阅读说明：本技术 双工器 (Duplexer ) 是由 喻鸿飞 罗旭荣 于 2018-09-27 设计创作，主要内容包括：一种双工器,包括：第一滤波器,被配置为选择性地通过第一频率信号,第一滤波器包括第一连接器；第二滤波器,被配置为选择性地通过第二频率信号,第二滤波器包括第二连接器；以及第三滤波器,被配置为选择性地通过第一频率信号和第二频率信号,第三滤波器包括第三连接器,其中第三滤波器分开耦合到第一滤波器和第二滤波器,以及包括：至少第一腔和第二腔,其经由导电互连耦合,导电互连位于这样的壁中的孔内,该壁将第一腔与第二腔分开并且在第一腔和第二腔之间延伸。(A duplexer, comprising: a first filter configured to selectively pass a first frequency signal, the first filter comprising a first connector; a second filter configured to selectively pass a second frequency signal, the second filter including a second connector; and a third filter configured to selectively pass the first frequency signal and the second frequency signal, the third filter including a third connector, wherein the third filter is separately coupled to the first filter and the second filter, and including: at least a first cavity and a second cavity coupled via a conductive interconnect, the conductive interconnect being located within an aperture in a wall separating and extending between the first cavity and the second cavity.)

1. A duplexer, comprising:

a first filter configured to selectively pass a first frequency signal, the first filter comprising a first connector;

a second filter configured to selectively pass a second frequency signal, the second filter comprising a second connector; and

a third filter configured to selectively pass the first frequency signal and the second frequency signal, the third filter including a third connector,

wherein the third filter is coupled to the first filter and the second filter, respectively, an

The method comprises the following steps:

at least a first cavity and a second cavity, the first and second cavities coupled via a conductive interconnect located within an aperture in a wall separating and extending between the first and second cavities.

2. The duplexer of claim 1 wherein the conductive interconnect has rotational symmetry about an axis extending through the walls and holes.

3. The duplexer of claim 1 or 2 wherein the conductive interconnect has a width-wise portion extending through the aperture.

4. The duplexer of claim 3 wherein the conductive interconnect has a first heightwise portion extending through the first cavity to engage one end of the width-wise portion of the conductive interconnect and has a second heightwise portion extending through the second cavity to engage an opposite end of the width-wise portion.

5. The duplexer of claim 4 wherein the first and second heightwise portions are configured to have a height that depends on the first frequency.

6. The duplexer of claim 5 wherein the first frequency is inversely proportional to the height of the first heightwise portion.

7. The duplexer of claim 4, 5 or 6 wherein the first heightwise portion is configured to extend from a connection point at the base of the first cavity and the second heightwise portion is configured to extend from a connection point at the base of the second cavity.

8. The duplexer according to any one of claims 3 to 7, wherein the width-direction portion is configured to have a length depending on the first frequency and the second frequency.

9. The duplexer of any preceding claim wherein the conductive interconnects have a length that depends on the second frequency.

10. The duplexer of claim 9 wherein the second frequency is inversely proportional to a length of the conductive interconnect.

11. The duplexer of any preceding claim wherein the conductive interconnects are U-shaped.

12. The duplexer of any preceding claim wherein the conductive interconnects are metal.

13. The duplexer of any preceding claim, comprising a movable conductor electrically connected to the conductive interconnect, wherein the movable conductor is configured to be moved to tune a reactance of the conductive interconnect.

14. The duplexer of any preceding claim wherein the movable conductor is an adjustment screw.

15. The duplexer of any preceding claim wherein the first filter comprises a resonator and is resonant at the first frequency.

16. A frequency selective splitter/combiner comprising:

a first filter configured to selectively pass a first frequency signal, the first filter comprising a first connector;

a second filter configured to selectively pass a second frequency signal, the second filter comprising a second connector; and

a third filter configured to selectively pass the first frequency signal and the second frequency signal, the third filter including a third connector,

wherein the third filter is coupled to the first filter and the second filter, respectively, an

The method comprises the following steps:

at least one cavity; and

a conductive interconnect comprising a first end portion connected to a first portion of the cavity of the third filter, a second end portion connected to a second portion of the cavity of the third filter, and an intermediate portion that is free-standing and not connected to the cavity of the third filter.

