Planar antenna and high frequency module equipped with same

Abstract

This planar antenna or this high-frequency module comprising the planar antenna has a structure that is easy to adjust for impedance matching over a broad bandwidth, and can be used in frequencies of a quasi-millimeter band or higher bands at low cost. The following is an explanation of an example of a planar antenna 1 in fig. 1.　Specifically, the planar antenna 1 has: a radiation element 21 formed on the obverse surface of a printed board 10 in which the reverse surface serves as a ground surface 11; an electricity supply line path 22; a first ground element 23 and a second ground element 24 that are each electrically connected to the ground surface 11, and that oppose each other with the electricity supply line path 22 interposed therebetween; a first passive element 25 that extends from the first ground element 23 so as to surround a portion of the radiation element 21; and a second passive element 26 that extends from the second ground element 24 in the opposite direction to the first passive element 25 so as to surround a portion of the radiation element 21. The first ground element 23 and the second ground element 24 operate as an impedance matching device for the electricity supply line path 22. The first passive element 25 and the second passive element 26 operate as an adjustment device of the signal phase of the radiation element 21.

Description

[Technical field]

[0001] The present invention relates to a planar antenna that can be used in a frequency band equal to or higher than the quasi-millimeter wave band, and a high-frequency module including the same. [Background technology]

[0002] Planar antennas used in microwave and higher frequency bands are significantly affected by the quality of matching with the feed line, the presence or absence of other high-frequency components placed near the antenna, etc. In addition, there is a demand for a wider usable frequency range for this type of planar antenna.

[0003] In this regard, the planar antenna disclosed in Patent Document 1 includes a central conductor and a ground conductor arranged on the same plane as the planar antenna. The central conductor is conductively connected to the planar antenna. The ground conductors are formed on both sides of the central conductor at a distance from the central conductor. A tapered region is formed in the ground conductor near the connection portion with the planar antenna, in which the distance between the edge of the ground conductor and the central conductor increases almost monotonically as the edge approaches the planar antenna. By forming the tapered region, matching between the planar antenna and the transmission line is achieved over a relatively wide frequency range, despite the planar type.

[0004] The planar antenna disclosed in Patent Document 2 does not adjust the shape of the ground conductor, which is a transmission line, as in Patent Document 1, but rather utilizes the effect of double resonance to achieve a broadband. That is, a loop conductor with a gap is placed on a dielectric substrate, and a straight conductor is placed inside the loop conductor. Then, the base end of the straight conductor and the loop conductor are fed with balanced power. This causes the loop conductor to function as a loop radiating element, and the straight conductor to function as a radiating element of a monopole antenna. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-121643 A [Patent Document 2] JP 2011-217204 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the planar antenna disclosed in Patent Document 1, when the central conductor and the ground conductor are configured with microstrips, the size of the substrate and each conductor becomes smaller as the operating frequency becomes higher. Therefore, the amount of change in the adjustable impedance becomes smaller. In addition, the adjustment of the tapered area is more complicated than the case of cutting out a rectangular area. Therefore, the adjustment work for matching takes time.

[0007] In the planar antenna configuration of Patent Document 2, the back surface of the dielectric substrate cannot be used as a ground plane, so a metal reflector must be placed parallel to the back surface of the dielectric substrate, at a distance of about 0.1 of the wavelength of the operating frequency.

[0008] In addition, for boards used in the 1 to 10 GHz band, FR (Flame Retardant)-4 grade printed circuit boards ("FR-4 boards") based on glass epoxy are generally used. The lower the dielectric constant ε of the insulator of a printed circuit board, the faster the signal transmission speed becomes, and the higher the frequency band used, the greater the transmission loss becomes. For this reason, in the past, for printed circuit boards used at frequencies above the quasi-millimeter wave band, high-frequency boards with low dielectric constant and low-loss fluororesin as an insulator have been used, rather than FR-4 boards with a high dielectric constant ε. However, high-frequency boards are several tens of times more expensive than FR-4 boards. Not only that, they are inferior to FR-4 boards in terms of mechanical properties (strength and durability) and processing. For this reason, it has been extremely difficult to mass-produce planar antennas that can be used at frequencies above the quasi-millimeter wave band.

[0009] Furthermore, making the board on which the radiating element is mounted thicker improves performance in terms of radiation efficiency and durability, but it also makes mismatching more likely to occur. For example, assume that the characteristic impedance of the feed line connected to the downstream electronic circuit is 50 Ω. In this case, the width of the feed line must be large to match the dielectric constant of the board, but as the feed line width increases, matching becomes more difficult. Furthermore, if mismatching occurs, the feed line itself will act as a radiating element, causing a decrease in radiation gain due to unwanted radiation and beam distortion due to the spread of electric field strength.

[0010] One example of an object of the present invention is to enable a planar antenna, or a high-frequency module including the same, to be used in the quasi-millimeter wave band while being low cost. [Means for solving the problem]

[0011] One aspect of the present invention is a planar antenna formed on the front surface of a substrate whose back surface is a ground plane, the planar antenna having a radiating element, a feed line connected to the radiating element, a first ground element and a second ground element each electrically conductive to the ground plane and laid in opposite directions across the feed line, a first parasitic element extending from the first ground element to surround at least a portion of the radiating element, and a second parasitic element extending from the second ground element in a direction opposite to the first parasitic element to surround at least a portion of the radiating element, the first ground element and the second ground element operating as an impedance matching device for the feed line and a reflector for the radiating element, and the first parasitic element and the second parasitic element operating as a signal phase adjuster and director of the radiating element.

