Microstrip antenna with impedance matching bandpass filter

Abstract

A microstrip antenna for operating within an operating frequency range. The microstrip antenna includes an antenna structure printed on a substrate within a compact area. The microstrip antenna also includes a feedback structure printed on the substrate within the compact area, wherein the feedback structure is configured to function as an impedance matched bandpass filter having a passband defining the operating frequency range. Due to the integrated bandpass filter, the microstrip antenna provides high efficiency, low loss and compact size, suitable for ultra-wideband wireless networks.

Description

Technical Field

[0001] The present disclosure relates generally to the field of antenna systems and wireless communication technology, and more particularly to a microstrip antenna with an impedance-matched bandpass filter for use in ultra-wideband wireless networks. Background Art

[0002] With the development of connected vehicles such as autonomous vehicles (e.g., self-driving cars) or semi-autonomous vehicles, the demand for complex interconnected and machine-to-machine networks is steadily rising. In addition, there is a trend to integrate user devices (e.g., smartphones) with the entertainment and safety systems of customer cars. As a result, there is an increasing demand for higher data transmission via wireless networks, which in turn requires spatially dense integration of antennas in vehicles (e.g., autonomous and customer vehicles). However, the limitation of available space and the increase in the number of antennas (e.g., integrated antennas), as well as electromagnetic coupling between antennas, pose challenges for the efficient use of available space. For example, an antenna operating in a frequency band interferes with an adjacent antenna operating in an adjacent frequency band by absorbing frequencies from the adjacent frequency band (due to limited space and electromagnetic coupling), thereby resulting in a decrease in the efficiency of the adjacent antenna.

[0003] At present, some attempts have been made to decouple antennas (i.e., integrated antennas) by using conventional distributed filters or conventional lumped filters between antennas. Both conventional distributed filters and lumped filters have their own characteristics and limitations. Conventional distributed filters use the electromagnetic properties of waves (e.g., working waves) to produce inductive or capacitive effects within a certain bandwidth. This is why conventional distributed filters are comparable in size to the working wave (or wavelength). Conventional distributed filters exhibit some low losses (or low loss characteristics), but require the use of a relatively large area. Conventional distributed filters, for example, conventional distributed bandpass filters can have a center frequency of 5 gigahertz (GHz) and a size of approximately 14 mm×14 mm. Therefore, a wireless network including a conventional distributed filter, called a distributed bandpass matching network, exhibits some low losses (e.g., insertion loss and return loss), but has a limited bandwidth and a larger size to be used. Therefore, the low loss advantage of conventional distributed filters comes at the expense of large size. Another way to decouple antennas (i.e., integrated antennas) is to use conventional lumped filters. Conventional lumped filters use inductive or capacitive components, each of which is much smaller than the working wavelength. Conventional lumped filters are usually employed in a compact form by using typical surface mount device (SMD) filters. A surface mount device (SMD) is an electronic component, also known as an integrated passive device (IPD) or an integrated passive component (IPC) or an embedded passive component (EPC), in which a resistor (R), a capacitor (C), an inductor (L) or a coil or choke, a microstrip line, an impedance matching element, a balun (i.e. a balanced-unbalanced converter) or any combination of said components are integrated on the same package or on the same substrate. Thus, conventional lumped surface mount device (SMD) filters can be implemented on relatively small structures and can therefore be very compact. However, conventional lumped SMD filters are expensive (roughly 20 cents to 30 cents) and have significant losses (e.g. 1 dB to 2 dB) during operation compared to conventional distributed filters for mass production. Conventional lumped SMD filters have a fixed frequency range and have poor reliability due to aging of SMD components. Furthermore, if conventional lumped SMD filters are used as integrated passive device (IPD) filters, they have the limitation of being inflexible in filter design.Since each component such as the inductor (L), capacitor (C), resistor (R), etc. is integrated in one package in the case of the conventional IPD filter, the characteristics of the conventional IPD filter are defined before and after production, and the filter design cannot be changed. Therefore, in applications requiring low loss and high efficiency, the conventional lumped SMD filter is not the first choice. In other words, the lumped matching network including the conventional lumped SMD filter is compact, but brings significant losses (such as insertion loss and return loss) to the network. Therefore, there is a technical problem of an inefficient antenna, which exhibits reduced efficiency, significant losses (i.e., insertion loss and return loss), and has a large size comparable to the operating wavelength, and therefore, the conventional antenna is not suitable for broadband or ultra-wideband wireless networks.