17. An apparatus comprising the diplexer of any of claims 1-14 or the frequency selective splitter/combiner of claim 15.

18. The apparatus of claim 16, wherein the apparatus is a base station for mobile communications.

Technical Field

Embodiments of the present disclosure relate to duplexers and other frequency selective combiners.

Background

The diplexer is a frequency selective splitter/combiner. When operating as a combiner, two or more signals of different frequencies are combined for transmission via a common antenna. When operating as a splitter, two or more signals of different frequencies are split after reception at a common antenna. When a single antenna is used for simultaneous transmission and reception, the duplexer can also be used to isolate transmission in one or more frequencies from reception at one or more different frequencies. The duplexer enables multi-band and/or broadband communications.

Disclosure of Invention

According to various, but not necessarily all, embodiments there is provided a duplexer comprising: a first filter configured to selectively pass a first frequency signal, the first filter comprising a first connector; a second filter configured to selectively pass a second frequency signal, the second filter including a second connector; and a third filter configured to selectively pass the first frequency signal and the second frequency signal, the third filter including a third connector, wherein the third filter is coupled to the first filter and the second filter, respectively, and including: at least a first cavity and a second cavity coupled via a conductive interconnect located within an aperture in a wall separating and extending between the first cavity and the second cavity.

In some, but not necessarily all examples, the conductive interconnects have rotational symmetry about an axis extending through the wall and the aperture.

In some, but not necessarily all, examples, the conductive interconnects have a width-wise portion that extends through the vias.

In some, but not necessarily all, examples, the conductive interconnects have a first heightwise portion that extends through the first cavity to engage one end of the width-wise portion of the conductive interconnect, and have a second heightwise portion that extends through the second cavity to engage an opposite end of the width-wise portion.

In some, but not necessarily all, examples, the first heightwise portion and the second heightwise portion are configured to have a height that depends on the first frequency.

In some, but not necessarily all, examples, the first frequency is inversely proportional to the height of the first elevation direction portion.

In some, but not necessarily all, examples, the first heightwise portion is configured to extend from a connection point at a base of the first cavity, and the second heightwise portion is configured to extend from a connection point at a base of the second cavity.

In some, but not necessarily all, examples, the width-directional portion is configured to have a length that depends on the first frequency and the second frequency.

In some, but not necessarily all, examples, the conductive interconnects have a length that depends on the second frequency.

In some, but not necessarily all examples, the second frequency is inversely proportional to the length of the conductive interconnect.

In some, but not necessarily all examples, the conductive interconnects are U-shaped.

In some, but not necessarily all examples, the conductive interconnects are metal.

In some, but not necessarily all examples, the duplexer comprises a movable conductor electrically connected to the conductive interconnect, wherein the movable conductor is configured to be moved to tune a reactance of the conductive interconnect.

In some, but not necessarily all examples, the movable conductor is an adjustment screw.

In some, but not necessarily all examples, the first filter includes a resonator and resonates at a first frequency.

According to various, but not necessarily all, embodiments there is provided a frequency selective splitter/combiner comprising: a first filter configured to selectively pass a first frequency signal, the first filter comprising a first connector; a second filter configured to selectively pass a second frequency signal, the second filter including a second connector; and a third filter configured to selectively pass the first frequency signal and the second frequency signal, the third filter including a third connector, wherein the third filter is coupled to the first filter and the second filter, respectively, and including: at least one cavity; and a conductive interconnect comprising a first end portion connected to the cavity of the third filter, a second end portion connected to the second portion of the cavity of the third filter, and an intermediate portion that is free-standing and not connected to the cavity of the third filter.

According to various, but not necessarily all, embodiments there is provided an apparatus comprising a duplexer. According to various, but not necessarily all, embodiments, the apparatus is a base station for mobile communications.

According to various, but not necessarily all, embodiments there is provided an apparatus comprising: a first filter configured to selectively pass a first frequency signal, the first filter comprising a first connector; a second filter configured to selectively pass a second frequency signal, the second filter including a second connector; and a third filter configured to selectively pass the first frequency signal and the second frequency signal, the third filter including a third connector, wherein the third filter is coupled to the first filter and the second filter, respectively, and including: at least a first cavity and a second cavity coupled via a conductive interconnect located within an aperture in a wall separating and extending between the first cavity and the second cavity.