[0012] Another aspect of the present invention is a high-frequency module including an antenna section present on the surface of a printed circuit board whose back surface is a ground conductor, the antenna section being a planar antenna of the above-described aspect, and characterized in that this planar antenna operates in a frequency band of 26 GHz or higher. Effect of the Invention

[0013] According to the above aspects, in a planar antenna or a high-frequency module including the same, it is possible to suppress the influence of the presence or absence of other high-frequency components arranged near the radiating element, etc. Also, it is possible to realize at low cost a structure that is easy to adjust for impedance matching over a wide band at frequencies of quasi-millimeter wave band or higher. [Brief description of the drawings]

[0014] [Figure 1] 1A to 1C are six-sided views showing a configuration example of a planar antenna according to a first embodiment. [Diagram 2] FIG. 2 is an explanatory diagram showing the size and other characteristics of the planar antenna according to the first embodiment. [Diagram 3] FIG. 4 is a frequency-VSWR characteristic diagram of the planar antenna of the first embodiment. [Figure 4] FIG. 2 is a diagram showing a radiation pattern of the planar antenna according to the first embodiment. [Diagram 5] FIG. 4 is a diagram showing a radiation pattern in a planar antenna of Comparative Example 1. [Figure 6] FIG. 11 is a diagram showing a radiation pattern in a planar antenna of Comparative Example 2. [Figure 7A] Radiation pattern when there are no high-frequency electronic components near the radiating element. [Figure 7B] FIG. 13 is a diagram showing a radiation pattern when a high-frequency electronic component is present near the radiating element. [Figure 8] FIG. 11 is a diagram showing a part of the configuration of a planar antenna according to a second embodiment. [Figure 9] FIG. 13 is a diagram showing a part of the configuration of a planar antenna according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [First embodiment] Below, we will explain an example embodiment in which the present invention is applied to a planar antenna that can be used in the 28 GHz band (26.5 GHz to 29.5 GHz), which is the high band of 5G (fifth generation mobile communication system), and has a tilt angle of approximately 15 degrees vertically upward from the ground surface. Fig. 1 is a six-sided view showing a configuration example of a planar antenna according to the first embodiment, Fig. 2 is a diagram showing the size and arrangement intervals of each component.

[0016] The planar antenna 1 shown in FIG. 1 has an antenna section 20 disposed on the surface of a printed circuit board 10 whose rear surface serves as a ground surface 11 . The printed circuit board 10 is a glass epoxy board, such as an FR-4 board (double-sided board), which is sufficient in terms of strength and durability at the technical level at the time of filing this application, but is considered unsuitable for use in the 5G frequency band due to large losses. In the first embodiment, in order to make the printed circuit board 10 as small as possible, the long side size W 10 18mm, short side size D 10 is 15mm, thickness T 10 The printed circuit board 10 used was a general-purpose printed circuit board with a thickness of 0.6 mm and a dielectric constant ε of 4.0. The ground surface 11 on the back side of the printed circuit board 10 was a copper foil surface with a thickness of 18 μm. The reason why the planar antenna 1 that can be used in the 28 GHz band, which is the high band of 5G, can be realized while using such a general-purpose and inexpensive FR-4 board as the printed circuit board 10 is due to the characteristic structure of the antenna unit 20 described below.

[0017] The antenna unit 20 has a radiating element 21, a feed line 22, a first ground element 23, a second ground element 24, a first parasitic element 25, and a second parasitic element 26, which are patterned with a conductive film having a thickness of 18 μm. The conductive film is, for example, any one of copper foil, silver foil, and gold foil, and constitutes a microstrip. The shapes and positions of these components 21 to 26 are symmetrical with respect to an extension line of the central axis of the feed line 22, as shown in FIG. 1 and FIG. 2. Because the thickness is extremely small, these components 21 to 26 are omitted from the left side, front, and rear of FIG. 1 and the front of FIG. 2. The antenna unit 20 also includes a sheet metal element 27 that is, for example, rectangular when unfolded and viewed from above, and substantially U-shaped (substantially J-shaped) when viewed from the side. The sheet metal element 27 may also be substantially L-shaped when viewed from the side. The shape and structure of the sheet metal element 27 will be described later.

[0018] The radiating element 21 may have any shape that operates as a resonant antenna. The radiating element 21 of the first embodiment has a substantially rectangular shape designed to have a size that resonates in the 28 GHz band. The size L of the short side of the radiating element 21 is 211 is approximately 3 / 8 of the wavelength of the center frequency (28.0 GHz) of the 28 GHz band (2.35 mm in this example), and the length of the long side L 212 is approximately half the wavelength (2.9 mm in this example).

[0019] NULL points occur in the radiating element 21. NULL points are regions where high-frequency currents are cancelled out due to the influence of reflected waves or interference waves during radiation. In antenna engineering, it is common to design the shape and size of the radiating element so as to minimize the occurrence of NULL points, and when their occurrence is unavoidable, to avoid them by taking measures such as providing a phase difference to the reflected waves. However, in the first embodiment, these NULL points are actively utilized.

[0020] That is, in the first embodiment, the portion where the null point occurs in the radiating element 21 is the feeding point 211, which is the connection portion with the feeding line 22. As a result, even if the width of the feeding line 22 increases due to the thickening of the printed circuit board 10, or the dielectric constant ε of the printed circuit board 10 varies, which makes it easier for mismatching to occur, the effect on the antenna characteristics (such as VSWR and directional characteristics) caused by this can be minimized. In addition, unnecessary radiation from the feeding line 22 caused by this can be prevented. This is one of the reasons why an inexpensive FR-4 board can be used even in high frequency bands above the quasi-millimeter wave band.

[0021] 1 and 2, the shape of the feed point 211 is shown as a rectangle that protrudes slightly toward the feed line 22 in order to eliminate unnecessary reflections between the radiating element 21 and the feed line 22 or to fine-tune impedance matching. However, the shape of the outer edge of the protruding part is not limited to the shape shown in the figures. For example, it may be an arc or trapezoid. Also, instead of a shape that protrudes toward the feed line 22, the feed point 211 may be a concave shape inside the radiating element 21, and the most recessed part may be used as the feed point 211.

[0022] The power supply line 22 has a line width W 221 (In this example, 1.1 mm) will gradually change to a line width of W 222 (In this example, 0.8 mm) and the smallest line width W 223 (In this example, it is molded to be 0.2 mm). The characteristic impedance of the feed line 22 is uniquely derived from a known formula for calculating the characteristic impedance of a microstrip line, which includes variables such as the line width W and the dielectric constant ε of the printed circuit board 10. In this example, the characteristic impedance is about 210 to 230 Ω (corrected to about 200 Ω by adjusting the outer edge shape of the protruding portion) at the feed point 211, and about 210 to 230 Ω (corrected to about 200 Ω by adjusting the outer edge shape of the protruding portion) at the line width W 221 The characteristic impedance and line width W 222 Approximately 50 Ω at the part, line width W 223 In other words, the feed line 22 in this example has a line width W 221 is the track width W 222 The first characteristic impedance change point where the line width W 222 is the track width W 223 However, the positions of the first characteristic impedance transition point and the second characteristic impedance transition point can be appropriately adjusted according to the distance between the first ground element 23 and the second ground element 24 required for matching.

