COMMUNICATION DEVICE INCLUDES RETROREFLECTION STRUCTURE - Patent application

Abstract

To suppress a surface wave in a communication device (100) for a wireless communication system (500).SOLUTION: A communication device (100) includes a dielectric layer (106) extending along a plane (P) between a chassis (102) and a glass layer (104), an antenna element (108) configured to radiate radio waves (120), and a retroreflective structure (110) extending into the dielectric layer (106) and disposed adjacent to the antenna element (108), and the retroreflective structure (110) is configured to reflect the radio waves (120) at an angle non-parallel to the plane (P). Thus, the retroreflective structure (110) prevents parasitic channeling of antenna energy into surface waves in and behind the glass layer (104) and directs the radiation in a desired direction, thereby improving the radiation pattern and antenna gain.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a communication device that includes a retroreflective structure for reflecting radio waves radiated by an antenna element of the communication device. [Background technology]

[0002] Recently, smartphones have played an important role in our daily activities, not only for communication but also for media applications. Media applications may involve, for example, processing, storing, or transmitting audio or video content. Smartphones should be compact and provide a robust feel, while remaining affordable. One popular design includes an entire display covered with glass and framed by a sturdy metal alloy frame. Other components, such as a camera, battery, and integrated circuits, are located under the glass. Furthermore, smartphones for transmitting media content require high data rates. Frequencies above 20 GHz, which correspond to wavelengths in the millimeter-wave range, may be utilized. Implementing antennas under smartphone glass is cumbersome and can result in disturbances to the radiation pattern and reduced antenna gain, especially at higher frequencies. Summary of the Invention

[0003] It is an object of embodiments of the present invention to provide a solution that alleviates or overcomes the drawbacks and problems of conventional solutions.

[0004] The above and further objects are solved by the elements of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

[0005] According to a first aspect of the present invention, the above and other objects are achieved by a communication device for a wireless communication system, the communication device comprising: A chassis, A glass layer; a dielectric layer extending along a surface between the chassis and the glass layer; an antenna element configured to radiate radio waves; and a retroreflective structure extending within the dielectric layer and positioned adjacent to the antenna element, the retroreflective structure configured to reflect radio waves at angles non-parallel to the surface.

[0006] Retroreflective structures can be configured to have an angle of reflection that is the same as the angle of incidence, and may further be referred to as reflective metasurfaces, extraordinary reflective metasurfaces, or beam-shaping metasurfaces.

[0007] The location of the retroreflective structure adjacent to the antenna element is understood herein to mean that the interaction between the retroreflective structure and the antenna element is referred to as the near field and occurs before the radio waves form a wavefront. The distance between the retroreflective structure and the antenna element may be, for example, less than half the wavelength of the radio waves.

[0008] The dielectric layer here can be understood as various components disposed between the chassis and the glass layer of the communication device. The above components of the dielectric layer vary for different locations of the antenna element within the communication device. In embodiments, the antenna element may be disposed on the back surface of the communication device. Non-limiting examples of the dielectric layer may include air-filled gaps between adjacent components, foam or plastic structures used as spacers, the dielectric substrate of a printed circuit board, etc. In embodiments, the antenna element may be disposed as an edge of the communication device. Non-limiting examples of the dielectric layer may include insert molding, plastic parts, foam or plastic structures, and the dielectric substrate of a printed circuit board. In further embodiments, the antenna element may be disposed on the display surface of the communication device. Non-limiting examples of the dielectric layer may include display structures including polarizing films, adhesive films, organic light-emitting diode (OLED) substrates, and liquid crystal (LC) films.

[0009] An advantage of the communications device according to the first aspect is that it prevents parasitic channeling of antenna energy into surface waves in and behind the glass layer, and instead directs the radiation in a desired direction, thereby improving the radiation pattern and gain of the antenna element in the communications device.

[0010] In an implementation of the communication device according to the first aspect, the retroreflective structure has a non-uniform impedance along its extension within the dielectric layer.

[0011] The advantage of this implementation is that it allows for a small area retroreflective structure (e.g., smaller than half a wavelength) while preventing parasitic channeling of antenna energy into surface waves, thereby improving the radiation pattern.