According to various, but not necessarily all, embodiments there is provided a base station for mobile communications, comprising: a first filter configured to selectively pass a first frequency signal, the first filter comprising a first connector; a second filter configured to selectively pass a second frequency signal, the second filter including a second connector; and a third filter configured to selectively pass the first frequency signal and the second frequency signal, the third filter including a third connector, wherein the third filter is coupled to the first filter and the second filter, respectively, and including: at least a first cavity and a second cavity coupled via a conductive interconnect located within an aperture in a wall separating and extending between the first cavity and the second cavity.

According to various, but not necessarily all, embodiments, there are provided examples as claimed in the appended claims.

Drawings

Some example embodiments will now be described with reference to the accompanying drawings, in which:

FIG. 1 illustrates an example embodiment of the subject matter described herein;

FIG. 2 illustrates another example embodiment of the subject matter described herein;

3A, 3B, 3C illustrate another example embodiment of the subject matter described herein;

FIG. 4 illustrates another example embodiment of the subject matter described herein;

fig. 5 illustrates another example embodiment of the subject matter described herein.

Detailed Description

Fig. 1 shows an example of a duplexer 100, including:

a first filter 110 configured to selectively pass a first frequency signal 111, the first filter 110 including a first connector 102;

a second filter 120 configured to selectively pass a second frequency signal 121, the second filter 120 including a second connector 104; and

a third filter 130 configured to selectively pass the first frequency signal 111 and the second frequency signal 121, the third filter 130 including a third connector 106.

The diplexer is a frequency selective splitter/combiner.

The first frequency signal 111 is a signal having an operating bandwidth centered at the first frequency F1. The first filter 110 includes resonators and resonates at the first frequency F1 but does not resonate at the second frequency F2.

The second frequency signal 121 is a signal having an operating bandwidth centered at the second frequency F2. The second filter includes resonators and resonates at the second frequency F2 but not at the first frequency F1.

The third filter 130 is coupled to the first filter 110 and the second filter 120, respectively.

Fig. 2 shows an example of the third filter 130 in more detail.

The conductive interconnect 150 includes a first end 163a, a second end 163b, and an intermediate portion 136, the first end 163a being connected to the first portion 133a of the wall of the cavity 132 of the third filter 130, the second end 163b being connected to the second portion 133b of the wall of the cavity 134 of the third filter 130. In some examples, the middle portion 136 is freestanding and self-supporting. In some examples, the conductive interconnect 150 is not connected to any wall of the third filter 130.

In this example, the third filter 130 includes: at least a first chamber 132 and a second chamber 134.

The first cavity 132 and the second cavity 134 are coupled via a conductive interconnect 150. The conductive interconnect 150 is located within the aperture 140 in the wall 142, the wall 142 separating the first cavity 132 from the second cavity 134 and extending between the first cavity 132 and the second cavity 134.

In this example, the first and second cavities 132, 134 are capacitively coupled via an aperture 140 in a wall 142 separating the first cavity 132 from the second cavity 134, and are inductively coupled via a conductive interconnect 150 located within the aperture 140 and extending between the first and second cavities 132, 134. The aperture 140 is an opening through the wall 142 that provides an interconnected volume of dielectric (e.g., air) between the volume of dielectric (e.g., air) in the first cavity 132 and the volume of dielectric (e.g., air) in the second cavity 134. The size (e.g., cross-sectional area and/or volume), shape, and location of the aperture 140 may be varied, for example, to adjust the operating characteristics of the duplexer 100. In some examples, the aperture 140 is a through-hole located entirely within the wall 142, while in other examples, the aperture 140 is a cutout located at one or more edges of the wall 142.

In some examples, the conductive interconnects 150 are located within the apertures 140 and pass through the apertures without contacting portions of the walls 142 that define the apertures 142.

In this example, but not necessarily all examples, the conductive interconnect 150 has rotational symmetry about an axis 152, the axis 152 extending through the wall 142 and the aperture 140 in the first direction.

The intermediate portion 136 of the conductive interconnect 150 is a widthwise portion 160 that extends through the via 140. The conductive interconnect 150 has a first heightwise portion 162 and has a second heightwise portion 164, the first heightwise portion 162 extending through the first cavity 132 to engage one end 161A of the width-wise portion 160 of the conductive interconnect 150, and the second heightwise portion 164 extending through the second cavity 134 to engage an opposite end 161B of the width-wise portion 160.

