Patent Grant
10389035
Antenna arrays including waveguide antenna elements can provide desirable performance for communication over long distances. Passive antenna arrays with waveguide feed networks are one of the most suited technologies for antenna arrays because of the low level of losses they exhibit. As the number of antenna elements increases, the waveguide feed networks become increasingly complex and space consuming. This can be problematic in many environments (e.g., avionics) where space and/or weight are at a premium. In some cases, inter-element distance between the antenna elements may be constrained by the feed network size, which may degrade antenna performance.
A common problem with this type of architecture is grating lobes in the radiation pattern of the array, which happens if the inter-element distance is too large. Indeed, the fact that waveguides occupy more lateral space than other types of transmission medium (e.g., microstrip, etc.) can make it difficult to reduce the inter-element distance sufficiently to avoid grating lobes. This limitation can be even more severe with dual-polarized arrays, where the feed network system handles two channels, for the two orthogonal basis polarizations. Current architectures of dual-polarized antenna arrays using waveguide antenna elements use a larger than desired inter-element distance or sharing of a common excitation port among multiple antenna elements. These solutions can have drawbacks including increased grating lobes or reduced antenna efficiency.
A waveguide architecture for a dual-polarized antenna including multiple antenna elements. Aspects are directed to architectures where each antenna element includes a polarizer having an individual waveguide with dual-polarization signal propagation and divided waveguides associated with each basis polarization. In some aspects, the waveguide architecture includes unit cells having corporate waveguide networks associated with each basis polarization connecting each divided waveguide of the polarizers of each antenna element in the unit cell with a respective common waveguide. The inter-element distance for antenna elements within each unit cell may be small relative to the desired operational frequency range (e.g., to provide grating lobe free operation at the highest operating frequency, etc.) and unit cells may be positioned adjacent to each other in a waveguide device assembly for a dual-polarized antenna array without increased inter-element distance between antenna elements of adjacent unit cells. Antenna waveguide ports may be connected to unit cell common waveguides using elevation and azimuth waveguide networks of the corporate type.
A dual-polarized antenna is described. The dual-polarized antenna may include multiple unit cells, where each unit cell includes a first common waveguide associated with a first polarization, a second common waveguide associated with a second polarization, a two-by-two array of antenna elements, each antenna element including a polarizer coupled between an individual waveguide and first and second divided waveguides associated with the first and second polarizations, respectively, and where a cross-section of the individual waveguides of the two-by-two array defines a unit cell boundary for each unit cell, a first waveguide network comprising at least one waveguide combiner/divider and connecting each of the first divided waveguides of the plurality of antenna elements with the first common waveguide via a continuous waveguide signal path, and a second waveguide network including at least one waveguide combiner/divider and connecting each of the second divided waveguides of the plurality of antenna elements with the second common waveguide via a continuous waveguide signal path. The first waveguide network and the second waveguide network may each be entirely within a projection of the unit cell boundary along a direction that is normal to the cross-section that defines unit cell boundary.
Further scope of the applicability of the described methods and apparatuses will become apparent from the following detailed description, claims, and drawings. The detailed description and specific examples are given by way of illustration only, since various changes and modifications within the scope of the description will become apparent to those skilled in the art.
A further understanding of the nature and advantages of embodiments of the present disclosure may be realized by reference to the following drawings. In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
The described features generally relate to a dual polarized antenna (referred to herein as an “antenna array” or simply an “antenna”). The described features include a scalable waveguide architecture for a dual-polarized antenna using unit cells having multiple antenna elements, where each antenna element includes a polarizer (e.g., septum polarizer) having divided waveguide ports associated with each basis polarization. The unit cells may have corporate waveguide networks associated with each basis polarization connecting the divided waveguides of each antenna element to common waveguides of the unit cell associated with each basis polarization. The waveguide networks may include ridged waveguide components and/or non-ridged waveguide components. The inter-element distance between antenna elements within each unit cell may be selected to provide grating lobe free operation at the highest operating frequency and unit cells may be positioned adjacent to each other without increasing inter-element distance between antenna elements of adjacent unit cells. Thus, the inter-element distance may be small relative to the operating frequency range and consistent across a waveguide assembly of unit cells, minimizing grating lobes for the dual-polarized antenna.