[0023] Although the number of characteristic impedance change points is two in the first embodiment, it may be three or more. In this way, the power supply line 22 is shaped to form a plurality of characteristic impedance change points, so that impedance matching can be achieved over a wide frequency band.

[0024] Here, the line width W of the power supply line 22 221 The line width W 222 , the track width W 222 The line width W 223 The reason why the impedance is changed stepwise is mainly to facilitate fine adjustment for matching the characteristic impedance. That is, the work of accurately matching the cut amounts of both outer edges of the feed line 22 is much simpler than, for example, a tapered shape. 222 From track width W 223 The line width W 223 This is to eliminate unnecessary reflections with the line. Therefore, when unnecessary reflections do not occur, the line width W 222 From track width W 223 The angle of change to may be acute.

[0025] In the first embodiment, the first ground element 23 and the second ground element 24 have a substantially rectangular planar shape, and are each electrically connected to the ground surface 11 on the back surface of the printed circuit board 10 via a plurality of conductive through holes 111. Therefore, by providing a ground potential surface with a sufficiently large area for the antenna unit 20, it is possible to stabilize the operation. The length L of the long side of the first ground element 23 231 It is desirable to set the frequency to the higher side of the 28 GHz band. In this example, it is set to approximately one wavelength (5.0 mm in this example) of the frequency of 29.0 GHz. Also, the length of the short side L 232is set to approximately 1 / 2 wavelength or approximately 5 / 8 wavelength of the above frequency (3.5 mm in this example). However, the portion close to the second characteristic impedance change point of the feed line 22 and the portion close to the feed portion of the radiating element 21 are slightly larger in size than the other portions. These are measures to make the impedance matching wider bandwidth.

[0026] The radiating element 21, the feed line 22, and the first ground element 23 are impedance-matched by the reactance generated at the respective intervals. However, since the rear surface of the printed circuit board 10 is the ground surface 11, the radiating element 21 and the ground surface 11 are strongly coupled in the electric field. Therefore, in order to obtain a large reactance between the radiating element 21 and the first ground element 23, it is necessary to narrow the interval and achieve matching. However, since reactance changes are sensitive in the 28 GHz band, fine adjustment of the impedance becomes difficult. Therefore, in the first embodiment, a characteristic impedance change section is provided to facilitate fine adjustment of the reactance.

[0027] The main elements of the characteristic impedance changing section are the distance (the first gap resulting from this) between the radiating element 21 and the first ground element 23 (or the second ground element 24) and the distance (the second gap resulting from this) between the feed line 22 and the first ground element 23 (or the second ground element 24). The first gap ensures a required amount of reactance. Furthermore, the second gap changes in stages, thereby changing the characteristic impedance. The characteristic impedance changing section of the first embodiment has a line width W 222 The smallest gap D 223 (0.15mm), and the line width W 222 The largest gap D between the part facing the bulging part and the part facing the bulging part is 222 (0.5mm), and the line width W 222 The part facing the bulging part is the normal distance D 221 (0.3 mm). And within that interval, the line width W 223 and track width W 222 Change point, line width W 222 and track width W 221By adjusting the position of the change point, it is possible to further change the reactance, fine-tune the characteristic impedance, and achieve matching. This makes it possible to roughly achieve matching in the area close to the power feed point of the radiating element 21, and fine-tune the impedance matching at the characteristic impedance change point of the power feed line 22, making it possible to achieve impedance matching over a wide range.

[0028] The shape, size, and arrangement of the second ground element 24 are the same as those of the first ground element 23. The above description is about the distance between the first ground element 23 and the radiating element 21 and the feed line 22, but this description also applies to the distance between the second ground element 23 and the radiating element 21 and the feed line 22. Therefore, a description of the size, etc. is omitted in FIG.

[0029] In this way, the first ground element 23 and the second ground element 24 act as impedance matching elements (one of the impedance matching means) for the adjacent radiating element 21. As described above, the first ground element 23 and the second ground element 24 also act as a characteristic impedance changing section (another of the impedance matching means) that enables impedance matching over a wide band together with the feeder line 22 whose line width changes stepwise. Therefore, even if there is variation in the dielectric constant ε of the printed circuit board 10, impedance matching can be easily achieved.

[0030] In other words, the usable frequency band can be broadened by the operation of first parasitic element 25 and second parasitic element 26 as resonating elements, which will be described later, or by cooperation between these and a characteristic impedance matching means that allows fine adjustment of reactance matching in stages. This is one of the reasons why sufficient antenna characteristics can be obtained in the quasi-millimeter wave band even if a general-purpose and inexpensive FR-4 board is used as printed circuit board 10 and the width of feed line 22 is increased.

[0031] The first ground element 23 and the second ground element 24 also have a long side with a length L that acts as a reflector for the radiating element 21 at the operating frequency. 231Therefore, it operates to reflect radiation from the radiating element 21 toward the feed line 22, and can prevent unnecessary radiation from the feed line 22. In addition, it is possible to suppress distortion of the radiation pattern and reduction in radiation gain caused by other high-frequency components present in the direction of the feed line 22.

[0032] A first parasitic element 25 extends from the first ground element 23 so as to surround a part of the radiating element 21. Here, the first parasitic element 25 is arranged so as to surround the radiating element 21 in a substantially L-shape. The base end of this first parasitic element 25 is integrated with the first ground element 23 at a position slightly closer to the feed line 22 than the feed element 21 and slightly away from the outer edge of the radiating element 21. The first parasitic element 25 extends from the base end along the outer edge shape of the radiating element 21 in parallel with an extension of the central axis of the feed line 22 in a plan view, approximately the length L of the short side of the first ground element 23. 232 As the outer edge shape of the radiating element 21 changes by approximately 90 degrees, the first parasitic element 25 also changes direction and extends in an L-shape, and its tip becomes an open end. 253 In this example, it is 1.6 mm, but it is not limited to this.

[0033] Further, from the second ground element 24, the second parasitic element 26 extends in an L-shape as viewed from above so as to surround the radiating element 21 from the opposite direction to the first parasitic element 25. A gap D is provided between the open ends of the first parasitic element 25 and the second parasitic element 26. 25 They face each other with a gap D 25 The midpoint of is on an extension of the central axis of the feeder line 22.

