coverage. For antenna apparatus with slots, the C-shaped slots disrupt the current flow at their respective resonance frequencies, creating localized high-intensity regions. This disruption reduces radiation at the rejected frequencies, forming notch bands in the antenna's frequency response.

[0107] Therefore, the integration of slots allows the antenna apparatus to selectively filter signals from different frequency bands (e.g., IMT 5G, C-V2X, Wi-Fi coexistence) without the need for external components.

[0108] FIG. 7 demonstrates the performance and radiation patterns of a single-feed triple-notched band antenna (as shown in FIG.

[0109] 6(a)). This antenna utilizes integrated C-shaped slots for precise control over the rejection bands and their bandwidths.

[0110] FIG. 7(a) shows the realized gain of the antenna across the frequency spectrum, highlighting three distinct notched bands:

[0111] • 5G LampSite Rejection (wide band): Centered around 5.15 GHz, this notch is designed to suppress interference from cellular 5G signals in LampSite environments.

[0112] • Wi-Fi UNII-2C Rejection (sharp band): Centered around 5.35 GHz, this sharp notch targets interference from specific Wi-Fi sub-bands in the UNII-2C range.

[0113] • C-V2X Rejection (wide band): Centered around 5.89 GHz, this notch mitigates interference from Cellular Vehicle- to-Everything (C-V2X) communication systems.

[0114] Each notch achieves significant gain reduction (~25 dB) within its respective frequency range, effectively isolating the desired operational band. The slot size determines the center frequency of the notched bands, allowing precise tuning for specific applications. The slot location relative to the feed point adjusts the bandwidth of the notches, providing flexibility for wide or narrow rejection bands as needed.

[0115] FIG. 7(b) shows far-field radiation patterns of antenna with slots or without slots for each operating frequency.

[0116] It can be seen that the radiation pattern for antenna with slots exhibits a significant reduction in boresight gain within the rejected band. This reduction enhances port-to-port isolation and prevents cross-band interference, which is critical for coexisting wireless technologies. Without slots, the radiation patterns exhibit high boresight gain, leading to unwanted interference.

[0117] The inclusion of slots selectively suppresses these gains, improving overall system performance by isolating desired bands from adjacent-band signals. The notched bands' center frequencies are precisely controlled by the slot sizes (e.g., radius or width of the C-shaped slots). The antenna effectively reduces cross-band boresight gain by ~25 dB at the rejected frequencies, a feature highly desirable for multi-link operation where interference between bands must be minimized. The ability to reject 5G, Wi-Fi, and C-V2X bands ensures compatibility with diverse wireless systems, making the antenna suitable for advanced communication environments such as smart homes, automotive systems, and industrial loT.FIG. 8 shows exemplary dual-feed antenna designs (e.g., Design 2 shown in FIG. 4(b)) according to this disclosure, and the performance of the dual-feed single-notched band antenna. FIG. 8 showcases the ability to isolate signals between two frequency bands in a Wi-Fi dual-band operation. The antenna is designed such that each feed port operates within a distinct portion of the 5 GHz Wi-Fi spectrum while effectively rejecting interference from the adjacent band.

[0118] In this design, each port (e.g., 303, 304) is independently fed, with the design enabling separation of vertical (V-pol) and horizontal (H-pol) polarizations or distinct frequency bands. For instance, the configuration supports simultaneous operation in L5 GHz and U5 GHz bands, making it ideal for dual-band Wi-Fi applications.

[0119] In one example, Portl (303) operates primarily in the L5 GHz band (e.g., 5.15-5.35 GHz). This antenna design integrates a notched filter to reject signals from the U5 GHz band (e.g., 5.47-5.85 GHz). Such design achieves at least 10 dB suppression of U5 GHz signals, ensuring minimal interference.

[0120] Port2 (304) operates primarily in the U5 GHz band (e.g., 5.47-5.85 GHz). The antenna design also integrates a notched filter to reject signals from the L5 GHz band (e.g., 5.15-5.35 GHz). Similarly, it provides at least 10 dB suppression of L5 GHz signals.

[0121] The dual-feed design ensures high isolation between the ports by rejecting signals from the other band's operational range. This isolation minimizes cross-talk and improves the overall performance of multi-band systems, particularly in environments with overlapping Wi-Fi channels. By isolating L5 GHz and U5 GHz signals, the antenna reduces interference and ensures robust communication in multi-link Wi-Fi setups, where multiple bands operate simultaneously. This feature is particularly important for APs communicating with multiple STAs using different frequency bands.

