Feeding apparatus and low noise block down-converter

A feeding apparatus includes a substrate, an annular grounded metal sheet having a first opening and a second opening, a rectangular grounded metal sheet extending from the annular grounded metal sheet toward an interior according to a configuration of a septum polarizer of a waveguide, a first parasitic grounded metal sheet extending from a side of the rectangular grounded metal sheet along a first direction, a second parasitic grounded metal sheet extending from another side of the rectangular grounded metal sheet along a second direction, a first feeding metal sheet extending from the first opening toward the interior and including a first portion, a second portion and a third portion and a second feeding metal sheet extending from the second opening toward the interior and including a fourth portion, a fifth portion and a sixth portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a feeding apparatus and a low noise block down-converter for a waveguide, and more particularly, to a feeding apparatus and a low noise block down-converter, which can simultaneously modify impedance matching at high frequencies and low frequencies and reduce return loss.

2. Description of the Prior Art

Satellite communication has the advantage of wide communication coverage and being free from interference from ground environment, and is widely used for military communication, exploration and business communication services such as satellite navigation, satellite voice broadcast and satellite television broadcast. A conventional satellite communication receiving device consists of a dish reflector and a low noise block down-converter. The low noise block down-converter is disposed at the focus of the dish reflector. After the low noise block down-converter receives radio signals reflected from dish reflector, the low noise block down-converter converts the radio signals down to middle band, and then transmits the radio signals to a back-end radio frequency processing unit for signal processing, thereby providing satellite television programs to users.

Please refer toFIG. 1Athat is a schematic diagram illustrating a conventional low noise block down-converter10for satellite communication. The low noise block down-converter10can be disposed at the focus of a dish reflector to collect radio signals reflected by the dish reflector. As shown inFIG. 1A, the low noise block down-converter10consists of a feedhorn12, a waveguide14, a septum polarizer16and a feeding apparatus100. The septum polarizer16is fixed in the waveguide14with a cylindrical shape, and divides the interior of the waveguide14in half.FIG. 1Bis a schematic diagram illustrating a top view of a front surface of the conventional feeding apparatus100. The feeding apparatus100is utilized to transmit the radio signals received by the feedhorn12to a back-end radio frequency processing unit, and consists of a substrate110, an annular grounded metal sheet120, a rectangular grounded metal sheet130, feeding metal sheets140a,140band signal wires150a,150b.

Conventionally, in order to adjust operating frequency range of the low noise block down-converter10, lengths of the feeding metal sheets140a,140bare modified to control impedance of the feeding apparatus100so that impedance matching may be achieved with sufficient bandwidth. In practice, however, failures frequently occur—there exists a tradeoff among frequencies. Specifically, please refer toFIG. 1C, which is a schematic diagram illustrating return loss of the feeding apparatus100in Ku band (10.7 GHz-12.75 GHz). As shown inFIG. 1C, the return loss of the feeding apparatus100is low, merely in a range of 11.00 GHz to 12.00 GHz, while the return loss of the feeding apparatus100from 10.7 GHz to 11.00 GHz and from 12.00 GHz to 12.75 GHz is quite high and grows rapidly. Therefore, the feeding apparatus100cannot optimize return loss at high frequencies and low frequencies at the same time. Along with the growing needs for satellite television, the number of frequency bands covered by direct broadcast satellites is increasing; as a result, there is an urgent need for improvement in the field.

SUMMARY OF THE INVENTION

It is therefore one of the objectives of the present invention to provide a feeding apparatus and a low noise block down-converter to effectively modify impedance matching at high frequencies and low frequencies and reduce return loss.

An embodiment of the invention provides a feeding apparatus adapted to a waveguide. The feeding apparatus comprises a substrate; an annular grounded metal sheet, disposed on the substrate, substantially in a shape of an annularity, and having a first opening and a second opening; a rectangular grounded metal sheet, disposed on the substrate, extending from the annular grounded metal sheet across an interior of the annularity and corresponding to a configuration of a polarizer of the waveguide; a first parasitic grounded metal sheet, extending from a side of the rectangular grounded metal sheet along a first direction; a second parasitic grounded metal sheet, extending from another side of the rectangular grounded metal sheet along a second direction, wherein the second direction is substantially opposite to the first direction; a first feeding metal sheet, extending from the first opening toward the interior of the annularity and comprising a first portion, a second portion and a third portion, wherein a width of the first portion is different from a width of the second portion, and the width of the second portion is different from a width of the third portion; and a second feeding metal sheet, extending from the second opening toward the interior of the annularity and comprising a fourth portion, a fifth portion and a sixth portion, wherein a width of the fourth portion is different from a width of the fifth portion, and the width of the fifth portion is different from a width of the sixth portion.