[0034] First parasitic element 25 is conductive with first ground element 23. Moreover, second parasitic element 26 is conductive with second ground element 24. Furthermore, first ground element 23 and second ground element 24 are conductive with the ground plane on the back surface of printed circuit board 10. Therefore, first parasitic element 25 and second parasitic element 26 also function as a signal phase adjuster of radiating element 21, which will be described later.

[0035] The first parasitic element 25 and the second parasitic element 26 also function as resonant elements for multiple resonance. That is, a high-frequency ground current flows through each of the parasitic elements 25 and 26, and is inductively coupled with the radiating element 21, exciting the resonant frequency of the radiating element 21. Each of the parasitic elements 25 and 26 has a length (L) at which it resonates at a used frequency other than the center frequency of the 28 GHz band. 251 (In this example, 5mm) + L 252 (In this example, it is set to 2.7 mm). The effect of multiple resonance between the radiating element 21 and each of the parasitic elements 25 and 26 makes it possible to widen the usable frequency band. Also, the gain can be increased.

[0036] Each of the parasitic elements 25 and 26 further has a length L 252 is designed to be slightly shorter than half the wavelength of the 28 GHz band. As a result, the portions of each of the parasitic elements 25, 26 that are approximately parallel to the long sides of the first ground element 23 and the second ground element 24 act as directors. Therefore, the radiation pattern from the radiating element 21 can be tilted in the opposite direction to the first ground element 23 and the second ground element 24.

[0037] Although the first ground element 23 and the first parasitic element 25 have different shapes, they are in a positional relationship (including size) that is symmetrical in terms of high frequency current when viewed from the feeding point 211 (null point). That is, the electric fields and the magnetic fields at the feeding point 211 are balanced. The first ground element 23 and the first parasitic element 25 are also in a positional relationship (including the distance from the radiating element 21) that is symmetrical in terms of high frequency current between the radiating element 21 and the first ground element 23. Therefore, the electric fields and the magnetic fields at the feeding point 211 are balanced not only between the first ground element 23 and the parasitic element 25 but also including the radiating element 21. Such a positional relationship is similar between the second ground element 24 and the second parasitic element 26, and between the second ground element 24, the second parasitic element 26 and the radiating element 21. As described above, the first ground element 23 and the second ground element 24 are arranged symmetrically with respect to the central axis of the feed line 22, and the first parasitic element 25 and the second parasitic element 26 are arranged symmetrically with respect to each other. That is, the first ground element 23 and the second ground element 24, and the first parasitic element 25 and the second parasitic element 26 are structurally symmetrically positioned. This eliminates the imbalance of the high-frequency current at the feed point 211 in the planar antenna 1, and ensures stable operation. At this time, the radiation near the feed point 211 becomes a null point like a dipole antenna.

[0038] Next, the sheet metal element 27 will be described in detail. The sheet metal element 27 has a width (short side) W 27 The base end of the radiating element 21 is soldered to the surface of the radiating element 21 at a height H 27 After protruding vertically upward by a distance of 1.8 mm (in this example), the direction is changed at an acute angle at the bending point, and the length L 27 (3.5 mm) so that the tip becomes the free end. Line width W of sheet metal element 27 27 is set to be equal to or slightly narrower than the long side of radiating element 21. This is to make the free end of sheet metal element 27 act as a director for radiating element 21. The direction is changed at an acute angle at the bending point because this makes design easier. A portion of the free end overlaps with part of the open end of first parasitic element 25 and part of the open end of second parasitic element 26 when viewed from above. This results in a structure in which capacitive reactance occurs due to electric field coupling.

[0039] The sheet metal element 27 acts as an adjuster for the signal phase of the radiating element 21, and also acts as a director and as an adjustment element for the directivity and tilt angle of the radiation pattern. That is, in order to stably maintain the VSWR characteristics and directional characteristics of the planar antenna 1 or to increase the drop (attenuation) of the NULL point, it is necessary to more reliably balance the high frequency current. The balance of the high frequency current can be adjusted by changing the shape of each of the ground elements 23, 24. However, the radiating element 21 is a microstrip (patch), and changing the shape or size of any part of the radiating element 21 or each of the ground elements 23, 24 requires a chain reaction of changing the shapes of the other parts as well. For this reason, the above adjustment is actually difficult.

[0040] The sheet metal element 27 has a length L 27 By simply changing the capacitance reactance generated by the electric field coupling between the free end and the open ends of each of the parasitic elements 25 and 26, the sheet metal element 27 can be used as a means for adjusting the signal phase. Therefore, the use of the sheet metal element 27 makes it easy to adjust the balance of the high-frequency current. In addition, the length L of the sheet metal element 27 27 By changing the position of the director, the vector of the high frequency current and the position of the director change. Therefore, by using the sheet metal element 27, it becomes easy to control the tilt angle of the radiation pattern. According to the experiment by the inventor, it has been found that the tilt angle can be changed up to about 30 degrees as long as it is based on the size and arrangement shown in FIG.

[0041] An example of frequency-VSWR characteristics of the planar antenna 1 of the first embodiment is shown in Fig. 3. Fig. 3 shows the output result of a simulator based on the material, shape, size, and arrangement of each of the above-mentioned components. Fig. 3 shows that the planar antenna 1 has a VSWR of 2 or less in the 28 GHz band (26.5 GHz to 29.5 GHz). This is believed to be mainly because the first ground element 23 and the second ground element 24 operate effectively as an impedance matching means for the feed line 22, and the first parasitic element 25 and the second parasitic element 26 operate effectively as a resonating element for the radiating element 21.

[0042] As described above, the planar antenna 1 of this embodiment uses a general-purpose and inexpensive FR-4 substrate, has a structure that allows for easy impedance matching and fine adjustment, and is a low-cost antenna with sufficient mechanical strength, yet can ensure stable gain over a wide bandwidth of 3 GHz or more in the 28 GHz band.

[0043] Next, the radiation pattern of the planar antenna 1 will be examined. Fig. 4 is a diagram showing the output result of a simulator based on the material, shape, size, and arrangement of each of the above-mentioned components. For convenience, three orthogonal axes, the X-axis, the Y-axis, and the Z-axis, are defined in Fig. 4. In these three orthogonal axes, the +Z direction is vertically upward from the feed point 211, the +X direction is the direction from the feed point 211 toward the nearest first parasitic element 25, the -X direction is the direction from the feed point 211 toward the nearest second parasitic element 26, and the +Y direction is the direction from the feed point 211 toward the gap D 25 The -Y direction is the direction toward the midpoint of the power supply line 211, and the -Y direction is the direction from the power supply point 211 toward the power supply line 22.