[0004] Therefore, based on the above discussion, there is a need to overcome the above-mentioned disadvantages associated with conventional antennas. Summary of the invention

[0005] The present disclosure seeks to provide a microstrip antenna with an integrated bandpass filter for use in ultra-wideband wireless networks. The present disclosure seeks to provide a solution to the existing problems of inefficient antennas, which exhibit significant losses (i.e., insertion loss and return loss) and have large dimensions comparable to the operating wavelength, and are not suitable for use in broadband or ultra-wideband wireless networks. The purpose of the present disclosure is to provide a solution that at least partially overcomes the problems encountered in the prior art and to provide an improved antenna with an integrated bandpass filter, which has improved efficiency, low losses, and compact dimensions, and is suitable for use in ultra-wideband wireless networks.

[0006] The objects of the present disclosure are achieved by the solutions provided in the attached independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.

[0007] In one aspect, the present disclosure provides a microstrip antenna for operating within an operating frequency range, the microstrip antenna comprising an antenna structure printed within a compact area on a substrate. The microstrip antenna also comprises a feedback structure printed within a compact area on the substrate, wherein the feedback structure is configured to function as an impedance matched bandpass filter having a passband defining the operating frequency range.

[0008] The disclosed microstrip antenna creates a matching network with a bandpass characteristic. The disclosed microstrip antenna integrates a bandpass filter into the antenna structure. By using a bandpass filter as part of the antenna structure, it is possible to create a fairly compact design. Compared with a conventional distributed filter, the bandpass filter has the advantages of a distributed filter while having a relatively small size. In this way, the disclosed microstrip antenna has significantly low losses and a compact design. The disclosed microstrip antenna reduces electromagnetic coupling between integrated antennas by using a bandpass filter, thereby reducing electromagnetic interference between integrated antennas. In addition, compared with conventional lumped SMD filters, the disclosed microstrip antenna significantly reduces the effects of SMD component aging and improves reliability. In addition, the disclosed microstrip antenna does not require additional space on the main printed circuit board (PCB) and has no negative impact on antenna efficiency compared with conventional lumped SMD filters. Therefore, due to the integrated bandpass filter, the disclosed microstrip antenna provides high efficiency, low loss and compact size, suitable for use in ultra-wideband wireless networks.

[0009] In one implementation, the feedback structure includes two stub feedback lines arranged on either side of a feed point of the antenna structure.

[0010] The two stub feedback lines are used to create a bandpass filter, and the created bandpass filter decouples nearby antennas operating in adjacent frequency bands, thereby reducing electromagnetic interference between the disclosed microstrip antenna and the nearby antennas. The bandpass filter is created by tuning the impedance of the disclosed microstrip antenna by changing the size of the disclosed microstrip antenna and the size of the two stub feedback lines.

[0011] In another implementation, each of the two stub feedback lines terminates close to a feed point of the antenna structure.

[0012] The two stub feed lines terminate close to the feed point of the antenna structure, thus allowing the microstrip antenna to have a more compact design.

[0013] In a further implementation, each of the two stub feedback lines extends along an edge of the compact area.

[0014] Each of the two stub feedback lines acts as a compact bandpass and matching filter, which is integrated into the disclosed microstrip antenna on the same printed circuit board (PCB). This enables the microstrip antenna to have a more compact design.

[0015] In a further implementation, the compact area is substantially rectangular or square, with a height and a width each in the range of 15 mm to 20 mm.

[0016] Since both the antenna structure and the feedback structure are fabricated in a compact area on the substrate, this enables the microstrip antenna to be more compact in size and thus also exhibit low losses during operation.

[0017] In a further implementation, the antenna structure includes a monopole antenna.

[0018] Two stub feedback lines create a bandpass filter that can be used with monopole antennas for automotive applications.

[0019] In a further implementation, the antenna structure includes a dipole antenna.