In this example, the conductive interconnect 150 is U-shaped. The U-shape is shown in more detail in fig. 3A, 3B, 3C. These figures show the outer surface 154 of the conductive interconnect 150 and the wall 138 of the third filter 130. Fig. 3A is a cross-section in the x-z plane of fig. 2. Fig. 3B is a cross-section in the y-z plane of fig. 2. Fig. 3C is a cross-section of the x-y plane of fig. 2. The first direction (z) is parallel to the z-axis. It is defined by a unit vector z. The second direction (x) is parallel to the x-axis. It is defined by a unit vector x. The third direction (y) is parallel to the y-axis. It is defined by a unit vector y. Unit vectors are mutually orthogonal: and z is x ^ y.

In this example, the conductive interconnects 150 are metal.

In this example, the first heightwise portion 162 extends upwardly in the first direction (z) within the cavity 132, and the second heightwise portion 164 extends upwardly in the first direction (z) within the cavity 134. The width-direction portion 160 extends in a second direction (x) orthogonal to the first direction (z).

Referring back to fig. 2, the first heightwise portion 162 is configured to extend from a connection point 163A at the base 133A of the first cavity 132, while the second heightwise portion 164 is configured to extend from a connection point 163B at the base 133B of the second cavity 134. The base 133A is a floor portion of the wall 138 of the first chamber 132. The base 133B is a floor portion of the wall 138 of the second chamber 134. In at least some examples, the connection points 163A, 163B comprise metal-to-metal connections formed, for example, by welding.

The conductive interconnect 150 has two primary resonant modes at the same time.

(i) A vertical 1/4 lambda resonator with a physical length H has an electrical length H'. Thus, the first resonant frequency F1 is at 1/4 λ₁H', where λ₁Is the resonant wavelength corresponding to the resonant frequency F1.

(ii) The 1/2 λ resonator with a physical length X ═ 2H + W has an electrical length X'. Thus, the second resonant frequency F2 is at 1/2 λ₂X' where λ₂Is the resonant wavelength corresponding to the resonant frequency F2.

The connection of the two ends 163A, 163B of the conductive interconnect 150 forces a half-wavelength resonant mode.

Let k_HH' ═ H, where k is_HIs a constant and is a velocity factor.

&k_xX' ═ X, where k_XIs a constant and is a velocity factor.

Thus λ₁＝4H’＝(4H/k_H)＝(1/k_H)(4H)

And λ₂＝2X’＝(2X/k_x)＝(1/k_x)(4H+2W)

If we assume k_H＝k_x＝k.

To obtain lambda₂＝1.1λ₁Then 1.1^＊4H ═ (4H +2W), i.e., W ═ 0.2H.

To obtain lambda₂＝1.2λ₁Then 1.2^＊4H ═ (4H +2W), i.e., W ═ 0.4H.

To obtain lambda₂＝1.3λ₁Then 1.3^＊4H ═ (4H +2W), i.e., W ═ 0.6H.

Simulations may be used to determine the dimensions of the conductive interconnect 150 for the desired first frequency F1 and the desired second lower frequency F2.

Thus, the two operating bandwidths associated with the first frequency F1 and the second frequency F2 may cover a significant portion of the radio frequency spectrum used for telecommunications, such as 890MHz to 2700MHz for 3 GPP.

1/4 lambda first harmonic of resonator (lambda)₁First harmonic (lambda) of/4) and 1/2 lambda resonators₂Combination ratio of/2) 1/4 λ first harmonic of resonator (λ)₁/4) and 1/4Second harmonic of lambda resonator (3 lambda)₁The combination of/4) provides better coverage.

If each resonator of the conductive interconnect 150 is modeled as a simple LC circuit with a difference in capacitance C and inductance L, then the resonant frequency is AND (LC)^-1/2Linearly proportional, and thus the corresponding resonance wavelength and (LC)^1/2Is in direct proportion. To a first approximation, L and C are both linearly proportional to the conductor length, and thus the resonance wavelength depends on the physical length of the resonator (W or X), which is proportional to the physical length of the resonator (W or X). This linear relationship is represented by the velocity factor k. It will be appreciated, however, that the electrical length of the conductor/resonator may be tuned by changing its reactance (changing L and/or C). This can be achieved, for example, by connecting discrete components such as capacitors or inductors or by changing the way the conductor/resonator interacts with its own magnetic field (L) or the way the conductor/resonator interacts with a nearby electric field (C). This may be accomplished, for example, by varying the shape and size of the conductive interconnect 150 and its relationship to the nearby conductors 138, 142, such as distance or dielectric constant.