[0044] For convenience, in this specification, the surface of printed circuit board 10 viewed from above is referred to as the "XY surface," the surface of printed circuit board 10 viewed from the side (short side) is referred to as the "YZ surface," and the surface of printed circuit board 10 viewed from the front (long side) of power supply point 211 from the direction of power supply line 22 is referred to as the "XZ surface."

[0045] In FIG. 4, the top view image and the side view image show the radiation pattern from the radiating element 21. The left diagram of FIG. 4 is a diagram visualizing the spread and the magnitude of the electric field strength. In the diagram, the larger the spread, the broader the range in which the electric field strength occurs, and the darker the color, the stronger the electric field strength. The right diagram of FIG. 4 shows the radiation gain characteristics. In the diagram, the radiation pattern on the XZ plane is set to 0 degrees from the power supply point 211 in the +Z direction on the XZ plane, and the relative radiation gain magnitude (dBi) is shown as 0.00, -10.00 (dBi), and -20.00 (dBi) in the range from this 0 degree centered on the +X direction to -90 degrees in -5 degree increments, and in the range from this 0 degree centered on the -X direction to +90 degrees in +5 degree increments. The radiation pattern in the YZ plane is set to 0 degrees in the +Z direction from feed point 211 on the YZ plane, and the relative radiation gain magnitude (dBi) is shown by concentric dashed lines as 0.00, -10.00 (dBi), and -20.00 (dBi) in the range from 0 degrees in the +Y direction to -90 degrees in -5 degree increments, and in the range from -Y direction to +90 degrees in +5 degree increments.

[0046] Referring to FIG. 4, the radiation pattern of the planar antenna 1 spreads almost evenly in the +X and -X directions on the XZ top surface, but the radiation gain drops relatively significantly in the vicinity of the feeder line 22. That is, the radiation gain drops sharply. Also, as shown in the top view image and the radiation pattern on the XZ surface, the spread of the radiation pattern is narrowed to a beam shape compared to the +Z direction, +Y direction, and -Y direction, and the radiation gain is high. Furthermore, as shown in the side view image and the radiation pattern on the YZ surface, the part on the YZ surface where the radiation gain is high is tilted in the +Y direction. That is, the radiation pattern is tilted in the +Y direction. Since the radiation pattern does not tilt in the -Y direction, it can be seen that unwanted radiation from the feeder line 22 and the influence on the subsequent stage are close to zero.

[0047] The radiation pattern does not tilt in the -Y direction because first ground element 23 and second ground element 24 act as reflectors for radiating element 21, and the +Y direction side portion of first parasitic element 25, the +Y direction side portion of second parasitic element 26, and the open end of sheet metal element 27 act as directors for radiating element 21. The tilt angle is determined by the length L of the sheet metal element 27. 27 and height H 27 This can be (easily) adjusted by changing the magnitude of capacitive coupling between the open ends of first parasitic element 25 and second parasitic element 26. Alternatively, this can be (easily) adjusted by changing the size of each of ground elements 23, 24 to change the direction of the vector of the high-frequency current.

[0048] The radiation pattern spreads almost evenly in the +X and -X directions with radiating element 21 as the center, and the beam is narrowed and tilted, because first ground element 23, second ground element 24, first parasitic element 25, second parasitic element 26, and sheet metal element 27 around radiating element 21 are arranged in the shapes and sizes shown in Figure 2. Moreover, the reason why the radiation gain is relatively small near the feed line 22 is because the feed point 211 is set as the NULL point of the radiating element 21. The radiation pattern in the XY plane can be adjusted by changing the gap between the radiating element 21 and the first parasitic element 25 and the second parasitic element 26, etc. Thus, the fact that the printed circuit board 10 has little effect on the radiation pattern is one of the reasons why the printed circuit board 10 can be made of a general-purpose, inexpensive FR-4 board.

[0049] [Comparative Example] In order to verify in more detail the action and effect of each component of planar antenna 1, the inventor separately created a planar antenna of comparison example 1 in which some of the components were removed, and simulated the operation of this planar antenna under conditions that were the same as those of planar antenna 1 in terms of material, size, and arrangement.

[0050] Fig. 5 is a diagram showing the radiation pattern of the planar antenna of Comparative Example 1. The top view image and side view image are diagrams that visualize the spread of the radiation pattern from the radiation element and the magnitude of the electric field intensity, and the way of viewing the radiation pattern in the YZ plane is the same as Fig. 4. This planar antenna of Comparative Example 1 is a planar antenna configured without the sheet metal element 27. In Fig. 5, the radiation pattern in the XZ plane shown in Fig. 4 is omitted, but this is because no significant difference was observed in the radiation pattern in the XZ plane even in a configuration without sheet metal element 27. The reason why no significant difference was observed is thought to be due to the fact that feed point 211 is set as the NULL point of radiating element 21, and that feed line 22, first ground element 23, and second ground element 24 are used as impedance matching means.

[0051] A notable difference with the planar antenna 1 is the radiation pattern in the YZ plane. That is, in the planar antenna of the comparative example 1, the beam narrowing in the +Y direction is looser than in the planar antenna 1, and the drop at the NULL point is smaller. In addition, the spread of the radiation pattern near the feed point is broader than that of the planar antenna 1, and as shown in the side view image, the spread of the radiation pattern in the -Y direction is slightly closer to the feed line 22. This is because the planar antenna of the comparative example 1 does not have the fine phase adjustment and director operation by the sheet metal element 21. On the other hand, this fact means that the sheet metal element 27 of the planar antenna 1 plays a large role in phase adjustment and acting as a director. In the planar antenna of Comparative Example 1, the direction in which the radiation gain is greatest is still tilted toward the +Y direction. This is because first ground element 23 and second ground element 24 act as reflectors for radiating element 21, suppressing radiation in the directions of first ground element 23 and second ground element 24. Also, this is because the side surface of first parasitic element 25 in the +Y direction and the side surface of second parasitic element 26 in the +Y direction act as directors for radiating element 21.

[0052] Next, a planar antenna of Comparative Example 2 will be described. The planar antenna of Comparative Example 2 is a planar antenna that does not include the first parasitic element 25 and the second parasitic element 26, in addition to the sheet metal element 27. Fig. 6 is a diagram showing the radiation pattern of the planar antenna of Comparative Example 2. The top view image and the side view image are diagrams that visualize the spread of the radiation pattern from the radiation element and the magnitude of the electric field intensity, and the way of viewing the radiation pattern in the YZ plane is the same as Fig. 4.