Another embodiment of the invention provides a low noise block down-converter adapted to a communication receiving device. The low noise block down-converter comprises a feedhorn, a waveguide, a polarizer, and a feeding apparatus. The feeding apparatus comprises a substrate; an annular grounded metal sheet, disposed on the substrate, substantially in a shape of an annularity, and having a first opening and a second opening; a rectangular grounded metal sheet, disposed on the substrate, extending from the annular grounded metal sheet across an interior of the annularity and corresponding to a configuration of a polarizer of the waveguide; a first parasitic grounded metal sheet, extending from a side of the rectangular grounded metal sheet along a first direction; a second parasitic grounded metal sheet, extending from another side of the rectangular grounded metal sheet along a second direction, wherein the second direction is substantially opposite to the first direction; a first feeding metal sheet, extending from the first opening toward the interior of the annularity and comprising a first portion, a second portion and a third portion, wherein a width of the first portion is different from a width of the second portion, and the width of the second portion is different from a width of the third portion; and a second feeding metal sheet, extending from the second opening toward the interior of the annularity and comprising a fourth portion, a fifth portion and a sixth portion, wherein a width of the fourth portion is different from a width of the fifth portion, and the width of the fifth portion is different from a width of the sixth portion.

DETAILED DESCRIPTION

Please refer toFIG. 2.FIG. 2is a schematic diagram illustrating a top view of a front surface of a feeding apparatus20according to an embodiment of the present invention. The feeding apparatus20may replace the feeding apparatus100inFIGS. 1A and 1Band be implemented in the low noise block down-converter10to transmit radio frequency signals received by the feedhorn12to the back-end radio frequency processing unit. The feeding apparatus20comprises a substrate200, an annular grounded metal sheet202, a rectangular grounded metal sheet204, feeding metal sheets206,208, signal wires210,212and parasitic grounded metal sheets214,216. The annular grounded metal sheet202, the rectangular grounded metal sheet204, the feeding metal sheets206,208, the signal wires210,212and the parasitic grounded metal sheets214,216are disposed on the substrate200. The annular grounded metal sheet202is substantially in a shape of an annularity with two openings that break an enclosed circle in half, and therefore the annular grounded metal sheet202is divided into two separate portions2020,2022. The rectangular grounded metal sheet204is disposed inside the annular grounded metal sheet and connects the portions2020and2022of the annular grounded metal sheet202; the portions2020,2022are respectively symmetric with respect to the rectangular grounded metal sheet204. The size and shape of the annular grounded metal sheet202and the rectangular grounded metal sheet204are respectively designed according to the size and shape of the waveguide14and the septum polarizer16, so that they match with each other. Moreover, the rectangular grounded metal sheet204extends from the annular grounded metal sheet202across the interior of the annularity in a way corresponding to a configuration of the septum polarizer16of the waveguide14. Therefore, by lining up the annular grounded metal sheet202with the waveguide14and by lining up the rectangular grounded metal sheet204with the septum polarizer16, the waveguide14, the septum polarizer16and the feeding apparatus20are put together to assemble the low noise block down-converter10as shown inFIG. 1. The parasitic grounded metal sheets214,216of the feeding apparatus20are extended outward from each side of the rectangular grounded metal sheet204oppositely, and the parasitic grounded metal sheets214and216are respectively symmetric with respect to the rectangular grounded metal sheet204. In addition, the feeding metal sheets206and208are respectively symmetric with respect to the rectangular grounded metal sheet204, and extend from the two openings of the annular grounded metal sheet202toward the interior of the annularity. The signal wires210and212are respectively connected to the feeding metal sheets206and208through the two openings of the annular grounded metal sheet202, and extend out (of the annularity) from the feeding metal sheets206and208. The signal wires210,212and the feeding metal sheets206,208do not come into contact with the annular grounded metal sheet202, and extending centerlines220,222of the feeding metal sheets206,208are respectively perpendicular to the rectangular grounded metal sheet204.