This description provides examples, and is not intended to limit the scope, applicability or configuration of embodiments of the principles described herein. Rather, the ensuing description will provide those skilled in the art with an enabling description for implementing embodiments of the principles described herein. Various changes may be made in the function and arrangement of elements.
Thus, various embodiments may omit, substitute, or add various procedures or components as appropriate. For instance, it should be appreciated that the methods may be performed in an order different than that described, and that various steps may be added, omitted or combined. Also, aspects and elements described with respect to certain embodiments may be combined in various other embodiments. It should also be appreciated that the following systems, methods, devices, and software may individually or collectively be components of a larger system, wherein other procedures may take precedence over or otherwise modify their application.
The gateway 115 communicates with one or more networks 120. In operation, the satellite communication system 100 provides for two-way communications between the aircraft 130 and the network 120 through the satellite 105 and the gateway 115.
The satellite 105 may be any suitable type of communication satellite. In some examples, the satellite 105 may be in a geosynchronous orbit. In other examples, any appropriate orbit (e.g., low earth orbit (LEO), medium earth orbit (MEO), etc.) for satellite 105 may be used. The satellite 105 may be a multi-beam satellite configured to provide service for multiple service beam coverage areas in a predefined geographical service area. In some examples, the satellite communication system 100 includes multiple satellites 105.
The gateway antenna system 110 may be two-way capable and designed with adequate transmit power and receive sensitivity to communicate reliably with the satellite system 105. The satellite system 105 may communicate with the gateway antenna system 110 by sending and receiving signals through one or more beams 160. The gateway 115 sends and receives signals to and from the satellite system 105 using the gateway antenna system 110. The gateway 115 is connected to the one or more networks 120. The networks 120 may include a local area network (LAN), metropolitan area network (MAN), wide area network (WAN), or any other suitable public or private network and may be connected to other communications networks such as the Internet, telephony networks (e.g., Public Switched Telephone Network (PSTN), etc.), and the like.
The aircraft 130 includes an on-board communication system including a dual-polarized antenna 140. The aircraft 130 may use the dual-polarized antenna 140 to communicate with the satellite 105 over one or more beams 150. The dual-polarized antenna 140 may be mounted on the outside of the fuselage of aircraft 130 under a radome 135. The dual-polarized antenna 140 may be mounted to a positioner 145 used to point the dual-polarized antenna 140 at the satellite 105 (e.g., actively tracking) during operation. The dual-polarized antenna 140 may be used for receiving communication signals from the satellite 105, transmitting communication signals to the satellite 105, or bi-directional communication with the satellite 105 (transmitting and receiving communication signals). The dual-polarized antenna 140 may operate in the International Telecommunications Union (ITU) Ku, K, or Ka-bands, for example from approximately 17 to 31 Giga-Hertz (GHz). Alternatively, the antenna 140 may operate in other frequency bands such as C-band, X-band, S-band, L-band, and the like.
The on-board communication system of the aircraft 130 may provide communication services for communication devices of the aircraft 130 via a modem (not shown). Communication devices may connect to and access the networks 120 through the modem. For example, mobile devices may communicate with one or more networks 120 via network connections to modem, which may be wired or wireless. A wireless connection may be, for example, of a wireless local area network (WLAN) technology such as IEEE 802.11 (Wi-Fi), or other wireless communication technology.
The size of the dual-polarized antenna 140 may directly impact the size of the radome 135, for which a low profile may be desired. In other examples, other types of housings are used with the dual-polarized antenna 140. Additionally, the dual-polarized antenna 140 may be used in other applications besides onboard the aircraft 130, such as onboard boats, vehicles, or on ground-based stationary systems.
For antennas using multiple waveguide elements for radiating and receiving energy, the operational frequency range of the antenna may be determined by the dimensions of each of the waveguide elements and the inter-element distance (distance from center-to-center of adjacent waveguide elements). For example, a lower cutoff frequency for each antenna element may be dependent on the cross-sectional dimensions of the waveguide element serving as a port between the antenna element and the transmission medium. Generally, as the operational frequency approaches the lower cutoff frequency, the efficiency of signal propagation decreases. To provide grating lobe free operation, the inter-element distance should be small relative to the desired operational frequency range (e.g., an inter-element distance less than or equal to one wavelength at the highest operating frequency for a non-electrically steered antenna, etc.). To provide efficient operation across the operational frequency range, it may be desirable to feed a large number of antenna elements using continuous waveguide combiner/divider networks (e.g., with no changes in propagation medium). These waveguide combiner/divider networks may be complex and may include several stages that extend back behind the aperture plane of the antenna, increasing the depth of the antenna dramatically as the array size increases. In some applications, the depth of the antenna may be constrained by a physical enclosure (e.g., radome 135, etc.), and thus the overall size of the antenna elements and waveguide combiner/divider networks may limit the number of antenna elements that can be used, thus limiting performance of the antenna.