[0053] In Fig. 6, the radiation gain characteristics in the XZ plane shown in Fig. 4 are omitted because no significant difference was observed in the radiation pattern in the XZ plane. This fact is also due to the fact that feed point 211 is set as the NULL point of radiating element 21, and that feed line 22, first ground element 23, and second ground element 24 are used as impedance matching elements.

[0054] A remarkable difference was observed in the radiation pattern in the YZ plane, as in the example shown in FIG. 5. That is, as shown in the top view image of FIG. 6, in the planar antenna of Comparative Example 2, the beam is not narrowed, the radiation gain is reduced, and the spread of the radiation pattern is broad in all directions, including the +X direction, the -X direction, the +Y direction, and the -Y direction. In addition, the spread of the radiation pattern is significantly wider in the direction of the feed line 22 than in the example of FIG. 5. This is because the balance of the high-frequency current in the ground is greatly disrupted, the drop of the NULL point is smaller, and the radiation in the -Y direction is stronger. In addition, the YZ plane is not narrowed because the first parasitic element 25 and the second parasitic element 26 do not act as directors. In other words, this fact means that the role of the +Y direction side surfaces of the first parasitic element 25 and the second parasitic element 26 of the planar antenna 1, which act as directors, is particularly large.

[0055] In the case of a general planar antenna having directivity in the +Z direction, in an environment in which there are no high-frequency components other than the radiating element on the printed circuit board 50 on which the radiating element is patterned, the radiation pattern 70 shown in Fig. 7A will result. When another high-frequency component 60 is placed on the printed circuit board 50, the radiation pattern 71 will be drawn to the high-frequency component 60, as shown in Fig. 7B. When the high-frequency component 60 is covered with a shielding material, this tendency becomes more pronounced. This also applies when another high-frequency component is present in the vicinity of the planar antenna 1 of the first embodiment. In this case, if the size of sheet metal element 27 is changed in advance to tilt the radiation pattern in the opposite direction to the direction in which the high-frequency components are located, the effect of the radiation pattern being attracted to the high-frequency components can be mitigated.

[0056] In this manner, in the first embodiment, since the FR-4 board used as the printed circuit board 10 has high loss in the 28 GHz band, its size is made as small as possible, and measures are taken to reduce unwanted radiation, improve directivity, and adjust phase to increase the radiation gain to a practical level.

[0057] To prevent unwanted radiation, the conductive pattern is made symmetrical at the feed point 211 so that the vicinity of the feed point 211 becomes a null point. However, doing so raises the risk that the radiation pattern will be pulled in the +X and -X directions (the radiation pattern will be split), and furthermore, there is a risk that part of the radiation pattern will leak in the -Y direction. Therefore, in the planar antenna 1 of the first embodiment, the first ground element 23 and the second ground element 24 are designed to also function as reflectors for the radiating element 21, thereby eliminating unnecessary radiation (radiation loss) from the feed line 22 and preventing the radiation pattern from being broken.

[0058] To improve directivity, the director effect is utilized. That is, in the planar antenna 1 of the first embodiment, a part of the first parasitic element 25 and a part of the second parasitic element 26, and the free end of the sheet metal element 27 are made to act as directors for the radiating element 21, narrowing the radiation pattern from the radiating element 21 into a beam shape, and the further narrowed radiation pattern is made to tilt in the +Y direction.

[0059] The phase adjustment measure is a measure to solve the adjustment problem that may occur due to the first ground element 23, the second ground element 24, the first parasitic element 25, the second parasitic element 26, and the sheet metal element 27 being placed close to the periphery of the radiating element 21. In the general idea in the high frequency band, conductive elements that induce high frequency currents (including vector components) are not placed close to the radiating element 21. However, in the planar antenna 1 of the first embodiment, the signal phase can be adjusted by the reactance due to the electric field coupling generated between the tip of the sheet metal element 27 and the open end of the first parasitic element 25 and the open end of the second parasitic element 26, and since there are two parasitic elements, the effect on each parasitic element can be reduced.

[0060] In this way, the planar antenna 1 of the first embodiment operates as a composite antenna that is based on a magnetic current (magnetic field) antenna and incorporates the design concept of an electric field antenna.

[0061] [Second embodiment] 8 is a diagram showing a part of the configuration of a planar antenna 2 according to a second embodiment of the present invention, and shows only the parts that are different from the first embodiment. The same components as those described in the first embodiment are given the same reference numerals, and the description thereof will be omitted. In this planar antenna 2, a transmission line 32 passes between the open end of the first parasitic element 25 and the open end of the second parasitic element 26. This transmission line 32 extends from the radiating element 21 as its base end, and its terminal end is conductively connected to the second radiating element 33. The second radiating element 33 has the same shape and size as the radiating element 21. The second radiating element 33 also forms an array structure with the radiating element 21. The length of the transmission line 32 is approximately half the wavelength of the frequency used. The width of the transmission line 32 is approximately equal to the line width W of the feed line 22 connected to the feed point 211.223 is equal to or thinner than

[0062] This planar antenna 2 can achieve a higher gain than the planar antenna 1 by combining the phases of the radiating element 21 and the second radiating element 33. The planar antenna 2 can also further narrow the radiation pattern in the +Y direction. Although the sheet metal element 27 is omitted in FIG. 8, the configuration may include the sheet metal element 27, as in the planar antenna 1. The second radiating element 33 is not limited to having the same shape and size as the radiating element 21. The second radiating element 33 may have any shape and size that radiates radiation in the same manner as the radiating element 21 and allows adjustment of the signal phase and impedance matching.

[0063] [Third embodiment] 9 is a diagram showing a part of the configuration of a planar antenna 3 according to a third embodiment of the present invention, and shows only the parts that are different from the first embodiment. The same components as those described in the first embodiment are given the same reference numerals, and the description thereof will be omitted. In this planar antenna 3, a plurality of auxiliary parasitic elements 36, 37 are present on the opposite side of the radiating element 21, with the open end of the first parasitic element 25 and the open end of the second parasitic element 26 as the center. The plurality of auxiliary parasitic elements 36, 37 are slightly shorter in size than the length of the side surface of the first parasitic element 25 and the side surface of the second parasitic element 26 in each +Y direction. The plurality of auxiliary parasitic elements 36, 37 are disposed in the same plane as the radiating element 21 and the side surfaces of the first parasitic element 25 and the second parasitic element 26 in each +Y direction.