With the parasitic grounded metal sheets214,216and the feeding metal sheets206,208, the feeding apparatus20can simultaneously affect impedance and return loss at high frequencies and low frequencies.

Basically, the parasitic grounded metal sheets214,216of the feeding apparatus20are extended outward from each side of the rectangular grounded metal sheet204oppositely, and a extending centerline224of the parasitic grounded metal sheet214and a extending centerline226of the parasitic grounded metal sheet216are respectively extended to the center of the rectangular grounded metal sheet204; therefore, the parasitic grounded metal sheets214,216are vertically aligned to a center of the rectangular grounded metal sheets204. In addition, in this embodiment, the extending centerlines220,222,224,226overlap as shown inFIG. 2, because the feeding metal sheets206,208and the parasitic grounded metal sheets214,216may be all vertically aligned to the center of the rectangular grounded metal sheet204. However, in other embodiments, the extending centerlines220,222,224,226may be shifted to form different lines, and the parasitic grounded metal sheets214and216, for example, may be disposed close to one end of the rectangular grounded metal sheet204in such a situation. The parasitic grounded metal sheets214and216can ensure impedance matching at low frequencies, and have the impedance of the feeding apparatus20in operating frequency range to match better toward the low frequency end, thereby improving return loss at low frequencies.

On the other hand, because the feeding metal sheets206and208are symmetric, and because the widths of the feeding metal sheets206and208may vary respectively, the feeding metal sheet206(or, the feeding metal sheet208) may include several segments. In particular, the feeding metal sheet206comprises portions2060,2062,2064. The portion2060is electrically connected to the signal wire210; the portion2062and the portion2064extend toward the interior of the annularity of the annular grounded metal sheet202in sequence. The width of the portion2060may be substantially about the same size as that of the signal wire210, while the width of the portion2062is preferably less than that of the portion2060and that of the portion2064. Moreover, the structure of the feeding metal sheet208is identical and symmetrical to that of the feeding metal sheet206. The feeding metal sheet208comprises portions2080,2082,2084. The portion2080is electrically connected to the signal wire212; the portion2082and the portion2084extend toward the interior of the annularity of the annular grounded metal sheet202in sequence. The width of the portion2080may be substantially about the same size as that of the signal wire212, while the width of the portion2082is preferably less than that of the portion2080and that of the portion2084. Moreover, the width of the portion2060may be either equal to or distinct from that of the portion2064; the width of the portion2080may be either equal to or distinct from that of the portion2084. By modifying the widths of the feeding metal sheet206,208, the impedance can thus be changed, such that the impedance of the feeding apparatus20in operating frequency range tends to match better toward the high frequency end, thereby improving return loss at high frequencies.

In order to point out the improvement on return loss at low frequencies and high frequencies by means of the parasitic grounded metal sheets214,216and the feeding metal sheets206,208, respectively, please refer toFIG. 3AandFIG. 3B, which are schematic diagrams respectively illustrating a top view of a front surface of the feeding apparatus30and that of the feeding apparatus32according to embodiments of the present invention. Since the structure of the feeding apparatuses30,32is similar to that of the feeding apparatus20shown inFIG. 2, the similar parts are not detailed redundantly. Unlike the feeding apparatus20, the widths of the feeding metal sheets306,308of the feeding apparatus30respectively keep fixed, such that the effect of the parasitic grounded metal sheets214,216at low frequencies in Ku band (i.e., 10.7 GHz-11.7 GHz) is easy to tell. Moreover, the parasitic grounded metal sheets214,216of the feeding apparatus20are removed in the feeding apparatus32, and thus the effect of the feeding metal sheets206,208at high frequencies in Ku band (i.e., 11.7 GHz-12.75 GHz) is distinguishable.