Each antenna element 225 may include an individual waveguide 220 for emitting and receiving waves and a polarizer. The polarizer can convert a signal between dual polarization states in the individual waveguide 220 and two signal components in respective divided waveguides 210 and 215 that correspond to orthogonal basis polarizations. This facilitates simultaneous dual-polarized operation. For example, from a receive perspective, the polarizer can be thought of as receiving a signal in the individual waveguide 220, taking the energy corresponding to a first basis polarization of the signal and substantially transferring it into a first divided waveguide 210, and taking the energy corresponding to a second basis polarization of the signal and substantially transferring it into a second divided waveguide 215. From a transmit perspective, excitations of the first divided waveguide 210 results in energy of the first basis polarization being emitted from the individual waveguide 220 while the energy from excitations of the second divided waveguide 215 results in energy of the second basis polarization being emitted from the individual waveguide 220.
The polarizer may include an element that is asymmetric to one or more modes of signal propagation. For example, the polarizer may include a septum 250 configured to be symmetric to the TE10 mode (e.g., component signals with their E-field along Y-axis 280 in individual waveguide 220) while being asymmetric to the TE01 mode (e.g., component signals with their E-field along X-axis 270 in individual waveguide 220). The septum 250 may facilitate rotation of the TE01 mode without changing signal amplitude, which may result in addition and cancellation of the TE01 mode with the TE10 mode on opposite sides of the septum 250. From the dividing perspective (e.g., a received signal propagating in the individual waveguide 220 in the negative Z-direction), the TE01 mode may additively combine with the TE10 mode for a signal having right hand circular polarization (RHCP) on the side of the septum 250 coupled with the first divided waveguide 210, while cancelling on the side of the septum 250 coupled with the second divided waveguide 215. Conversely, for a signal having left hand circular polarization (LHCP), the TE01 mode and TE10 mode may additively combine on the side of the septum 250 coupled with the second divided waveguide 215 and cancel each other on the side of the septum 250 coupled with the first divided waveguide 210. Thus, the first and second divided waveguides 210, 215 may be excited by orthogonal basis polarizations of polarized waves incident on the individual waveguide 220, and may be isolated from each other. In a transmission mode, excitations of the first and second divided waveguides 210, 215 (e.g., TE10 mode signals) may result in corresponding RHCP and LHCP waves, respectively, emitted from the individual waveguide 220.
The polarizer may be used to transmit or receive waves having a combined polarization (e.g., linearly polarized signals having a desired polarization tilt angle) at the individual waveguide 220 by changing the relative phase of component signals transmitted or received via the first and second divided waveguides 210, 215. For example, two equal-amplitude components of a signal may be suitably phase shifted and sent separately to the first divided waveguide 210 and the second divided waveguide 215, where they are converted to an RHCP wave and an LHCP wave at the respective phases by the septum 250. When emitted from the individual waveguide 220, the LHCP and RHCP waves combine to produce a linearly polarized wave having an orientation at a tilt angle related to the phase shift introduced into the two components of the transmitted signal. The transmitted wave is therefore linearly polarized and can be aligned with a polarization axis of a communication system. Similarly, a wave having a combined polarization (e.g., linear polarization) incident on individual waveguide 220 may be split into component signals of the basis polarizations at the divided waveguides 210, 215 and recovered by suitable phase shifting of the component signals in a receiver. Although the polarizer is illustrated as a stepped septum polarizer, other types of polarizers may be used including sloped septum polarizers or other polarizers.
The antenna element 225 may operate over one or more frequency bands, and may operate in a uni-directional (transmit or receive) mode or in a bi-directional (transmit and receive) mode. For example, the antenna element may be used to transmit and/or receive a dual-band signal is characterized by operation using two signal carrier frequencies. In some instances, the antenna element 225 may operate in a transmission mode for a first polarization (e.g., LHCP, first linear polarization) while operating in a reception mode for a second, orthogonal polarization in the same or a different frequency band.