[0122] FIG. 9 illustrates the impact of the designed antenna on the reflection coefficient Sil, focusing on the cross-band reflection coefficient SI 1 cross-band and the co-band reflection coefficient SI lco-band. This design aims to reduce the coupled power between AP ports, which is essential for improving the performance of multi-link operations where multiple bands are utilized.

[0123] The graph shows an increase in the reflection coefficient Sil cross-band at the notched band frequencies: around 5.17 GHz, which corresponds to the rejection band for the L5 GHz band (5GL), and around 5.73 GHz, which corresponds to the rejection band for the U5 GHz band (5GH). This increase indicates effective rejection of signals outside the desired operational bands, minimizing the cross-band coupling and interference.

[0124] The antenna maintains a low reflection coefficient SI lco-band within the desired operational bands (e.g., 5GL for the 5GL filter antenna and 5GH for the 5GH filter antenna). This ensures efficient radiation and minimal power loss in the intended frequency band, critical for reliable communication.

[0125] It can be clearly seen that the original patch antenna lacks the notched bands and shows a continuous Sil response with no significant cross-band rejection. The filter antennas demonstrate improved performance by introducing notched bands that increase Sil cross-band, reducing interference from adjacent frequency bands.

[0126] By increasing SI 1 cross-band, the antenna reflects unwanted signals back to the source rather than allowing them to couple to the other AP port. This together with a low transmittance coefficient S21 , results in a lower coupling between two AP ports, which minimizes interference and enhances multi-link operation.In MLO scenariors, an STA transmitting to an AP requires clear and isolated channels. The improved Sllcross-bmd reduces interference, ensuring better channel quality for STA transmissions to AP receivers.

[0127] The selective rejection of cross-band signals allows the AP to efficiently operate in both the L5 GHz and U5 GHz bands, without mutual interference between the ports.

[0128] The design ensures that each port operates independently within its designated band, supporting simultaneous communication across multiple bands. Lower coupled power between ports translates to less interference, reduced noise, and improved throughput in multi-link Wi-Fi scenarios. The increased Sllcross-band also helps mitigate interference from coexisting technologies such as 5G or radar systems, ensuring robust Wi-Fi performance.

[0129] In a further embodiment, a wireless communication device as shown in FIG. 10, such as a Wi-Fi access point, router, or client station, is provided with the antenna apparatus 300 described in the foregoing embodiments. The device may include: a housing or chassis, the antenna apparatus 300 described in the foregoing embodiments, radio transceiver circuitry, power and control modules, and other necessary components.

[0130] To summarize, embodiments of this disclosure present a versatile and high-performance patch antenna design with integrated C-shaped slots and a robust coupling feeding system. This innovative approach addresses key challenges in modem wireless communication systems, particularly in multi-link and multi-band Wi-Fi applications. The following key aspects summarize the disclosure:

[0131] The incorporation of C-shaped slots enables precise filtering of undesired frequency bands, reducing interference from co- and adjacent-band signals such as 5G, C-V2X, and radar. These slots are cost-effective, seamlessly integrated into the patch radiator, and configurable for various frequency bands.

[0132] The proposed patch antenna supports wideband performance, covering critical Wi-Fi frequency ranges (e.g., 5 GHz and extendable to 6 GHz or mmWave bands), while achieving high isolation between feed ports. Cross-band suppression improves port-to-port isolation, ensuring robust communication in multi-link scenarios.

[0133] Optionally, the at least one C-shaped slot may comprise a pin diode configured to enable or disable rejection of signals in the at least one second frequency band. Using a pin diode placed in or around the C-shaped slot enables an active mechanism to either introduce or remove the notch filter behavior in real time, benefiting scenarios where multiple frequency bands are used. It provides reconfigurability of the notch, enabling dynamic switching of the rejection band on or off, thus adapting to changing operational requirements.

[0134] The coupling feeding system, including the RF spring and coupling strip, provides wideband, low-loss performance and mechanical robustness. The flexibility of the RF spring allows adaptation to future designs, ensuring long-term relevance and scalability.

[0135] The design is adaptable to multiple configurations, including single-feed, dual-feed, and array setups, supporting advanced beamforming and high-gain applications. The materials and structure (e.g., FR4 substrates, adjustable gap) are cost-efficient and compatible with standard manufacturing processes.By increasing cross-band reflection and maintaining low co-band reflection, the antenna reduces coupled power between ports, ensuring high channel quality for both Tx and Rx in multi-link environments. This makes the antenna particularly suitable for next-generation wireless devices, including Wi-Fi routers, loT systems, and automotive communication platforms.