[0064] Moreover, auxiliary parasitic element 36 is arranged in the +Y direction from the +Y side surface of first parasitic element 25 at a position where it acts as a director for radiating element 21. Auxiliary parasitic element 37 is arranged in the +Y direction from the +Y side surface of second parasitic element 26 at a position where it acts as a director for radiating element 21. The above positions are approximately 1 / 4 or 1 / 8 of the wavelength λ of the frequency used.

[0065] In this planar antenna 3, the electric field strength in the +Y direction is further strengthened, and the tilt angle can be made larger. Although the sheet metal element 27 is omitted in Fig. 9, the sheet metal element 27 may be present as in the planar antenna 1. Although two auxiliary parasitic elements 36 and 37 are shown in Fig. 9, the number of auxiliary parasitic elements may be one or three or more as long as the conditions for operating as a director are satisfied. Furthermore, the shape of the auxiliary parasitic elements 36 and 37 may be rectangular or trapezoidal as long as the conditions for operating as a director are satisfied.

[0066] [Other embodiments] In the first to third embodiments, examples have been described in which the present invention is applied to planar antennas 1, 2, and 3 that can be used in the 28 GHz band (26.5 GHz to 29.5 GHz). However, by changing the size and spacing of each component, the present invention can be embodied as a planar antenna that can be used in the 26 GHz band (24.25 to 27.5 GHz) or other frequency bands.

[0067] In the first to third embodiments, an example has been described in which an FR-4 board is used as the printed circuit board 10, but boards of grades FR-1, FR-2, FR-3, and FR-5 may also be used. Also, a ceramic board (alumina), a multilayer board, etc. may also be used.

[0068] Furthermore, the planar antennas 1, 2, and 3 of the first to third embodiments can be implemented as one high-frequency module usable in the quasi-millimeter wave band together with, for example, an RF detector or other high-frequency components.

[0069] [Field of use] The planar antennas 1, 2, and 3 of the first to third embodiments are expected to be applied as antenna devices in various fields, such as surveillance (security and nursing care), IoT (content distribution, etc.), AI (autonomous driving, etc.), and medicine and healthcare.

[0070] According to the present specification, the following aspects are provided. (Aspect 1) A first aspect is a planar antenna formed on a surface of a substrate whose back surface is a ground surface, The planar antenna comprises a radiating element, a feed line connected to the radiating element, a first ground element and a second ground element each electrically connected to the ground plane and arranged to face each other across the feed line, a first parasitic element extending from the first ground element to surround at least a portion of the radiating element, and a second parasitic element extending from the second ground element in a direction opposite to the first parasitic element to surround at least a portion of the radiating element, wherein the first ground element and the second ground element operate as an impedance matching device for the feed line, and the first parasitic element and the second parasitic element operate as an adjuster for a signal phase of the radiating element. According to the first aspect, the first ground element and the second ground element act as impedance matching elements for the adjacent radiating element, and also act as characteristic impedance changing parts that enable impedance matching over a wide band. Therefore, even if there is variation in the dielectric constant of the substrate, impedance matching can be easily achieved. Furthermore, since the first parasitic element and the second parasitic element act as resonating elements, they are inductively coupled with the radiating element and multi-resonate. Due to the effect of this multi-resonance, the usable frequency band can be widened. Also, the gain can be increased. As a result, a planar antenna that can obtain sufficient antenna characteristics in the quasi-millimeter wave band at low cost can be realized even if a general-purpose and inexpensive FR-4 substrate is used as the substrate and the width of the feed line is increased.

[0071] (Aspect 2) Aspect 2 is the planar antenna according to aspect 1, wherein the first ground element and the second ground element also act as reflectors for the radiating element. According to the second aspect, it is possible to prevent unwanted radiation from the power feed line, and also to suppress distortion of the radiation pattern and reduction in radiation gain caused by other high-frequency components present in the direction of the power feed line.

[0072] (Aspect 3) A third aspect of the planar antenna according to the first or second aspect is a planar antenna according to the first or second aspect, in which the first parasitic element and the second parasitic element also function as directors for the radiating element. According to the third aspect, the radiation pattern from the radiating element can be tilted, and the tilt angle of the radiation pattern can be controlled.

[0073] (Aspect 4) A fourth aspect of the present invention is the planar antenna according to any one of the first to third aspects, in which the feed line is a planar line, the width of which is smallest at a portion where the feed line is connected to the radiating element. According to the fourth aspect, it is possible to finely adjust the impedance matching, and it is also possible to eliminate unnecessary reflections between the radiating element and the feed line.

[0074] (Aspect 5) A fifth aspect of the present invention is the planar antenna according to the fourth aspect, wherein the characteristic impedance of the feed line is greatest at a connection point with the radiating element. According to the fifth aspect, fine adjustment for characteristic impedance matching becomes easy.

[0075] (Aspect 6) A sixth aspect of the present invention is the planar antenna according to the fourth or fifth aspect, wherein the connection portion is a null point of the radiating element. According to the sixth aspect, even if the width of the feed line increases due to the thicker substrate, or the dielectric constant of the substrate varies, which may cause matching difficulties, the effect on the antenna characteristics (VSWR, directivity, etc.) caused by such a problem can be minimized. In addition, unnecessary radiation from the feed line can be prevented. This allows the use of inexpensive FR-4 substrates even in high frequency bands such as the quasi-millimeter wave band or higher.

[0076] (Aspect 7) A seventh aspect is a planar antenna according to any one of the first to sixth aspects, wherein the radiating element itself resonates at a first frequency and multi-resonates between the first parasitic element and the second parasitic element at a second frequency different from the first frequency. According to the seventh aspect, the usable frequency band can be broadened and the gain can be increased by the effect of multiple resonance. As a result, even if a general-purpose and inexpensive FR-4 board is used as the board and the width of the feed line is increased, a planar antenna that can obtain sufficient antenna characteristics in the quasi-millimeter wave band can be obtained at low cost.

[0077] (Aspect 8) An eighth aspect of the planar antenna according to any one of the first to seventh aspects, wherein the shapes and positions of the radiating element and the feed line are symmetrical with respect to the central axis of the feed line, and the positions of the first ground element and the first parasitic element and the positions of the second ground element and the second parasitic element are symmetrical with respect to the central axis of the feed line. According to the eighth aspect, the high frequency current at the feeding point is prevented from becoming unbalanced, and the operation can be stabilized.