[0012] In an implementation of the communication device according to the first aspect, the retroreflective structure is conductively or capacitively coupled to the antenna element.

[0013] The advantage of this implementation is that the structure is strongly excited by the near field of the antenna elements and therefore effectively reflects radiation in the desired direction.

[0014] In an implementation of the communication device according to the first aspect, the first end of the retroreflective structure is conductively or capacitively coupled to the antenna element.

[0015] An advantage of this implementation is that the parasitic channel between the retroreflecting structure and the antenna ground plane is eliminated. Because the retroreflecting structure is coupled to the antenna element, it does not allow excitation of its guided modes. Guided modes are parasitic to the antenna, and non-radiated electromagnetic (EM) energy guided along the dielectric layer reduces radiated EM energy. Thus, the disclosed implementation eliminates waves propagating along the ground plane inside the dielectric layer, further improving antenna efficiency.

[0016] In an implementation of the communications device according to the first aspect, the retroreflective structure is positioned within a range r from the antenna element that is less than half the wavelength of the radio wave.

[0017] An advantage of this implementation is that the footprint of the retroreflective structure is minimized and does not impair the performance of other device components placed under the glass.

[0018] In an implementation of the communication device according to the first aspect, the antenna element is arranged perpendicular or parallel to the plane of the dielectric layer.

[0019] An advantage of this implementation is that the retroreflecting structure can function with antennas of different configurations: for example, an antenna aperture generally parallel to the plane of the dielectric layer provides broadside beamforming radiation, and an antenna aperture generally perpendicular to the plane of the dielectric layer provides endfire beamforming radiation.

[0020] In an implementation of the communication device according to the first aspect, the retroreflective structure has an extension into the dielectric layer that is less than half the wavelength of the radio wave.

[0021] The advantage of this implementation is that it is a compact structure and does not impair the performance of other devices placed below the glass layer.

[0022] In an implementation of the communication device according to the first aspect, the retroreflective structure is a conductive film.

[0023] The advantage of this implementation is that it is easy to fabricate as a patterned metal layer.

[0024] In an implementation of the communication device according to the first aspect, the conductive film includes a solid conductive film.

[0025] The advantage of this implementation is that the manufacturing of solid conductive films allows for cost-effective designs.

[0026] In an implementation of the communication device according to the first aspect, the conductive film includes capacitive and inductive elements that form capacitive and inductive patterns.

[0027] The advantage of this implementation is that it allows for the surface impedance required for the operation of the retroreflective structure. This implementation allows for design integration of antenna beamforming. The conductive film can be configured to reflect radio waves at angles non-parallel to the surface.

[0028] In an implementation of the communication device according to the first aspect, the size of each capacitive element and each inductive element is smaller than 1 / 4 of the wavelength of the radio wave.

[0029] The advantage of this implementation is that the retroreflector acts as a non-uniform impedance boundary, which is required to operate as a retroreflector, allowing for a non-resonant frequency response, whereby radio waves are reflected in the desired direction in space for each frequency of multi-band antenna operation, without reflection back to the radiating source.

[0030] In an implementation of the communication device according to the first aspect, the capacitive and inductive patterns are non-repeating patterns.

[0031] The advantage of this implementation is that instead of a conventional periodic stop band structure that only prohibits the propagation of surface waves, the retroreflective structure can reflect the waves in a desired direction, and in this implementation, near-field conversion of surface waves into radiated waves is performed in a short section, e.g., less than half a wavelength.

[0032] In an implementation of the communication device according to the first aspect, the capacitive and inductive patterns form a grid pattern.

[0033] The advantage of this implementation is that it allows for the repetition of several sets of capacitive and inductive elements as a supercell in a longer structure, further improving performance.

[0034] In an implementation of the communication device according to the first aspect, the radio waves are transverse magnetic polarized radio waves.

[0035] An advantage of this implementation is that it works for antennas that radiate transverse magnetically polarized radio waves, which have the strongest coupling with parasitic surface waves along the device cover, and therefore converting transverse magnetically polarized radio waves into radiated waves allows for dual-polarized beamforming of the antenna.