Please refer toFIGS. 4A,4B,4C.FIG. 4Ais a schematic diagram illustrating how impedance of the feeding apparatuses20,30,32varies with frequencies.FIG. 4Bis a schematic diagram illustrating return loss of the feeding apparatuses20,30,32.FIG. 4Cis a schematic diagram illustrating the feeding apparatuses20,30,32in a Smith chart. InFIGS. 4A,4B,4C, the long dashed line indicates the feeding apparatus30, the short dashed line indicates the feeding apparatus32, and the solid line indicates the feeding apparatus20. As shown inFIG. 4A, with the parasitic grounded metal sheets214,216, the feeding apparatus30achieves an impedance match at low frequencies in Ku band (i.e., 10.7 GHz-11.7 GHz), meaning that the impedance is around 50 ohms (Ω). With the feeding metal sheets206,208, the feeding apparatus32achieves an impedance match at high frequencies in Ku band (i.e., 11.7 GHz-12.75 GHz), meaning that the impedance is around 50 ohms (Ω). As a result, by integrating the parasitic grounded metal sheets214,216into the feeding metal sheets206,208, the feeding apparatus20can achieve impedance matching from 10.7 GHz to 12.75 GHz, thereby boosting transmission efficiency.

As shown inFIG. 4B, the return loss of the feeding apparatus30at low frequencies (10.7 GHz-11.7 GHz) is lower, while the return loss of the feeding apparatus32at high frequencies (11.7 GHz-12.75 GHz) is lower. Accordingly, the feeding apparatus20, which combines with the parasitic grounded metal sheets214,216and the feeding metal sheets206,208, has lower return loss from 10.7 GHz to 12.75 GHz. Therefore, the return loss at high frequencies and low frequencies in Ku band can all meet requirements, which benefits signal transmission. In addition, as shown inFIG. 4C, the feeding apparatus30at high frequencies is distributed further from the center of the Smith chart, while the feeding apparatus32at low frequencies is distributed further from the center of the Smith chart. In comparison, the feeding apparatus20is distributed closer to the center of the Smith chart within Ku band (10.7 GHz-12.75 GHz), and reflection coefficient is therefore smaller.

As shown inFIGS. 4A to 4C, with the parasitic grounded metal sheets214,216and the feeding metal sheets206,208, the impedance of the feeding apparatus20matches the characteristic impedance of transmission lines, such that a good impedance match is simultaneously achieved at high frequencies and low frequencies, and reflection coefficient is reduced to increase transmission efficiency.

Please refer toFIGS. 5A and 5B.FIG. 5Ais a schematic diagram illustrating return loss of the feeding apparatuses100and20.FIG. 5Bis a schematic diagram illustrating the feeding apparatuses100and20in a Smith chart. InFIGS. 5A and 5B, the dashed line indicates the feeding apparatus100, and the solid line indicates the feeding apparatus20. As shown inFIG. 5A, the return loss of the feeding apparatus100within Ku band (10.7 GHz-12.75 GHz) is higher than that of the feeding apparatus20, such that transmission efficiency of the feeding apparatus100is worse than that of the feeding apparatus20of the present invention. Besides, as shown inFIG. 5B, the feeding apparatus20is distributed closer to the center of the Smith chart within Ku band (10.7 GHz-12.75 GHz) than the feeding apparatus100is; thus, the reflection coefficient of the feeding apparatus20is smaller than that of the feeding apparatus100, and the impedance of the feeding apparatus20matches the characteristic impedance of transmission lines more. In other words, comparing to the feeding apparatus100, the feeding apparatus20achieves impedance matching at high frequencies and low frequencies. As set forth above, by modifying the widths of the feeding metal sheets206,208, disposing the parasitic grounded metal sheets214,216, and properly adjusting the distance between the parasitic grounded metal sheet214and the feeding metal sheet206and between the parasitic grounded metal sheet216and the feeding metal sheet208, impedance matching at high frequencies and low frequencies can be effectively improved and return loss is also reduced.

Please note that the feeding apparatus20is an exemplary embodiment of the invention, and those skilled in the art can make alternations and modifications accordingly. For example, any kind or material of substrate on which layout can be drawn can be served as the substrate200. Preferably, the lengths of the feeding metal sheets206,208are substantially one quarter of the wavelength of received signals, but appropriate adjustments are also feasible. The back-end radio frequency processing unit coupled to the signal wires210,212may be a low noise amplifier, an intermediate frequency (IF) filter, an IF amplifier, other radio frequency circuits, or any combination thereof, but not limited thereto. Besides, the feedhorn12, the waveguide14and the septum polarizer16of the low noise block down-converter10here aim to illustrate the feeding apparatus20, and hence those skilled in the art might appropriately modify them according to different design considerations and system requirements. For example, the feedhorn12can be applied into different shapes of the opening, such as a square, circle, rectangle, rhombus and ellipse. Moreover, the feedhorn12may have corrugations inside to improve a radiation pattern of the feedhorn, such that the radiation pattern may be more symmetric and centralized to decrease a spillover loss of the feedhorn.