The multiple antenna elements 225 include waveguide networks (discussed in more detail below) that can provide for a small inter-element distance relative to the operating frequency range which can reduce or eliminate grating lobes. Furthermore, the described waveguide networks improve efficiency by coupling common feed ports to the divided waveguides 210, 215 of multiple antenna elements 225 using continuous waveguide signal paths without changes in transmission medium. The described waveguide networks may include ridged waveguide components and/or non-ridged waveguide components. In addition, the described waveguide networks can maintain equal path lengths between waveguide networks feeding each divided waveguide 210, 215 for the antenna elements 225. In aspects, the waveguide feed networks include initial combiner/divider stages connected to the antenna elements 225 that route waveguide signal paths from divided waveguides 210, 215 of a set of antenna elements 225 to a common port within a projection of a cross-sectional boundary of the set of antenna elements 225 while maintaining a desired (e.g., small) inter-element distance between antenna elements 225. These techniques provide a scalable architecture for connecting divided waveguides of multiple antenna elements using continuous waveguide signal paths.
In embodiments of the dual-polarized antennas 140 of
The positioner 145-a may include an elevation motor and gearbox, an elevation alignment sensor, an azimuth motor and gearbox, and an azimuth alignment sensor. These components may be used to point the dual-polarized antenna 140-a at the satellite (e.g., satellite 105 in
The antenna subsystem 300 includes a waveguide device 305, which may have multiple waveguide networks associated with first and second basis polarizations coupled with multiple polarizers. In the antenna subsystem 300 as illustrated in
The waveguide device 305 includes an elevation combiner/divider stage 375, which may include an elevation power combiner/divider network 355 associated with each polarization. For example, elevation combiner/divider stage 375 may include a first elevation power combiner/divider network 355-a associated with POL1 and a second elevation power combiner/divider network 355-b associated with POL2. Each of the elevation power combiner/divider networks 355 may be an M:1 combiner/divider network including an elevation stage common port and M elevation ports 365. Thus, the first elevation power combiner/divider network 355-a may have M elevation ports 365-a associated with POL1 and the second elevation power combiner/divider network 355-b may have M elevation ports 365-b associated with POL2. The elevation power combiner/divider networks 355 may be of the corporate type and may include equal (e.g., substantially equal to manufacturing tolerances) waveguide path lengths (e.g., equal phases) between the elevation stage common port and each of the M elevation ports.
The waveguide device 305 includes M azimuth combiner/divider stages 345, each coupled with one set of the M elevation ports 365. Each azimuth combiner/divider stage 345 includes an N:1 azimuth combiner/divider 335 for each basis polarization and N unit cells 320-a (e.g., unit cells 320-a-1, 320-a-2, . . . 320-a-n, etc.). The azimuth combiner/divider 335 may be of the corporate type and may include substantially equal waveguide path lengths (e.g., equal phases) between the elevation port 365 for each basis polarization and each of the common waveguides 340-a, 350-a for the N unit cells 320-a (e.g., common waveguides 340-a-1, 350-a-1 for unit cell 320-a-1, etc.).
Each unit cell 320-a may include A antenna elements 225-a (only one antenna element is labeled in
Thus, each azimuth combiner/divider stage 345 may include N sub-arrays of A antenna elements. The waveguide device 305 may therefore include M·N·A antenna elements 225-a. In some cases, however, some azimuth combiner/divider stages 345 may include less than N unit cells 320-a. For example, to reduce the swept profile of the antenna subsystem 300, some of the azimuth combiner/divider stages 345 (e.g., towards the top and/or bottom) may include fewer unit cells 320-a, resulting in a taper or rounding of the corners of the waveguide device 305 that reduces the size of a radome used for the dual-polarized antenna.
The unit cells 320-a may be configured with a small inter-element distance (e.g., less than or equal to one wavelength at the highest operating frequency, etc.) between antenna elements 225-a and may be configured to be placed adjacent to other unit cells 320-a such that antenna elements 225-a of adjacent unit cells 320-a have the same inter-element distance between each other as antenna elements 225-a within each unit cell 320-a. This allows row/column scalability of the waveguide device 305 as the unit cells 320-a can be arranged in an arbitrary array size without changing the unit cell design.