[0020] In this case, the feedback structure includes four feedback lines because each monopole element of the dipole antenna requires two feedback lines to create a bandpass filter for itself.

[0021] In a further implementation, the operating frequency range is from about 3.3 GHz to about 5.0 GHz.

[0022] The disclosed microstrip antenna can be used at microwave frequencies, particularly for C-band applications, such as automotive applications.

[0023] It should be noted that all devices, elements, circuits, units and methods described in this application can be implemented in software or hardware elements or any type of combination thereof. All steps performed by various entities described in this application and the functions to be performed by various entities described are intended to refer to the corresponding entities for performing the corresponding steps and functions. Although in the description of the following specific embodiments, the specific functions or steps performed by external entities are not reflected in the description of the specific detailed elements of the entities performing the specific steps or functions, it should be clear to the technician that these methods and functions can be implemented by corresponding hardware or software elements or any combination thereof. It is understandable that the features of the present disclosure are easy to be combined in various combinations without departing from the scope of the present disclosure defined by the appended claims.

[0024] Other aspects, advantages, features and objects of the present disclosure will become apparent from the accompanying drawings and detailed description of illustrative implementations interpreted in conjunction with the following appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] When read in conjunction with the accompanying drawings, the above summary of the invention and the following detailed description of illustrative embodiments may be better understood. In order to illustrate the present disclosure, exemplary structures of the present disclosure are shown in the accompanying drawings. However, the present disclosure is not limited to the specific methods and tools disclosed herein. In addition, it should be understood by those skilled in the art that the accompanying drawings are not drawn to scale. Where possible, identical elements are represented by identical numerals.

[0026] Embodiments of the present disclosure will now be described by way of example only with reference to the following figures, in which:

[0027] Figure 1 A microstrip antenna according to an embodiment of the present disclosure is shown;

[0028] Figure 2 shows the bandpass characteristics of the microstrip antenna according to an embodiment of the present disclosure;

[0029] Figures 3A to 3B shows the transition from band-stop to band-pass in the Smith chart of a microstrip antenna according to an embodiment of the present disclosure;

[0030] Figures 4A to 4B The conversion of the amplitude-frequency of the microstrip antenna from band-stop to band-pass according to an embodiment of the present disclosure is shown;

[0031] Figure 5A shows the frequency response of the feedback stub of the microstrip antenna according to an embodiment of the present disclosure;

[0032] Figure 5B The bandpass characteristics of the microstrip antenna according to the embodiment of the present disclosure are shown.

[0033] In the drawings, underlined numbers are used to indicate the item in which the underlined number is located or an item adjacent to the underlined number. Non-underlined numbers are associated with the item identified by the line associating the non-underlined number with the item. When a number is not underlined and has an associated arrow, the non-underlined number is used to identify the general item to which the arrow points. DETAILED DESCRIPTION

[0034] The following detailed description describes embodiments of the present disclosure and ways in which these embodiments can be implemented. Although some modes of implementing the present disclosure have been disclosed, those skilled in the art will recognize that there may be other embodiments for implementing or practicing the present disclosure.

[0035] Figure 1 FIG. 1 shows a microstrip antenna according to an embodiment of the present disclosure. Figure 1 , a microstrip antenna 100 is shown. The microstrip antenna 100 includes an antenna structure 102, a substrate 104, a first short stub feedback line 106A, a second short stub feedback line 106B, a feed point 108, and an electrical ground 110. The feed point 108 and the electrical ground 110 are represented by dashed portions, which are only used for illustration purposes and do not form part of the circuit.

[0036] The microstrip antenna 100 is used to operate in an operating frequency range (e.g., 3.3 GHz to 5 GHz). The microstrip antenna 100 is used for C-band applications (i.e., 3.3 GHz to 5 GHz), such as automotive applications. The microstrip antenna 100 may also be referred to as a radiating device. An array of such microstrip antennas or one or more microstrip antennas may be used in a wireless communication system. Examples of such wireless communication systems include, but are not limited to, active base station antenna systems, automotive antenna systems (AAS), base stations (e.g., evolved NodeB (eNB), next generation NodeB (gNB), etc.), repeater devices, user end devices, and other customized communication hardware.