[0036] According to a second aspect of the present invention, the above and other objects are achieved in a method for fabricating a communication device for a wireless communication system, the method comprising: obtaining a chassis and a glass layer; obtaining a dielectric layer extending in a plane and including a retroreflective structure extending therein, the retroreflective structure being configured to reflect radio waves at angles non-parallel to the plane; disposing a dielectric layer between the chassis and the glass layer; positioning an antenna element adjacent to a retroreflective structure; conductively or capacitively coupling the antenna element to the retroreflecting structure.

[0037] The method according to the second aspect can be extended to an implementation form corresponding to an implementation form of the communication device according to the first aspect, and thus the implementation form of the method includes the features of the corresponding implementation form of the communication device.

[0038] The advantages of the method according to the second aspect are the same as those of the corresponding implementation of the communication device according to the first aspect.

[0039] Further applications and advantages of embodiments of the present invention will become apparent from the following detailed description. [Brief explanation of the drawings]

[0040] The accompanying drawings are intended to clarify and explain different embodiments of the present invention.

[0041] [Figure 1] 1 illustrates a schematic diagram of a communication device according to an embodiment of the present invention; [Figure 2a] 2 illustrates a schematic representation of a retro-reflecting structure and antenna elements in a communication device according to an embodiment of the present invention; [Figure 2b] 2 illustrates a schematic representation of a retro-reflecting structure and antenna elements in a communication device according to an embodiment of the present invention; [Figure 3a] 2 illustrates a schematic representation of a retro-reflecting structure and antenna elements in a communication device according to an embodiment of the present invention; [Figure 3b] 2 illustrates a schematic representation of a retro-reflecting structure and antenna elements in a communication device according to an embodiment of the present invention; [Figure 4a] The retroreflection concept and the transverse magnetic mode vectors and their projections are shown. [Figure 4b] The retroreflection concept and the transverse magnetic mode vectors and their projections are shown. [Figure 5] 1 illustrates a retroreflective structure model according to an embodiment of the present invention. [Figure 6a] 1 illustrates impedance discretization according to an embodiment of the present invention. [Figure 6b] 1 illustrates impedance discretization according to an embodiment of the present invention. [Figure 7a] 1 illustrates a retroreflective structure configuration according to an embodiment of the present invention. [Figure 7b] 1 illustrates a retroreflective structure configuration according to an embodiment of the present invention. [Figure 7c] 1 illustrates a retroreflective structure configuration according to an embodiment of the present invention. [Figure 8] 3 shows the directionality for a conventional communication device and for a communication device according to the present invention. [Figure 9a] 1 illustrates directivity and gain improvements for a communication device of the present invention. [Figure 9b] 1 illustrates directivity and gain improvements for a communication device of the present invention. [Figure 10] 1 illustrates a method for a communication device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0042] The layer structure of conventional smartphones leads to surface waves excited by the internal antenna that traverse the screen glass and the dielectric layers located below the screen glass. These surface waves strongly distort the antenna's radiation pattern, reducing its gain and therefore should be avoided.

[0043] Conventional solutions to surface wave suppression can be grouped as volumetric and surface implementations. Volumetric solutions achieve wave suppression by changing the overall electrical properties of the layer material. Common volumetric approaches to wave suppression are based on electromagnetic bandgap structures (EBG), epsilon-negative materials (ENG), or muon-negative materials (MNG). Surface solutions are based on creating additional interfaces inside the dielectric layer. Such shape changes modify the dispersion properties of surface waves that can propagate within the dielectric layer.

[0044] A more realistic implementation can be obtained using a leaky wave antenna approach, where surface wave propagation is reduced by radiating some of the energy from the interface.

[0045] The above-mentioned solutions do not consider the antenna itself, but only the properties of the smartphone body as a combination of different layers. Better results can be achieved by modifying the antenna radiation pattern itself. Proposed solutions in this area include antenna devices fitted with multiple radiating conductors and dummy conductors in a multi-layered circuit board, and antenna devices fitted with a radiator surrounded by filter cells arranged on the board.