The antenna subsystem 300 includes one or more transceivers 370 for bi-directional operation. The transceiver(s) convert electrical signals between an electrically conductive medium and a waveguide medium. The antenna subsystem 300 may be capable of full duplex operation. In some cases, the antenna subsystem 300 may include a single transceiver and may have predetermined polarization directionality (e.g., POL1 for transmission and POL2 for reception). As illustrated in
As shown in
Waveguide network 400 may illustrate the waveguide network for basis polarization POL1 for an azimuth combiner/divider stage 345 of
Each antenna element 225-b may have an individual waveguide 220-b with a rectangular cross-section. For efficiency and performance, each individual waveguide 325 may support dual-polarized operation. For example, when a signal is transmitted via dual-polarized antenna 140-b using a first polarization, it may be desired that all individual waveguides 220-b in the antenna 140-b are part of the beamforming network transmitting the signal. Similarly, when a signal wave is received by dual-polarized antenna 140-b of the same polarization or a different (e.g., orthogonal) polarization, it may be desired that energy received by all individual waveguides 220-b is combined in the beamforming network for the received signal power. In some cases, each individual waveguide 220-b may transmit energy using a first polarization and receive energy of a second (e.g., orthogonal) polarization concurrently. Each antenna element 225-b may include a polarizer and divided waveguides 210-b, 215-b associated with each basis polarization, of which only one antenna element 225-b has the divided waveguides 210-b, 215-b labeled for clarity.
The individual waveguides 220-b may have inter-element distances ΔEX 540 and ΔEY 545, which may be related to the desired operational frequency range and may be equal to each other. For example, ΔEX 540 and ΔEY 545 may be related to the wavelength at the highest operating frequency (e.g., to provide grating lobe free operation at the highest operating frequency, etc.). Each individual waveguide 220-b shares waveguide walls with at least two other individual waveguides 220-b, and the individual waveguides 220-b may have a width dAX 550 and height dAY 555, which may be determined by the inter-element distances ΔEX 540 and ΔEY 545 and a thickness ΔT 525 of the waveguide walls that is sufficient for structural integrity of the individual waveguides 220-b. In addition, the individual waveguides 220-b of adjacent antenna elements 225-b of adjacent unit cells 320-c share waveguide walls with each other.
Each unit cell 320-c may be a quad-element unit cell having a 4:1 power combiner/divider ratio for each basis polarization between the divided waveguides 210-b, 210-c of the antenna elements 225-b and common waveguides associated with each of the basis polarizations. The antenna elements 225-b may have inter-element distances ΔEX 540 and ΔEY 545, which may be the same distance for adjacent antenna elements 225-b within the same unit cell 320-c and for adjacent antenna elements 225-b that belong to adjacent unit cells 320-c. For example, the inter-element distance ΔEX 540 between antenna elements 225-b-1 and 225-b-2 may be the same as the inter-element distance ΔEX 540 between antenna elements 225-b-2 and 225-b-3.
To achieve the same inter-element distances ΔEX 540 and ΔEY 545 between antenna elements across the dual-polarized antenna 140-b, each quad element unit cell 320-c may have a unit cell boundary 530 with width dUX 560 given by dUX=2·ΔEX, and height dUY 565 given by dUY=2·ΔEY, where ΔEX 540 and ΔEY 545 may be small relative to the operating frequency range (e.g., less than or equal to one wavelength at the highest operating frequency, etc.). Thus, each quad element unit cell 320-c may have 4:1 power combiner/divider waveguide networks that connect the divided waveguides 210-b, 215-b of the antenna elements 225-b to the common waveguides associated with each of the basis polarizations that are within a rectangular prism formed by a projection of the unit-cell boundary 530 in a direction normal to the cross-sectional plane of the unit cell boundary 530 (e.g., into the page in
The wall thickness ΔT 525 may be relatively small (e.g., less than 0.2, 0.15, or 0.1 of the inter-element distances ΔEX 540 and ΔEY 545, etc.). Thus, the ratio of the unit cell cross-sectional width dUX 560 or height dUY 565 to the individual waveguide width dAX 550 or height dAY 555, may be less than 2.5. However, the ratio may be different for different individual waveguide widths dAX 550 or heights dAY 555, and may generally be smaller for antenna elements 225-b supporting lower frequencies (e.g., having larger individual waveguides 220-b). In one embodiment, a quad-element unit cell with dUX=dUY=0.735″ and using ridged waveguides (e.g., as shown in
As illustrated in diagram 600-c, unit cell 320-d may include a first waveguide network 605-a that includes multiple waveguide combiner/dividers and connects the divided waveguides A1210-c-1, B1210-c-2, C1210-c-3, and D1210-c-4 to a first common waveguide E1340-b associated with POL1 via continuous waveguide signal paths. Unit cell 320-d may include a second waveguide network 605-b that includes multiple waveguide combiner/dividers and connects the divided waveguides A2215-c-1, B2215-c-2, C2215-c-3, and D2215-c-4 to a second common waveguide E2350-b associated with POL2 via continuous waveguide signal paths.