[0037] The microstrip antenna 100 includes an antenna structure 102 printed in a compact area on a substrate 104. The microstrip antenna 100 also includes a feedback structure printed in a compact area on the substrate 104, wherein the feedback structure is configured to act as an impedance matched bandpass filter having a passband defining an operating frequency range. The microstrip antenna 100 includes the antenna structure 102 and the feedback structure on the substrate 104, thereby enabling a more compact design. The feedback structure acts as a bandpass filter, and thus, the microstrip antenna 100 reduces the impact on nearby antennas operating on adjacent frequency bands, thereby providing high efficiency. The antenna structure 102 and the feedback structure are composed of metal (or multiple metals), such as copper metal. Figure 2 The figures describe the passband characteristics of the microstrip antenna 100 in detail.

[0038] According to an embodiment, the feedback structure includes two short stub feedback lines arranged on both sides of the feed point 108 of the antenna structure 102. The feedback structure is implemented by using two short stub feedback lines represented as the first short stub feedback line 106A and the second short stub feedback line 106B. The first short stub feedback line 106A is used as a filter 1 and is arranged on the right side of the antenna structure 102. The second short stub feedback line 106B is used as a filter 2 and is arranged on the left side of the antenna structure 102. The two short stub feedback lines (i.e., the first short stub feedback line 106A and the second short stub feedback line 106B) are used to tune the impedance of the antenna structure 102 by changing the size of the antenna structure 102, and create a bandpass filter. Therefore, the microstrip antenna 100 includes antenna (particularly C-band antenna) properties and bandpass filter properties by virtue of the antenna structure 102 and the feedback structure. These two short stub feedback lines can also be referred to as quasi-stub feedback lines. Figure 5A The figures describe in detail the passband characteristics of the two short-stub feedback lines (ie, the first short-stub feedback line 106A and the second short-stub feedback line 106B).

[0039] According to an embodiment, each of the two short stub feedback lines terminates close to the feed point 108 of the antenna structure 102. The two short stub feedback lines (i.e., the first short stub feedback line 106A and the second short stub feedback line 106B) terminate close to the feed point 108 of the antenna structure 102 to create a quasi-transmission line between the antenna structure 102 and the two short stub feedback lines. In addition, this feature enables the microstrip antenna 100 to have a more compact design.

[0040] According to an embodiment, each of the two short stub feedback lines extends along the edge of the compact area. The two short stub feedback lines (i.e., the first short stub feedback line 106A and the second short stub feedback line 106B) are placed along the edge of the compact area on the substrate 104, and enable the antenna structure 102 and the feedback structure to be manufactured on a single printed circuit board (PCB) without requiring a larger space.

[0041] According to an embodiment, the compact area is substantially rectangular or square, and the height and width are each in the range of 15 mm to 20 mm. In some implementations, the compact area is substantially rectangular or square, and the height and width are each 15 mm, 16 mm, 17 mm, 18 mm, 19 mm or even 16 mm, 17 mm, 18 mm, 19 mm or 20 mm. In the present embodiment, the width and height of the compact area of ​​the substrate 104 of the microstrip antenna 100 are 17 mm×17 mm, respectively. It should be understood by those of ordinary skill in the art that the shape of the compact area can be polygonal or circular without limiting the scope of the present disclosure, as long as the compact area is compact.

[0042] According to an embodiment, the antenna structure 102 includes a monopole antenna. According to the present application, the antenna structure 102 can be used as a monopole antenna. In the present embodiment, the antenna structure 102 is used as a monopole antenna. Therefore, the microstrip antenna 100 includes a monopole antenna (by using the antenna structure 102) and a bandpass filter (by using two short feedback lines, i.e., a first short feedback line 106A and a second short feedback line 106B).

[0043] According to an embodiment, the antenna structure 102 includes a dipole antenna. The antenna structure 102 can function as a dipole antenna if desired.

[0044] According to an embodiment, the operating frequency range is about 3.3 GHz to about 5.0 GHz. The microstrip antenna 100 is designed to operate in the C-band (i.e., 3.3 GHz to 5 GHz) for automotive applications, for example. However, it should be understood by those skilled in the art that using similar techniques and structures disclosed in the present disclosure, the microstrip antenna 100 can be designed to operate in the intermediate frequency for fifth generation (5G) mobile communications, such as 3.3 GHz to 4.2 GHz, 3.3 GHz to 3.8 GHz, 4.4 GHz to 5 GHz, etc.