[0078] (Aspect 9) A ninth aspect is a planar antenna described in any one of the first to eighth aspects, in which the first parasitic element and the second parasitic element each have an open end that faces each other at a predetermined distance, and a portion of the open end that is approximately parallel to the radiating element is positioned so as to act as the director of the radiating element. According to the ninth aspect, the radiation pattern from the radiating element can be tilted, which makes it easier to control the tilt angle of the radiation pattern.

[0079] (Aspect 10) A tenth aspect is the planar antenna according to the ninth aspect, in which a transmission line extending from the radiating element as its base end passes between the open end of the first parasitic element and the open end of the second parasitic element, and an end of the transmission line is conductively connected to the second radiating element. According to the tenth aspect, the first radiating element and the second radiating element form an array antenna structure. This can increase the radiation gain. Also, the radiation pattern in the Y direction can be narrowed.

[0080] (Aspect 11) An eleventh aspect is a planar antenna as described in an tenth aspect, in which at least one auxiliary parasitic element acting as a director for the radiating element is located on the opposite side of the radiating element, centered on the open end of the first parasitic element and the open end of the second parasitic element. According to the eleventh aspect, the radiation pattern from the radiating element can be tilted, which makes it easier to control the tilt angle of the radiation pattern.

[0081] (Aspect 12) A twelfth aspect is a planar antenna described in any one of aspects 9 to 11, in which a sheet metal element whose ends are capacitively coupled to the open end of the first parasitic element and the open end of the second parasitic element is conductively connected to the surface of the radiating element. According to the twelfth aspect, the sheet metal element is capacitively coupled to the open end of the first parasitic element and the open end of the second parasitic element. Therefore, the sheet metal element operates as an adjuster of the signal phase of the radiating element. This operation of the sheet metal element makes it possible to adjust the signal phase simply by changing the capacitive reactance of the capacitive coupling. This makes it easy to adjust the balance of the high-frequency current.

[0082] (Aspect 13) Example 13 is the planar antenna of Example 12, wherein the sheet metal element acts as a director for the radiating element. According to the thirteenth aspect, the radiation pattern from the radiating element can be tilted, which makes it easier to control the tilt angle of the radiation pattern.

[0083] (Aspect 14) A fourteenth aspect is a high-frequency module including an antenna portion present on the surface of a substrate whose back surface is a ground conductor, the antenna portion being any of the planar antennas of aspects 1 to 13, and the planar antenna being sized to operate in a frequency band of 26 GHz or higher. According to the fourteenth aspect, a high-frequency module that can be used in the quasi-millimeter wave band can be obtained at low cost.

Claims

1. A planar antenna formed on a surface of a substrate whose rear surface is a ground surface, A radiating element; A feed line connected to the radiating element; a first ground element and a second ground element, each of which is electrically connected to the ground plane and is disposed opposite to each other with the power supply line therebetween; a first parasitic element extending from the first ground element so as to surround at least a portion of the radiating element; a second parasitic element extending from the second ground element in a direction opposite to the first parasitic element so as to surround at least a part of the radiating element, the first ground element and the second ground element operate as an impedance matching device for the feed line, the first parasitic element and the second parasitic element operate as an adjuster for a signal phase of the radiating element, and A planar antenna, wherein the first ground element and the second ground element act as reflectors for the radiating element.

2. A planar antenna formed on a surface of a substrate whose rear surface is a ground surface, A radiating element; A feed line connected to the radiating element; a first ground element and a second ground element, each of which is electrically connected to the ground plane and is disposed opposite to each other with the power supply line therebetween; a first parasitic element extending from the first ground element so as to surround at least a portion of the radiating element; a second parasitic element extending from the second ground element in a direction opposite to the first parasitic element so as to surround at least a part of the radiating element, the first ground element and the second ground element operate as an impedance matching device for the feed line, the first parasitic element and the second parasitic element operate as an adjuster for a signal phase of the radiating element, and A planar antenna, wherein the first parasitic element and the second parasitic element act as directors for the radiating element.

3. the feed line is a planar line, and the width of the feed line at the connection portion with the radiating element is smaller than the width of other portions of the feed line; 3. A planar antenna according to claim 1 or 2.

4. The characteristic impedance of the feed line is the largest at a connection point with the radiating element. A planar antenna according to any one of claims 1 to 3.

5. The connection portion is a region in the radiating element where high frequency current is cancelled.

5. A planar antenna according to claim 4.

6. 6. The planar antenna according to claim 1, wherein the radiating element itself resonates at a first frequency, and multi-resonates between the first parasitic element and the second parasitic element at a second frequency different from the first frequency.

7. the shapes and positions of the radiating element and the feed line are symmetrical with respect to a central axis of the feed line; the first ground element and the first parasitic element are disposed symmetrically with respect to a central axis of the feed line, and the second ground element and the second parasitic element are disposed symmetrically with respect to a central axis of the feed line. A planar antenna according to any one of claims 1 to 6.

8. the first parasitic element and the second parasitic element each have an open end that faces each other at a predetermined distance; 8. A planar antenna as claimed in claim 2 or any one of claims 3 to 7 depending on claim 2, wherein a part of the open end which is substantially parallel to the radiating element is positioned so as to act as the director of the radiating element.

9. 9. The planar antenna according to claim 8, wherein a transmission line extending from the radiating element as a base end passes between the open end of the first parasitic element and the open end of the second parasitic element, and an end of the transmission line is conductively connected to the second radiating element.

10. 10. The planar antenna according to claim 9, wherein at least one auxiliary parasitic element acting as a director for the radiating element is located on the opposite side to the radiating element with respect to the open end of the first parasitic element and the open end of the second parasitic element as a center.

11. A sheet metal element having an end portion, the end portion is capacitively coupled to an open end of the first parasitic element and an open end of the second parasitic element, The sheet metal element is conductively connected to a surface of the radiating element. A planar antenna according to any one of claims 8 to 10.

12. the sheet metal element acts as a director for the radiating element; A planar antenna according to claim 11.

13. A high-frequency module including an antenna portion on a surface of a substrate whose rear surface is a ground conductor, The antenna portion is a planar antenna according to any one of claims 1 to 12, The planar antenna is sized to operate in a frequency band of 26 GHz or higher. High frequency module.

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