The first waveguide network 605-a may include a first combiner/divider J1640-a, which may be an E-plane combiner/divider (e.g., E-plane tee, E-plane septum, etc.). The first combiner/divider J1640-a may divide the first common waveguide E1340-b into intermediate waveguides 635-a and 635-b. The first waveguide network 605-a may include a set of second waveguide combiner/dividers J2-A 630-a and J2-B 630-b coupled between the intermediate waveguides 630-a and 635-b and the first divided waveguides 210-c of the antenna elements 225-c. The set of second waveguide combiner/dividers J2-A 630-a and J2-B 630-b may be E-plane or H-plane combiner/dividers.
Similarly, the second waveguide network 605-b may include a third combiner/divider K1640-b, which may be an E-plane combiner/divider (e.g., E-plane tee, E-plane septum, etc.). The third combiner/divider K1640-b may divide the first common waveguide E2350-b into intermediate waveguides 635-c and 635-d. The first waveguide network 605-b may include a set of fourth waveguide combiner/dividers K2-A 630-c and K2-B 630-d coupled between the intermediate waveguides 630-c and 635-d and the second divided waveguides 215-c of the antenna elements 225-c. The set of fourth waveguide combiner/dividers K2-A 630-c and K2-B 630-d may be E-plane or H-plane combiner/dividers.
Unit cell 320-e may include waveguide networks 705 connecting the divided waveguides 210-d, 215-d of antenna elements 225-d associated with first and second basis polarizations to a first common waveguide 340-c and a second common waveguide 350-c, respectively. Although illustrated in
Waveguide networks 705 may include multiple waveguide combiner/dividers which may be within a prism 765 formed by extruding or projecting the unit cell boundary 530-a along the Z-axis 790 without increasing the inter-element distances ΔEX1 540-a and ΔEY1 545-a. Thus, the waveguide networks 705 of unit cell 320-e provide for a 4:1 power combiner/divider stage that can be configured in an arrangement having the same inter-element distances ΔEX1 540-a and ΔEY1 545-a for adjacent antenna elements 225-d within the same unit cell 320-e and for adjacent antenna elements 225-d that belong to adjacent unit cells 320-e. Thus, a dual polarization antenna array of an appropriate or desired size may be constructed using waveguide networks to connect antenna waveguide ports to unit cell common waveguides 340-c and 350-c at connection ports 341-c and 351-c, respectively.
The first waveguide network may include a combiner/divider 740-a dividing the first common waveguide 340-c into a first pair of intermediate waveguides 735-a and 735-b. The second waveguide network may include a combiner/divider 740-b dividing the second common waveguide 350-c into a second pair of intermediate waveguides 735-c and 735-d. In unit cell 320-e, the combiner/dividers 740-a and 740-b are E-plane combiner/dividers.
As can be seen in
In the direction of increasing Z from X-Y section plane 775, waveguide combiner/divider 730-a is coupled between intermediate waveguide 735-a and the divided waveguides 210-d of antenna elements 225-d-1 and 225-d-2 associated with the first basis polarization and waveguide combiner/divider 730-b is coupled between intermediate waveguide 735-b and the divided waveguides 210-d of antenna elements 225-d-3 and 225-d-4 associated with the first basis polarization. Similarly, waveguide combiner/divider 730-c is coupled between intermediate waveguide 735-c and the divided waveguides 215-d of antenna elements 225-d-1 and 225-d-2 associated with the second basis polarization and waveguide combiner/divider 730-d is coupled between intermediate waveguide 735-d and the divided waveguides 215-d of antenna elements 225-d-3 and 225-d-4 associated with the second basis polarization.