Accordingly, the first and second heightwise portions 162 and 164 are configured to have a height H that depends on the first frequency F1. In some, but not necessarily all examples, first frequency F1 is inversely proportional to height H of first heightwise portion 162, e.g., λ₁Is proportional to H.

The conductive interconnect 150 has a length (X ═ 2H + W) that depends on the second frequency F2. In some, but not necessarily all examples, the second frequency F2 is inversely proportional to the length X of the conductive interconnect 150, e.g., λ₂Is proportional to X.

The width-direction portion 160 is configured to have a length W that depends on the first frequency F1 and the second frequency F2, e.g., W ═ k · (λ)₂-λ₁)/2。

Fig. 4 shows an example of the third filter 130 shown in fig. 2. The third filter 130 includes a movable conductor 170 electrically connected to the conductive interconnect 150. The movable conductor 170 is configured to be moved to tune the reactance of the conductive interconnect 150. In this example, the movable conductor 170 is an adjustment screw. In some, but not necessarily all examples, some or all of the movable conductors 170 are configured for manual movement.

Referring back to fig. 1, in at least one example, the external dimensions of the duplexer 100 fit within a cuboid having dimensions 20 x 74 x 76(mm), with the first frequency F1 being 2.03GHz and the second, lower frequency being 1.04 (GHz). Therefore, it has a compact size as compared with the present duplexer.

Fig. 5 shows an example of a base station 200 or other telecommunications node comprising a duplexer 100 connected to an antenna 202. The base station may be a cellular base station.

The radio frequency circuitry and antenna 202 comprising the duplexer 100 may be configured to operate in multiple operational resonant frequency bands. For example, the operating frequency band may include, but is not limited to, Long Term Evolution (LTE) (usa) (734 to 746MHz and 869 to 894 MHz); long Term Evolution (LTE) (elsewhere in the world) (791 to 821MHz and 925 to 960 MHz); amplitude Modulation (AM) radio (0.535-1.705 MHz); frequency Modulation (FM) radio (76-108 MHz); bluetooth (2400-2483.5 MHz); wireless Local Area Networks (WLANs) (2400-2483.5 MHz); HiperLAN (5150 and 5850 MHz); global Positioning System (GPS) (1570.42-1580.42 MHz); U.S. Global System for Mobile communications (US-GSM)850(824-894MHz) and 1900(1850-1990 MHz); european Global System for Mobile communications (EGSM)900(880-960MHz) and 1800(1710-1880 MHz); european wideband code division multiple Access (EU-WCDMA)900(880-960 MHz); personal communication network (PCN/DCS)1800(1710 and 1880 MHz); wideband code division multiple access (US-WCDMA)1700 (transmission: 1710 to 1755MHz, reception: 2110 to 2155MHz) and 1900 (1850-; wideband Code Division Multiple Access (WCDMA)2100 (transmission: 1920-1980MHz, reception: 2110-2180 MHz); personal Communications Services (PCS)1900 (1850-; time division synchronous code division multiple access (TD-SCDMA) (1900MHz to 1920MHz, 2010MHz to 2025 MHz); ultra-wideband (UWB) low frequency (3100-; UWB high frequency (6000-; digital video broadcast-handheld (DVB-H) (470 and 702 MHz); DVB-H USA (1670-; digital radio single frequency (DRM) (0.15-30 MHz); worldwide interoperability for microwave access (WiMax) (2300 + 2400MHz, 2305 + 2360MHz, 2496 + 2690MHz, 3300 + 3400MHz, 3400 + 3800MHz, 5250 + 5875 MHz); digital Audio Broadcasting (DAB) (174.928-239.2MHz, 1452.96-1490.62 MHz); radio frequency identification low frequency (RFID LF) (0.125-0.134 MHz); radio frequency identification high frequency (RFID HF) (13.56-13.56 MHz); the radio frequency identification (RFID UHF) (433MHz, 865-956MHz, 2450 MHz).