[0045] Thus, the microstrip antenna 100 includes a monopole antenna (by using the antenna structure 102) and a bandpass filter (by using two short stub feedback lines, namely the first short stub feedback line 106A and the second short stub feedback line 106B). The microstrip antenna 100 integrates the bandpass filter into the antenna structure 102. By using the bandpass filter as part of the antenna structure 102, it is possible to create a fairly compact design. Compared with the traditional distributed filter, the bandpass filter has the advantages of a distributed filter while having a relatively small size. In this way, the microstrip antenna 100 has significantly low losses and a compact design. In addition, compared with the traditional lumped SMD filter, the microstrip antenna 100 significantly reduces the effects of SMD component aging and improves reliability. In addition, the microstrip antenna 100 does not require additional space on the main printed circuit board (PCB) and has no negative impact on the antenna efficiency compared with the traditional lumped SMD filter. Therefore, due to the integrated bandpass filter, the microstrip antenna 100 provides high efficiency, low loss and compact size, suitable for use in ultra-wideband wireless networks. The microstrip antenna 100 is also used in an automotive antenna system (AAS) in the C-band (ie, 3.3 GHz to 5 GHz) frequency.

[0046] Figure 2 is a graphical representation showing the bandpass characteristics of a microstrip antenna according to an embodiment of the present disclosure. Figure 2 Combination Figure 1 The components in the reference Figure 2 , a graphical representation 200 is shown, which shows, for example, a microstrip antenna 100 ( Figure 1 ) of a microstrip antenna. The graphical representation 200 includes an X-axis 202A representing frequency in GHz and a Y-axis 202B representing a reflection parameter (S(1,1)) in decibels (dB).

[0047] In the graphical representation 200, a first line 204 represents the passband characteristic of the microstrip antenna 100. The passband characteristic of the microstrip antenna 100 (represented by the first line 204) includes a passband in the frequency range of 3.3 GHz to 5 GHz. In the graphical representation 200, a first vertical line 206A represents the lower cutoff frequency (i.e., 3.3 GHz) of the passband of the microstrip antenna 100. A second vertical line 206B represents the upper cutoff frequency (i.e., 5 GHz) of the passband of the microstrip antenna 100. Therefore, frequencies in the passband (i.e., 3.3 GHz to 5 GHz) pass through the microstrip antenna 100, and the remaining frequencies are blocked.

[0048] Figures 3A to 3B The transition from band-stop to band-pass in the Smith chart of the microstrip antenna according to an embodiment of the present disclosure is shown. Figures 3A to 3B Combination Figure 1 The components in the reference Figure 3A , a graphical representation 300A is shown showing the band-rejection characteristics of a conventional microstrip antenna in a Smith chart. Figure 3B , a graphical representation 300B is shown, which shows a Smith chart showing, for example, a microstrip antenna 100 ( Figure 1 ) is a microstrip antenna with a bandpass characteristic. Usually, the Smith chart is a circular chart used to analyze the impedance of the antenna.

[0049] In graphical representation 300A, circular graph 302 represents the band rejection characteristics of a conventional microstrip antenna in the Smith chart. In the conventional microstrip antenna, the feedback stub (or λ / 4 line) is used as a narrowband band rejection filter (or notch filter). In graphical representation 300B, circular graph 304 represents the band rejection characteristics of the microstrip antenna 100 ( Figure 1 ). The feedback stub (i.e., λ / 4 line) of the conventional microstrip antenna is converted from a narrowband rejection filter to a bandpass filter of the microstrip antenna 100 through impedance tuning. The impedance of the microstrip antenna 100 is tuned by changing the antenna size using two stub feedback lines (i.e., the first stub feedback line 106A and the second stub feedback line 106B). Therefore, the microstrip antenna 100 realizes the characteristics of a bandpass filter on the conventional microstrip antenna. Figures 4A to 4B Figures 1 and 2 describe in detail the amplitude-frequency conversion from a band-stop to a band-pass filter.