On the other hand, in the feeding apparatus20, extending centerlines220,222of the feeding metal sheets206,208are respectively perpendicular to the rectangular grounded metal sheet204; however, in other embodiments, there may be an included angle between the extending centerline of a feeding metal sheet and the rectangular grounded metal sheet204. Specifically, please refer toFIG. 6, which is a schematic diagram illustrating a top view of a front surface of a feeding apparatus60according to an embodiment of the present invention. The feeding apparatus60comprises a substrate600, an annular grounded metal sheet602, a rectangular grounded metal sheet604, feeding metal sheets606,608, signal wires610,612and parasitic grounded metal sheets614,616. Comparing the feeding apparatus20shown inFIG. 2and the feeding apparatus60shown inFIG. 6, although the structure of the feeding apparatus60is similar to that of the feeding apparatus20shown inFIG. 2, openings of the annular grounded metal sheet602locate differently from the openings of the annular grounded metal sheet202. The annular grounded metal sheet602is also in a shape of an annularity substantially with two openings that break an enclosed circle, and therefore the annular grounded metal sheet602is divided into two separate portions6020,6022of different sizes. The two openings are respectively at angles θ1and θ2with respect to the vertical. The feeding metal sheets606,608extend from the two openings of the annular grounded metal sheet602toward the interior of the annularity. That is to say, there is an included angle θ1between the extension of the rectangular grounded metal sheet604and the extending centerline of the feeding metal sheet606, and there is an included angle θ2between the extension of the rectangular grounded metal sheet604and the extending centerline of the feeding metal sheet608. Additionally, the feeding apparatus60may be operated in a way similar to the feeding apparatus20shown inFIG. 2; therefore, related details can be found from the aforementioned illustrations.

InFIG. 6, the included angles θ1, θ2may be in a range of 0° (degrees) to 90°, but not limited thereto. Since the effective length of the substrate600in the horizontal direction (i.e., the direction perpendicular to the rectangular grounded metal sheet604) depends on the orientation of the feeding metal sheets606,608, the effective length of the substrate600in the horizontal direction can effectively shrink by minimizing the included angles θ1, θ2. As a result, density of the back-end radio frequency processing unit increases, circuit layout area of the substrate200is saved, and fewer screws are required, thereby reducing product volume, product weight, and manufacturing cost.

Apart from location of the feeding metal sheets and location of the openings of the annular grounded metal sheet, branches may be added in each portion, and the shape of the feeding metal sheet may be modified. Please refer toFIGS. 7A to 7C, which are schematic diagrams respectively illustrating feeding metal sheets706,716,726according to embodiments of the present invention. The feeding metal sheets706,716,726can replace the feeding metal sheets206,208shown inFIG. 2(or the feeding metal sheets606,608shown inFIG. 6). As shown inFIG. 7A, the feeding metal sheet706comprises portions7060,7062,7064and branches7066,7068. When the feeding metal sheet706is utilized to replace the feeding metal sheets in previous embodiments, the portion7060is electrically connected to a signal wire (e.g., one of the signal wires210,212,610,612), the portion7062and the portion7064extend toward the interior of the annularity of the annular grounded metal sheet in sequence, and the branches7066and7068extends oppositely from two sides of the portion7062. As shown inFIG. 7B, the feeding metal sheet716comprises portions7160,7162,7164,7166. The portion7160is electrically connected to a signal wire, and the portions7162,7164and7166extend toward the interior of the annular of the annular grounded metal sheet in sequence. As shown inFIG. 7C, the feeding metal sheet726comprises portions7260,7262,7264,7266. The portion7260is electrically connected to a signal wire, the portions7262,7264,7266extend toward the interior of the annularity of the annular grounded metal sheet in sequence, and the portion7260,7262,7264,7266are in the shape of a curve.

InFIG. 7A, the branches7066,7068are disposed on the sides of the portion7062, but in other embodiments, branches may be designed on the sides of the portion7060or the portion7064, and the number of branches may be modified according different considerations. InFIG. 7B, the feeding metal sheet716is divided into four portions. The widths of the portion7162and the portion7166are greater than that of the portion7160and that of the portion7164, but not limited thereto. In other words, the widths of the portions can vary without following a specific rule and may not increase gradually. Moreover, the number of portions of the feeding metal sheet716is not limited to a specific value, but may be several portions. Consequently, with the number, relative width and shape of the portions properly adjusted and branches disposed, the impedance of the feeding apparatus can be changed as one would wish.