These include low frequency cells (824-. The lower cellular band (824-960MHz) comprises US-GSM 850(824-894 MHz); EGSM 900(880-960 MHz); EU-WCDMA 900(880-960 MHz). The higher cellular band (1710-; the US-WCDMA1900 (1850) -1990MHz frequency band; WCDMA21000 frequency band (emission: 1920-1980MHz reception: 2110-2180 MHz); PCS1900 (1850-.

The resonant mode of operation (operating bandwidth) is the frequency range over which the antenna can operate efficiently. The frequency band in which the antenna can operate efficiently is the frequency range in which the return loss of the antenna is less than the operating threshold.

A diplexer, as used herein, refers to a device that frequency multiplexes multiple (N) ports onto one port, where N ≧ 2, i.e., it operates at least as a diplexer. A two-input port duplexer is used in this document to refer to an N-2 duplexer. The triplexer is an N-3 duplexer. The four-way multiplexer is an N-4 duplexer. The additional resonant frequencies can be generated by higher harmonics of the conductive interconnects 150 or by introducing one or more additional conductive interconnects 150, as described above, which conductive interconnects 150 have different electrical lengths and different 1/4 λ resonances and 1/2 λ resonances.

Where a structural feature has been described, it may be replaced by means for performing one or more functions of the structural feature, whether or not the function or functions are explicitly described or implicitly described.

As used herein, "module" refers to a unit or device that does not include certain parts/components that are to be added by the end manufacturer or user. The duplexer 100 is a module.

The above examples find application as enabling components for: an automotive system; a telecommunications system; electronic systems including consumer electronics; a distributed computing system; a media system for generating or presenting media content (including audio, visual and audiovisual content as well as mixed, mediated, virtual and/or augmented reality); a personal system including a personal health system or a personal fitness system; a navigation system; user interfaces, also known as human-machine interfaces; networks including cellular, non-cellular, and optical networks; an ad hoc network; the internet; the Internet of things; a virtualized network; and related software and services.

The term "comprising" as used in this document has an inclusive rather than exclusive meaning. In other words, any reference to X including Y indicates that X may include only one Y or may include more than one Y. If the intent is to use "including" in the exclusive sense, then the context will be apparent by reference to "including only one" or using "consisting of ….

In this specification, various examples are referenced. The description of features or functions with respect to the examples indicates that those features or functions are present in the examples. The use of the terms "example" or "such as" or "can" or "may" in this text means that, whether or not explicitly stated, at least such features or functions are present in the described examples, whether or not described as examples, and that they may, but need not, be present in some or all of the other examples. Thus, "examples," e.g., "can" or "may" refer to particular instances in a class of examples. The properties of an instance may be the properties of the instance only, or may be the properties of a class, or may be the properties of a subclass of a class (including some but not all examples in a class). Thus, features described with reference to one example are implicitly disclosed rather than with reference to another example, which may be used as part of a working combination where possible, but which need not necessarily be.

Although embodiments have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the claims.

Features described in the foregoing description may be used in different combinations than those explicitly described above.

Although functions have been described with reference to certain features, the functions may be performed by other features, whether described or not.

Although features have been described with reference to certain embodiments, such features may also be present in other embodiments whether described or not.

The terms "a" and "an" or "the" as used in this document have an inclusive rather than an exclusive meaning. That is, any reference to X including a/the Y indicates that X may include only one Y or may include more than one Y unless the context clearly indicates the contrary. If the intention is to use "a" or "the" in an exclusive sense, it will be clear from the context. In some cases, "at least one" or "one or more" may be used to emphasize an inclusive meaning, but the absence of such terms should not be taken to imply an exclusive meaning.

The presence of a feature (or combination of features) in a claim is a reference to that feature (or combination of features) by itself, or to that feature (or equivalent feature) which achieves substantially the same technical effect. For example, equivalent features include features that are variants and achieve substantially the same result in substantially the same way. For example, equivalent features include features that perform substantially the same function in substantially the same way to achieve substantially the same result.

In this specification, reference has been made to various examples using adjectives or adjective phrases to describe features of the examples. Such description of example-related characteristics indicates that the characteristics exist entirely as described in some examples, and substantially as described in other examples.

Whilst endeavoring in the foregoing specification to draw attention to those features believed to be of importance it should be understood that the applicant may seek protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.