[0050] Figures 4A to 4B The conversion of the amplitude-frequency of the microstrip antenna from band-stop to band-pass according to an embodiment of the present disclosure is shown. Figures 4A to 4B Combination Figure 1 , 3A and 3B. Figure 4A , a graphical representation 400A is shown, which illustrates the band-rejection characteristics of a conventional microstrip antenna. Figure 4B, shows a graphical representation 400B showing, for example, a microstrip antenna 100 ( Figure 1 )'s bandpass characteristics of a microstrip antenna.

[0051] The graphical representation 400A includes an X-axis 402A representing frequency and a Y-axis 402B representing a reflection parameter (S11). In the graphical representation 400A, a first line 404 represents a band-stop characteristic of a conventional microstrip antenna. In a conventional microstrip antenna, a feedback stub acts as a narrowband band-stop filter.

[0052] The graphical representation 400B includes an X-axis 406A representing frequency and a Y-axis 406B representing a reflection parameter (S11). In the graphical representation 400B, a first line 408 represents the bandpass characteristic of the microstrip antenna 100. The feedback stub of a conventional microstrip antenna is converted from a narrowband rejection filter to a bandpass filter of the microstrip antenna 100 by impedance matching.

[0053] Figure 5A is a graphical representation showing the frequency response of a feedback stub of a microstrip antenna according to an embodiment of the present disclosure. Figure 5A Combination Figure 1 and 2 The components in the reference Figure 5A , shows a graphical representation 500A showing, for example, a microstrip antenna 100 ( Figure 1 ) of the microstrip antenna. The graphical representation 500A includes an X-axis 502A representing frequency and a Y-axis 502B representing a reflection parameter (S11). The feedback stubs correspond to the first stub feedback line 106A and the second stub feedback line 106B of the microstrip antenna 100.

[0054] In graphical representation 500A, first line 504 represents the frequency response of first stub feedback line 106A of microstrip antenna 100. First stub feedback line 106A functions as filter 1 of microstrip antenna 100. Second line 506 represents the frequency response of second stub feedback line 106B of microstrip antenna 100. Second stub feedback line 106B functions as filter 2 of microstrip antenna 100. Third line 508 represents the frequency response of antenna structure 102 of microstrip antenna 100. Antenna structure 102 functions as a monopole antenna. First line 504, second line 506, and third line 508, when combined together, collectively represent the bandpass characteristics of microstrip antenna 100, Figure 5B Figures 2 and 3 describe the bandpass characteristics in detail.

[0055] Figure 5B is a graphical representation showing the bandpass characteristics of a microstrip antenna according to an embodiment of the present disclosure. Figure 5B Combination Figure 1 , 2 and 5A are described. Figure 5B , a graphical representation 500B is shown, which shows the bandpass characteristics when the frequency responses of the feedback stubs (i.e., the first stub feedback line 106A and the second stub feedback line 106B) of the microstrip antenna 100 and the monopole antenna (i.e., the antenna structure 102) are combined. The graphical representation 500B includes an X-axis 510A representing frequency and a Y-axis 510B representing a reflection parameter (S11).

[0056] In the graphical representation 500B, the first line 512 represents the bandpass characteristic of the microstrip antenna 100. The bandpass characteristic of the microstrip antenna 100 (represented by the first line 512) is obtained by combining the frequency responses of the two short stub feedback lines (i.e., the first short stub feedback line 106A and the second short stub feedback line 106B) of the microstrip antenna 100 and the monopole antenna (i.e., the antenna structure 102), the frequency responses of which are respectively Figure 5A The first line 504, the second line 506 and the third line 508 are represented in FIG.