Apart from adjusting the structure of feeding metal sheets, location of parasitic grounded metal sheets with respect to the rectangular grounded metal sheet may be appropriately modified to meet the desired impedance. Please refer toFIG. 8, which is a schematic diagram illustrating a top view of a front surface of a feeding apparatus80according to an embodiment of the present invention. The feeding apparatus80comprises a substrate800, an annular grounded metal sheet802, a rectangular grounded metal sheet804, feeding metal sheets806,808, signal wires810,812and parasitic grounded metal sheets814,816. Comparing the feeding apparatus80to the feeding apparatus20shown inFIG. 2, although the structure of the feeding apparatus80is similar to that of the feeding apparatus20shown inFIG. 2, the parasitic grounded metal sheets814,816, with respect to the rectangular grounded metal sheet804, locate differently from the feeding apparatus20. As shown inFIG. 8, the parasitic grounded metal sheets814,816on opposite sides of the rectangular grounded metal sheet804may be disposed along the rectangular grounded metal sheet804but at different locations, and hence the cross shape formed by the rectangular grounded metal sheet804and the parasitic grounded metal sheets814,816varies. Additionally, the feeding apparatus80may be operated in a way similar to the feeding apparatus20shown inFIG. 2; therefore, related details can be found from the aforementioned illustrations.

The shape of the parasitic grounded metal sheets may be adjusted as the number of the portions increases. Please refer toFIGS. 9A to 9C.FIG. 9Ais a schematic diagram illustrating a locally enlarged view of a rectangular grounded metal sheet902and parasitic grounded metal sheets904,906according to an embodiment of the present invention.FIG. 9Bis a schematic diagram illustrating a locally enlarged view of a rectangular grounded metal sheet912and parasitic grounded metal sheets914,916according to an embodiment of the present invention.FIG. 9Cis a schematic diagram illustrating a locally enlarged view of a rectangular grounded metal sheet922and parasitic grounded metal sheets924,926according to an embodiment of the present invention. The rectangular grounded metal sheets902,912,922and the associated parasitic grounded metal sheets904,906,914,916,924,926can replace the rectangular grounded metal sheet204and the parasitic grounded metal sheets214,216shown inFIG. 2(or other embodiments). As shown inFIG. 9A, the parasitic grounded metal sheets904,906respectively extend from two opposite sides of the rectangular grounded metal sheet902, and the parasitic grounded metal sheets904,906are in the shape of a curve. As shown inFIG. 9B, the parasitic grounded metal sheets914,916respectively extend from two opposite sides of the rectangular grounded metal sheet912. The parasitic grounded metal sheet914comprises portions9140,9142of different widths; the parasitic grounded metal sheet916comprises portions9160,916of different widths. The variation of the widths may be further modified according to different system requirements. As shown inFIG. 9C, the parasitic grounded metal sheet924,926respectively extend from two opposite sides of the rectangular grounded metal sheet922. The parasitic grounded metal sheet924comprises portions9240,9242; the parasitic grounded metal sheet926comprises portions9260,9262. The variation of the widths of the portions9240,9242and the portions9260,9262may also be modified according to different system requirements. It is worth noting that the number of portions of the parasitic grounded metal sheets914,916,924,926shown inFIGS. 9B and 9Cis not limited to a specific value, but may be several portions. Moreover, the widths of the portions can vary without following a specific rule and may not increase gradually. Consequently, as the number, relative width and shape of the portions are properly adjusted, the impedance of the feeding apparatus can be changed as one would wish.

To sum up, by modifying widths of feeding metal sheets, disposing parasitic grounded metal sheets, and properly adjusting the distance between the parasitic grounded metal sheet and the feeding metal sheet, impedance of the feeding apparatus in operating frequency range match more toward both the low frequency end and the high frequency end, thereby improving return loss at high frequencies and low frequencies. In other words, a good impedance matching is achieved and return loss is reduced with the designed pattern of the feeding apparatus, and design freedom diverges while it is still easy to manufacture.