[0046] Previous solutions have shown promising results in terms of wave suppression or antenna radiation characteristic improvement under controlled conditions. Unfortunately, the assumptions selected for each solution are incompatible with the constraints imposed by the under-glass antennas of all-display smartphones. Smartphone design prioritizes the display over other device characteristics. Therefore, any structures located behind the glass should have little or no impact on display performance. This condition requires small antennas, which is not possible using previous solutions for surface wave suppression due to their large area requirements.

[0047] Additionally, some conventional solutions are implemented with volumetric structures that cannot be placed behind the glass without sacrificing antenna or display performance. In some implementations, the structure does not fit between the glass and the chassis, requiring changes to the smartphone dimensions without any guarantee of performance improvement. It should also be noted that the structure design should be compatible with actual manufacturing methods. However, manufacturing volumetric structures is difficult and expensive, and in practice, only thin, planar sheets of material are available.

[0048] In summary, conventional solutions for surface wave suppression promise good performance under ideal conditions, but compact implementation of these solutions is not possible, and therefore they are not suitable for antennas integrated into full-display smartphones.

[0049] The object of the present invention is to address the above-mentioned drawbacks and to provide a surface wave reflector designed to reflect electromagnetic waves that can excite surface waves. The present invention aims to improve the performance of an antenna located behind a glass layer in a communication device that utilizes a retroreflective structure. The retroreflective structure is positioned to prevent parasitic channeling of antenna energy into surface waves within and behind the glass layer, and directs radiation in a desired direction, thereby improving the radiation pattern and gain of the antenna in the communication device.

[0050] 1 schematically illustrates a communication device 100 for a wireless communication system according to an embodiment of the present invention. The communication device 100 includes a chassis 102, a glass layer 104, and a dielectric layer 106. Referring to FIG. 1, the dielectric layer 106 extends along a plane P between the chassis 102 and the glass layer 104. The dielectric layer 106 may also be referred to as a dielectric display or a dielectric spacer.

[0051] The communication device 100 further includes an antenna element 108 and a retro-reflective structure 110. The antenna element 108 is configured to radiate radio waves 120. In an embodiment, the radio waves 120 may be transverse magnetically polarized radio waves.

[0052] 1 , the retroreflective structure 110 extends within the dielectric layer 106 and is disposed adjacent to the antenna element 108. In an embodiment, the retroreflective structure 110 may be conductively or capacitively coupled to the antenna element 108. For example, a first end of the retroreflective structure 110 may be conductively or capacitively coupled to the antenna element 108.

[0053] The retroreflective structure 110 is configured to reflect the radio waves 120 emitted by the antenna elements 108 at angles non-parallel to the plane P. The angle of reflection of the retroreflective structure 110 is the same as or substantially the same as the angle of incidence. Thus, the angle non-parallel to the plane P at which the retroreflective structure 110 reflects the radio waves 120 is the same as the angle at which the radio waves 120 are incident on the retroreflective structure 110. Thus, the retroreflective structure 110 acts as an effective boundary for reflecting the radio waves 120 from the antenna elements 108 back to the antenna elements 108.

[0054] The reflection phase of the retroreflected wave can be manipulated by adjusting the topology of the retroreflecting structure 110. According to an embodiment of the present invention, the retroreflecting structure 110 has a non-uniform impedance along its extension within the dielectric layer 106. In this manner, a desired phase synchronization between the incident surface wave and the reflected radiation wave can be ensured. Further details regarding the topology of the retroreflecting structure 110 are described below with reference to Figures 4-7.

[0055] By utilizing the near-field region proximate to the antenna element 108, the retroreflective structure 110 may be utilized as a beamforming surface for the antenna element 108. The near-field region may be defined as up to half the wavelength of the radio wave. Thus, in embodiments, the retroreflective structure 110 may be positioned within a range r from the antenna element 108 that is less than half the wavelength of the radio wave 120. Furthermore, the retroreflective structure 110 may have an extension into the dielectric layer 106 that is less than half the wavelength of the radio wave 120.