[0057] The microstrip antenna 100 is specially designed for C-band frequency, has a passband from 3.3 GHz to 5 GHz, and any frequency below 3.3 GHz and above 5 GHz is blocked. The microstrip antenna is used in automotive applications such as automotive antenna systems (AAS). However, using similar techniques and structures disclosed in the present disclosure, the microstrip antenna 100 can be designed to operate in different frequency bands, such as a lower frequency band for mobile communications (i.e., 618 MHz to 960 MHz), a mid-frequency band for mobile communications (i.e., 1.42 GHz to 2.2 GHz), a higher frequency band for mobile communications (i.e., 2.30 GHz to 2.69 GHz), a lower frequency band for wifi communications (i.e., 2.40 GHz to 2.49 GHz), a higher frequency band for wifi communications (i.e., 5.15 GHz to 5.87 GHz), a lower frequency band for Bluetooth low energy communications (i.e., 2.40 GHz to 2.48 GHz), different frequency bands for global navigation satellite systems, CAR2X (i.e., 5.85 GHz to 5.92 GHz), and the like.

[0058] Without departing from the scope of the present disclosure as defined by the appended claims, the embodiments of the present disclosure described above may be modified. Expressions such as "including", "combined with", "having", "is / are" and the like used to describe and claim the present disclosure are intended to be interpreted in a non-exclusive manner, that is, items, components or elements that are not explicitly described are allowed to exist. References to the singular should also be interpreted as involving the plural. The word "exemplary" used herein means "as an example, instance or illustration". Any embodiment described as "exemplary" is not necessarily interpreted as being more preferred or more advantageous than other embodiments, and / or excluding the combination of features of other embodiments. The word "optionally" used herein means "provided in some embodiments and not provided in other embodiments". It should be understood that certain features of the present disclosure described in the context of a separate embodiment for the sake of clarity may also be provided in a single embodiment by combination. Conversely, the various features of the present disclosure described in the context of a single embodiment for the sake of clarity may also be provided individually or by any suitable combination or as any other described embodiment of the present disclosure.

Claims

1. A microstrip antenna (100) for operating within an operating frequency range, characterized in that: include: An antenna structure (102) printed in a compact area on a substrate (104); a feedback structure printed within the compact area on the substrate (104), wherein the feedback structure is configured to function as an impedance matched bandpass filter having a passband defining the operating frequency range; The feedback structure comprises two stub feedback lines (106A, 106B) arranged on either side of a feed point (108) of the antenna structure (102), wherein the stub feedback lines are configured as a bandpass filter; Each of the two stub feedback lines (106A, 106B) terminates proximate to the feed point (108) of the antenna structure (102); Each of the two stub feedback lines (106A, 106B) extends along an edge of the compact area.

2. The antenna according to claim 1, characterized in that The compact area is rectangular, with a height and a width each ranging from 15 mm to 20 mm.

3. The antenna according to claim 1 or 2, characterized in that: The antenna structure (102) comprises a monopole antenna.

4. The antenna according to claim 1 or 2, characterized in that: The antenna structure (102) comprises a dipole antenna.

5. The antenna according to claim 1 or 2, characterized in that: The operating frequency range is 3.3 GHz to 5.0 GHz.

6. The antenna according to claim 1 or 2, characterized in that: The two stub feedback lines (106A, 106B) are used to tune the impedance of the antenna structure (102) by changing the size of the antenna structure (102) and create a bandpass filter; The first stub feedback line (106A) of the two stub feedback lines (106A, 106B) is used as a first band-pass filter, and the second stub feedback line (106B) of the two stub feedback lines (106A, 106B) is used as a second band-pass filter.

7. The antenna according to claim 1 or 2, characterized in that: Each of the two stub feedback lines (106A, 106B) terminates proximate to the feed point (108) of the antenna structure (102) to create a quasi-transmission line between the feed point (108) of the antenna structure (102) and the two stub feedback lines (106A, 106B).

8. The antenna according to claim 1 or 2, characterized in that: The feedback structure is integrated in the antenna structure (102).

9. The antenna according to claim 6, characterized in that: The first stub feedback line (106A) has a first line (504), and the first line (504) is a frequency response generated by the first stub feedback line (106A) in a first frequency region of an operating frequency range through impedance matching. The second stub feedback line (106B) has a second line (506), the second line (506) is a frequency response generated by the second stub feedback line (106B) in a second frequency region of the operating frequency range through impedance matching, and the antenna structure (102) has a third line (508), the third line (508) is a frequency response generated by the antenna structure (102) in a third frequency region of the operating frequency range; The first frequency region and the second frequency region are adjacent to the third frequency region at an upper side and a lower side of the third frequency region, respectively.

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