Additional H-plane bend sections and transition regions are used between the waveguide combiner/dividers 730 and the divided waveguides of the antenna elements 225-d to separate the waveguides in the H-plane and increase the waveguide height to match the height of the divided waveguides 210-d, 215-d at the antenna elements 225-d. The height of the divided waveguides 210-d, 215-d at the antenna elements 225-d may be approximately the same (e.g., approximately or within manufacturing tolerances) as the height of the corresponding common waveguide 340-c or 350-c.
As illustrated in
Returning to
Unit cell 320-f may include waveguide networks 805 connecting the divided waveguides 210-e of antenna elements 225-e associated with a first basis polarization to a first common waveguide 340-d and connecting the divided waveguides 215-e of antenna elements 225-e associated with a second basis polarization to a second common waveguide 350-d. The first common waveguide 340-d and the second common waveguide 350-d may be offset in two dimensions (e.g., along the X axis 870 and the Y-axis 880) with respect to each other.
Waveguide networks 805 may include multiple waveguide combiner/dividers which may be within a prism 765-a formed by extruding or projecting the unit cell boundary 530-b along the Z-axis 890. Thus, the waveguide networks 805 of unit cell 320-f provide for a 4:1 power combiner/divider stage that can be configured in an arrangement having the same inter-element distances ΔEX2 540-b and ΔEY2 545-b for adjacent antenna elements 225-e within the same unit cell 320-f and for adjacent antenna elements 225-e that belong to adjacent unit cells 320-f. Thus, a dual-polarized antenna array of an appropriate or desired size may be constructed using waveguide networks to connect antenna waveguide ports to unit cell common waveguides 340-d and 350-d at connection ports 341-d and 351-d, respectively.
The first waveguide network may include a combiner/divider 840-a dividing the first common waveguide 340-d into intermediate waveguides 835-a and 835-b. The second waveguide network may include a combiner/divider 840-b dividing the second common waveguide 350-d into intermediate waveguides 835-c and 835-d. In unit cell 320-f, the combiner/dividers 840-a and 840-b are E-plane combiner/dividers (e.g., E-plane T-junctions).
As shown in
In the direction of increasing Z from X-Y section plane 875, waveguide combiner/divider 830-a is coupled between intermediate waveguide 835-a and the divided waveguides 210-e of antenna elements 225-e-1 and 225-e-2 associated with the first basis polarization and waveguide combiner/divider 830-b is coupled between intermediate waveguide 835-b and the divided waveguides 210-e of antenna elements 225-e-3 and 225-e-4 associated with the first basis polarization. Similarly, waveguide combiner/divider 830-c is coupled between intermediate waveguide 835-c and the divided waveguides 215-e of antenna elements 225-e-1 and 225-e-2 associated with the second basis polarization and waveguide combiner/divider 830-d is coupled between intermediate waveguide 835-d and the divided waveguides 215-e of antenna elements 225-e-3 and 225-e-4 associated with the second basis polarization. As illustrated in
In some embodiments, unit cell 320-f may include one or more ridged waveguide sections. For example,
In some examples, antenna elements 225-e may include dielectric elements 855, which may increase an operational bandwidth of the antenna elements 225-e, improve impedance matching for signal propagation between the intermediate waveguides 835, the divided waveguides 210-e, 215-e, and the individual waveguide of the antenna elements 225-e, and improve impedance matching for signal propagation between the individual waveguide of the antenna elements 225-e and free space. In some cases, the dielectric elements 855 may effectively reduce a lower cutoff frequency of the individual waveguide of antenna elements 225-e. The dielectric elements 855 may also assist in matching the propagation constants between the ridged waveguides 835 and the antenna elements 225-e of a specific individual waveguide cross-sectional size.
In some embodiments, unit cell 320-f includes ridge transition region 845, which includes waveguide transition features for transitioning from the ridge-loading in intermediate waveguides 835 to the non-ridged antenna elements 225-e. The waveguide transition features may include decreasing steps of ridge depth and may include increases in width of the ridges as the depth is decreased. In some examples, dielectric elements 855 include transition features for transitioning from ridge-loading to dielectric loading in antenna elements 225-e. The waveguide transition features may be matched or complementary with the transition features of the dielectric elements 855.