[0056] According to an embodiment of the present invention, the retroreflective structure 110 is a conductive film 112. Thus, the retroreflective structure 110 may be a thin, flat structure extending within the dielectric layer 106, with a primary extension along the plane P. The conductive film 112 may include a solid conductive film, or the conductive film 112 may include capacitive and inductive elements that form capacitive and inductive patterns.

[0057] In embodiments in which the conductive film 112 includes capacitive and inductive elements, the size of each capacitive and inductive element may be less than one-quarter of the wavelength of the radio wave 120. Thus, the capacitive and inductive elements may form sub-wavelength-spaced capacitive and inductive patterns. The capacitive and inductive patterns may also be non-repeating, e.g., non-periodic. In this manner, resonance due to periodicity may be prevented. Furthermore, the capacitive and inductive patterns may form a grid pattern. The capacitive and inductive patterns may be designed as a group of grid impedance strips, e.g., using discrete values ​​of a reflector grid impedance function, as described further below.

[0058] The antenna element 108 can be arranged perpendicular or parallel to the plane P of the dielectric layer 106, or in any other suitable orientation. FIGS. 2a-2b schematically illustrate an embodiment in which the antenna element 108 is arranged perpendicular to the plane P of the dielectric layer 106. In the embodiment illustrated in FIGS. 2a-2b, the antenna element 108 is a monopole, and the retroreflective structure 110 is a conductive film 112 including capacitive elements 114a, 114b, ..., 114n and inductive elements 116a, 116b, ..., 116n, forming capacitive and inductive patterns. Metal elements of the antenna structure partition the volume between the conductive film 112 and the chassis / ground plane 102, preventing the excitation of guided waves between the conductive film 112 and the chassis / ground plane 102. For example, this can be ensured by conductively coupling the antenna element 108 to a first end 110a of the retroreflective structure 110, as shown in FIG. 2b.

[0059] 3a-3b schematically illustrate an embodiment in which the antenna element 108 is disposed parallel to the plane P of the dielectric layer 106. In the embodiment illustrated in FIGS. 3a-3b, the antenna element 108 is a monopole, and the retroreflective structure 110 is a solid conductive film 112. The retroreflective structure 110 is further conductively coupled to the antenna element 108. A metal element of the antenna structure partitions the volume between the conductive film 112 and the chassis / ground plane 102, preventing the excitation of guided waves between the conductive film 112 and the chassis / ground plane 102. By way of example, this can be ensured by conductively coupling the antenna element 108 to a first end 110a of the retroreflective structure 110, as shown in FIG. 3b.

[0060] The above-described embodiments are just two examples of possible combinations of antenna element placement and types of retroreflective structure 110. However, other combinations are possible without departing from the scope of the present invention. For example, the antenna elements 108 may be placed perpendicular to the plane P of the dielectric layer 106 and the retroreflective structure 110 may be a solid conductive film, or the antenna elements 108 may be placed parallel to the plane P of the dielectric layer 106 and the retroreflective structure 110 may be a conductive film 112 that forms capacitive and inductive patterns.

[0061] The retroreflective structure 110 allows waves incident from space to be redirected back towards the source of the incident waves, as shown in Figure 4a.

[0062] According to embodiments of the present invention, the retroreflective structure 110 can be implemented as a metasurface that can tune the surface impedance to tune the desired phase locking between the incident and reflected waves, defined via the following boundary conditions:

[0063]

number

[0064] where E t and H tare the total, i.e., incident plus reflected, tangential components of the electric and magnetic fields,

[0065]

number

[0066] is a unit vector normal to the surface. Therefore, it is important to define the tangential components of both the electric and magnetic fields to provide the desired retroreflective effect.