[0136] The present disclosure has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed embodiments of the disclosure, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation. Furthermore, the word “coupled” implies that the elements may be directly connected together or may be coupled through one or more intervening elements. Moreover, the disclosure with regard to any of the aspects is also relevant with regard to the other aspects of the disclosure.

[0137] Although the disclosure has been illustrated and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In addition, while a particular feature of this disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.

[0138] In some embodiments, the present disclosure relates to an antenna structure configured for multi-band operation. The antenna may be used in any wireless communication device, such as a Wi-Fi access point or router, that includes radio circuitry for transmitting / receiving signals.

[0139] While the present disclosure has been described primarily with respect to antenna structures and the associated hardware, one skilled in the art will appreciate that various aspects of the disclosure may be implemented, controlled, or monitored using software, firmware, or a combination of hardware and software. In particular, software algorithms and computer-readable media may be employed to manage or optimize certain functionalities (e.g., calibration, tuning, or adaptation) of the antenna system. The disclosure is not limited to any specific software architecture or programming language. Where applicable, software instructions can be stored in or on a computer-readable medium, such as a ROM, PROM, EPROM, EEPROM, Flash memory, or any other form of storage device, and executed by one or more processors, controllers, or DSPs (digital signal processors). Likewise, certain embodiments may rely purely on hardware implementations without separate software control, and nothing herein shall be construed to limit the scope of the disclosure to any particular form of hardware, software, or firmware.

Claims

CLAIMS1. An antenna apparatus (300) for use in a wireless communication device, comprising:a patch radiator (301) configured to operate in a first frequency range; andat least one C-shaped slot (302) formed on or within the patch radiator (301 ),wherein said at least one C-shaped slot (302) is arranged to selectively reject signals in at least one second frequency band within or overlapping the first frequency range.

2. The antenna apparatus (300) according to claim 1 , wherein the dimensions of the at least one C-shaped slot (302) are selected to define a center frequency of the second frequency band.

3. The antenna apparatus (300) according to claim 2, wherein the position and / or the orientation of the at least one C-shaped slot (302) relative to a feed point of the patch radiator (301 ) is configured to adjust a bandwidth of the second frequency band.

4. The antenna apparatus (300) according to any preceding claims, wherein the at least one C-shaped slot (302) comprises a pin diode configured to enable or disable rejection of signals in the at least one second frequency band.

5. The antenna apparatus (300) according to any preceding claims, further comprising a feed arrangement configured to operate in the first frequency range, wherein the feed arrangement comprises at least one of the following: capacitive coupling, microstrip feed, coaxial feed.

6. The antenna apparatus (300) according to claim 5, wherein the feed arrangement is configured as a single-feed comprising a single feed point.

7. The antenna apparatus (300) according to claim 5, wherein the feed arrangement is configured as a dual-feed setup comprising a first feed port to allow radiation of a first polarization and a second feed port to allow radiation of a second polarization.

8. The antenna apparatus (300) according to claim 7, wherein the patch radiator (301) is configured such that the first feed port operates primarily in a lower portion of at least one Wi-Fi frequency band while substantially rejecting signals in an upper portion of said band, and such that the second feed port operates primarily in the upper portion of the same Wi-Fi frequency band while substantially rejecting signals in the lower portion thereof.

9. The antenna apparatus (300) according to any preceding claims, wherein the at least one C-shaped slot (302) is configured to reduce boresight gain at the second frequency band, thereby enhancing port-to-port isolation for multi-link operation.

10. The antenna apparatus (300) according to any preceding claims, wherein the at least one C-shaped slot (302) comprises a plurality of C-shaped slots (302), each C-shaped slot (302) being independently configured to reject a respective second frequency band.

11. The antenna apparatus (300) according to any preceding claims, wherein the patch radiator (301) has a substantially square shape with a side length selected to provide radiation coverage within the first frequency range, the side length being one of the following:on the order of a few millimeters if the first frequency range is between about 40 GHz and 60 GHz,on the order of tens of millimeters if the first frequency range is in a Wi-Fi band around 5 GHz or 6 GHz, on the order of tens of centimeters if the first frequency range is below about 1 GHz.

12. The antenna apparatus (300) according to claim 11, wherein the C-shaped slot (302) has a radius of about 10% to about 30% of the side length of the patch radiator (301).

13. The antenna apparatus (300) according to any preceding claims, further comprising a plurality of the patch radiator (301), the patch radiators (301) being arranged in an array and each patch radiator (301) including at least one C-shaped slot (302).

14. A wireless communication device comprising:the antenna apparatus (300) according to any preceding claims.

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