[0067] Due to the desired polarization of the field, the retroreflecting structure 110 can be designed for transverse magnetic (TM) polarization with no perpendicular component of the magnetic field. Based on the coordinate definitions shown in Figure 4b, the tangential components of the incident and reflected magnetic fields can be written as follows:

[0068]

number

[0069] where:

[0070]

number

[0071] is the reflection coefficient (

[0072]

number

[0073] is the phase of the reflection coefficient), and θ i is the angle of incidence. To find the electric field components of the TM wave,

[0074]

number

[0075] Ampere's law with time-harmonic dependence of

[0076]

number

[0077] is used, and ε is the permittivity of the background medium, which is assumed to be a vacuum. The tangential electric field is therefore:

[0078]

number

[0079] Using equation (1), the tangential components of the total magnetic and electric fields are the reflected and incident fields (respectively,

[0080]

number

[0081] and

[0082]

number

[0083] ), the surface impedance that models the retroreflective structure 110 is

[0084]

number

[0085] where,

[0086]

number

[0087] is the phase gradient introduced by the metasurface. The required phase gradient for the retroreflective structure 110 results in a frequency-dependent surface impedance. From the definition of the phase gradient, the period of the retroreflective structure 110 is calculated as follows:

[0088]

number

[0089] As the angle of incidence decreases, the period increases, and in the limit of zero angle, i.e., normal incidence, the retroreflective structure 110 degenerates into a regular uniform mirror. In either case, the compact retroreflective structure 110 will respond to fields near the antenna, and therefore only one period of the surface impedance is required.

[0090] In communication device 100, it is more convenient to use the glass surface as a reference to create the impedance of retroreflective structure 110, as shown in Figures 5a-5c. Retroreflective structure 110 located inside dielectric layer 106 will introduce discontinuities in the tangential magnetic field on both sides of it, resulting in a grid impedance Z g It can be modeled as:

[0091] The electromagnetic field is oriented at an angle θ with respect to the surface of the retroreflective structure 110. i The vertical component

[0092]

number

[0093] and the tangential component

[0094]

number

[0095] Incident electromagnetic field coefficients with

[0096]

number

[0097] is a glass cover layer having a thickness d3, a dielectric layer between the glass cover layer and the conductive pattern 112 layer d2, and a grid impedance Z of the conductive pattern 112. g , and is reflected by the surface of the multilayer retroreflective structure 110, which has a dielectric layer between the conductive pattern 112 and the ground plane d1. The impedances of the dielectric layers Z1, Z2, and Z3, and the grid impedance Z g (FIG. 5b) shows the surface impedance Z s can be converted to

[0098] To ensure that the multilayer structure behaves as a retroreflector on a glass surface, it is necessary to mimic the behavior of the surface impedance defined in equation (6). Using a transmission line approach, the input impedance of the multilayer system can be calculated and equalized to the desired value, as shown in Figure 5b. The resulting expression for the required grid impedance, as a function of the surface impedance and other parameters of the multilayer system, can be written as follows:

[0099]

number

[0100] where:

[0101]

number

[0102] and

[0103]

number

[0104] where n∈[1,2,3] numbers the dielectric layers.

[0105] FIG. 6a shows the discretization of the grid and surface impedance shapes. It is important to note that both the grid and surface impedance are continuous functions along the surface in the x-direction. This problem can be tricky for surface mounting because the retroreflective structure 110 is realized as a set of finite-sized elements. Therefore, the retroreflective structure 110 is discretized into strips with constant grid impedance values, as schematically represented in FIG. 6b, replacing the continuous functions with a stepped constant approximation. A good tradeoff between performance and complexity can be achieved by selecting an appropriate number of discrete values.

[0106] 7a-7c show an embodiment in which the retroreflective structure 110 is discretized into six elements. The elements can be fabricated, for example, based on a serpentine slot topology. FIG. 7a shows one element of the serpentine slot-based retroreflective structure 110. Each element includes two metal patches 116a, 116b separated by a gap or slot 114a between them. The grid impedance Zg can be adjusted by varying the length A and width w of the slot gap. FIG. 7b shows the shape of the retroreflective structure 110 along the y-axis, which is designed to achieve the desired retroreflective function.

[0107] 7c shows the location of the retroreflective structure 110 within the dielectric layer 106. The retroreflective structure 110 is located in the center of the dielectric layer 106 below the glass layer 104 in this application.

[0108] Table 1 considers glass with a thickness of 0.5 mm and a relative dielectric constant of 5.5, and the incident angle θ i = 85°, and the dielectric layer 106 was characterized as a 1.0 mm slab with a relative dielectric constant of 2.7.

[0109] [Table 1]

[0110] In the embodiment shown in Figure 7c, the required optimum impedance values ​​given in Table 1 reveal that none of the discretized strips require operation near resonance, and furthermore, retroreflective structure 110 utilizes only capacitive grid elements, thereby allowing retroreflective structure 110 to operate over a wider frequency range than other conventional structures that can only operate in a resonant region within a narrow frequency band.

[0111] In terms of size, the proposed retroreflective structure 110 is a suitable compact solution since its length is reduced to one phase period of Equation 6. In the scenario discussed above, the length of the retroreflective structure 110 is approximately 5.2 mm, less than half a wavelength at a reference frequency of 29 GHz, while each element occupies 1 / 6 of the total length. The element length can be further reduced using appropriate manufacturing methods if more discretization points are utilized.

[0112] The retroreflective structure 110 of the present invention not only blocks the propagation of surface waves within the dielectric layer 106, but also redirects this energy in a desired direction, as shown in Figure 8. Figure 8 shows the directivity at 29 GHz for two scenarios: the first scenario 802 shows the directivity for a communication device without a structure for surface wave suppression, and the second scenario 804 shows the directivity for the same communication device with an additional retroreflective structure 110 of the present invention in the center of the dielectric layer 106. Note that surface waves propagating below the glass in a 90° direction are suppressed by the retroreflective structure 110 and redirected to the region of interest on the top surface of the glass, i.e., in a 0° direction.

[0113] For different frequencies, the retroreflective structure 110 shows consistent improvements, as can be seen from Figures 9a-9b. Figure 9a shows the directivity improvement of the retroreflective structure 110, and Figure 9b shows the gain improvement of the retroreflective structure 110. The retroreflective structure 110 may exhibit an average directivity improvement of about 3 dB and a gain improvement of about 5 dB.

[0114] The present invention further relates to a method for manufacturing a communication device 100 according to any of the described embodiments. Figure 10 shows a flowchart of method 200, which includes step 202 of obtaining a chassis 102 and a glass layer 104, and step 204 of further obtaining a dielectric layer 106 including a retroreflective structure 110 extending therein and extending in a plane P, the retroreflective structure 110 being configured to reflect radio waves 120 at angles non-parallel to the plane P. Method 200 further includes step 206 of disposing the dielectric layer 106 between the chassis 102 and the glass layer 104, and step 208 of disposing an antenna element 108 adjacent to the retroreflective structure 110. Method 200 further includes step 210 of conductively or capacitively coupling the antenna element 108 to the retroreflective structure 110.

[0115] The communication device 100 herein may be referred to as a user device, user equipment (UE), mobile station, Internet of Things (IoT) device, sensor device, wireless terminal, and / or mobile terminal, and may be capable of wireless communication in a wireless communication system, sometimes referred to as a cellular wireless system. A UE may also be referred to as a mobile phone, cellular telephone, computer tablet, or wirelessly enabled laptop. A UE in this context may be, for example, a portable, pocketable, handheld, computer-based, or vehicle-mounted mobile device capable of communicating voice and / or data with other entities, such as other receivers or servers, via a wireless access network. A UE may be a station (STA), which is any device that includes an IEEE 802.11-compliant medium access control (MAC) and physical layer (PHY) interface to the wireless medium (WM). A UE may also be configured for communication in fifth generation wireless technologies, such as 3GPP-related LTE and LTE-Advanced, WiMAX and its evolution, and new wireless.

[0116] Finally, it should be understood that the present invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

1. A communication device (100) for a wireless communication system (500), said communication device (100) comprising: a chassis (102); a glass layer (104); a dielectric layer (106) extending along a plane (P) between the chassis (102) and the glass layer (104); an antenna element (108) configured to radiate radio waves (120); a retroreflective structure (110) extending into the dielectric layer (106) and disposed adjacent to the antenna element (108), the retroreflective structure (110) configured to reflect the radio waves (120) at an angle non-parallel to the plane (P) and perform beamforming for the antenna element (108) via a near field generated by the antenna element (108) and the retroreflective structure (110), the retroreflective structure (110) having a non-uniform impedance along its extension within the dielectric layer (106). A communication device (100).

2. The retroreflective structure (110) is conductively or capacitively coupled to the antenna element (108). The communication device (100) of claim 1.

3. a first end of the retroreflective structure (110) conductively or capacitively coupled to the antenna element (108); The communication device (100) of claim 2.

4. the retroreflective structure (110) is positioned within a range (r) from the antenna element (108), the range (r) being less than half the wavelength of the radio wave (120); A communication device (100) according to any one of claims 1 to 3.

5. The antenna element (108) is arranged perpendicular or parallel to the plane (P) of the dielectric layer (106). A communication device (100) according to any one of claims 1 to 4.

6. the retroreflective structure (110) has an extension into the dielectric layer (106), the extension being less than half the wavelength of the radio wave (120); A communication device (100) according to any one of claims 1 to 5.

7. A communication device (100) for a wireless communication system (500), comprising: a chassis (102); a glass layer (104); a dielectric layer (106) extending along a plane (P) between the chassis (102) and the glass layer (104); an antenna element (108) configured to radiate radio waves (120); a retroreflective structure (110) extending into the dielectric layer (106) and disposed adjacent to the antenna element (108), the retroreflective structure (110) being configured to reflect the radio waves (120) at an angle non-parallel to the plane (P) and perform beamforming on the antenna element (108) via a near field generated by the antenna element (108) and the retroreflective structure (110), the retroreflective structure (110) being a conductive film (112). A communication device (100).

8. The conductive film (112) is a solid conductive film. The communication device (100) of claim 7.

9. The conductive film (112) includes capacitive elements (114a, 114b, ..., 114n) and inductive elements (116a, 116b, ..., 116n) that form capacitive and inductive patterns. The communication device (100) of claim 7.

10. The size of each capacitive element and each inductive element is less than 1 / 4 of the wavelength of the radio wave (120). The communication device (100) of claim 9.

11. the capacitive and inductive patterns are non-repeating patterns; A communication device (100) according to claim 9 or 10.

12. the capacitive and inductive patterns form a grid pattern; A communication device (100) according to any one of claims 9 to 11.

13. The radio wave (120) is a transverse magnetic polarized radio wave. A communication device (100) according to any one of claims 1 to 12.

14. A method (200) for fabricating a communication device (100) for a wireless communication system (500), said method (200) comprising: Obtaining (202) a chassis (102) and a glass layer (104); a step (204) of obtaining a dielectric layer (106) including a retroreflective structure (110) extending into the dielectric layer (106) and extending in a plane (P), the retroreflective structure (110) being configured to reflect radio waves (120) at angles non-parallel to the plane (P) for beamforming to the antenna element (108) via the antenna element (108) and a near field generated by the retroreflective structure (110), the retroreflective structure (110) having a non-uniform impedance along its extension within the dielectric layer (106); disposing (206) the dielectric layer (106) between the chassis (102) and the glass layer (104); positioning (208) the antenna element (108) adjacent to the retroreflective structure (110); conductively or capacitively coupling the antenna element (108) to the retro-reflective structure (110); A method (200) comprising:

15. A method (200) for fabricating a communication device (100) for a wireless communication system (500), the method (200) comprising: Obtaining (202) a chassis (102) and a glass layer (104); a step (204) of acquiring a dielectric layer (106) including a retroreflective structure (110) extending into the dielectric layer (106) and extending in a plane (P), the retroreflective structure (110) being configured to reflect radio waves (120) at an angle non-parallel to the plane (P) and to beamform to the antenna element (108) via the antenna element (108) and a near field generated by the retroreflective structure (110), the retroreflective structure (110) being a conductive film (112); disposing (206) the dielectric layer (106) between the chassis (102) and the glass layer (104); positioning (208) the antenna element (108) adjacent to the retroreflective structure (110); conductively or capacitively coupling the antenna element (108) to the retro-reflective structure (110); A method (200) comprising:

Images