In some examples, ridge loading may lower a cutoff frequency for the same waveguide width. Thus, the ridge loading and dielectric elements 855 illustrated in
In some examples of dual-polarized antennas 140 employing the unit cells 320-e of
As shown in exploded views 900-a and 900-b, dual-polarized antenna 140-c may have a close-out layer 910, which may be a suitable material for keeping dust and other particles out of the waveguide devices of dual-polarized antenna 140-c while not adversely impacting the electrical properties of waves transmitted and received by dual-polarized antenna 140-c. In some examples, close-out layer 910 is approximately 10 thousandths of an inch thick and is made from a material having a dielectric constant that is similar to dielectric assemblies 885. In one example, close-out layer 910 is made from a woven glass PTFE resin.
As can be seen in exploded view 900-b, dielectric assembly 885-b includes dielectric elements for two antenna elements of dual-polarized antenna 140-c and is inserted into the antenna elements prior to covering with close-out layer 910.
The waveguide device 1005 includes waveguide networks connecting transmission port 1010-a and reception port 1015-a associated with a first basis polarization POL1 with a set of first common waveguides 1040 for each of the unit cells (only one first common waveguide 1040 labeled for clarity) of the dual-polarized antenna 140-d. The waveguide device 1005 also includes waveguide networks connecting transmission port 1010-b and reception port 1015-b associated with a second basis polarization POL2 with a set of second common waveguides 1050 (only one second common waveguide 1050 labeled for clarity) for each of the unit cells of the antenna 140-b.
The waveguide device 1005 includes a first elevation power combiner/divider network 1055-a associated with POL1 and a second elevation power combiner/divider network 1055-b associated with POL2. The first elevation power combiner/divider network 1055-a may have M elevation ports 1065-a (only one elevation port 1065-a labeled for clarity) associated with POL1 and the second elevation power combiner/divider network 1055-b may have M elevation ports 1065-b (only one elevation port 1065-a labeled for clarity) associated with POL2. The elevation power combiner/divider networks 1055 may be of the corporate type and may include equal (e.g., substantially equal to manufacturing tolerances) waveguide path lengths (e.g., equal phases) between the elevation stage common port and each of the M elevation ports. In the illustrated example, M=8. However, other designs including more or fewer elevation ports may be constructed using similar waveguide configurations.
The waveguide device 1005 includes M azimuth combiner/dividers 1035 associated with each of the first and second basis polarizations POL1 and POL2. Each azimuth combiner/divider 1035 may connect an elevation port 1065 to N common waveguides 1040, 1050 associated with one of the first and second basis polarizations POL1 and POL2. The azimuth combiner/divider 1035 may be of the corporate type and may include substantially equal waveguide path lengths (e.g., equal phases) between the corresponding elevation port 1065 and each of the N azimuth ports for each basis polarization.
The waveguide device 1005 may also include M·N unit cells 320-g. Thus, the waveguide device 1005 may include an M·N combiner/divider feeding N unit cells 320-g, to result in an antenna with M·N·A antenna elements. In the illustrated example, M=8, N=40, and A=4. Thus,
In some examples, the layers 1110 are machined aluminum waveguide sub-assemblies. The machined waveguide sub-assemblies 1110 may be vacuum brazed together to form the waveguide device 1105.
The detailed description set forth above in connection with the appended drawings describes exemplary embodiments and does not represent the only embodiments that may be implemented or that are within the scope of the claims. The term “example” used throughout this description means “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other embodiments.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described embodiments.
Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
The functions described herein may be implemented in various ways, with different materials, features, shapes, sizes, or the like. Other examples and implementations are within the scope of the disclosure and appended claims. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of”) indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).
As used in the present disclosure, the term “parallel” is not intended to suggest a limitation to precise geometric parallelism. For instance, the term “parallel” as used in the present disclosure is intended to include typical deviations from geometric parallelism relating to such considerations as, for example, manufacturing and assembly tolerances.
Furthermore, certain manufacturing process such as molding or casting may require positive or negative drafting, edge chamfers and/or fillets, or other features to facilitate any of the manufacturing, assembly, or operation of various components, in which case certain surfaces may not be geometrically parallel, but may be parallel in the context of the present disclosure.
Similarly, as used in the present disclosure, the terms “orthogonal” and “perpendicular”, when used to describe geometric relationships, are not intended to suggest a limitation to precise geometric perpendicularity. For instance, the terms “orthogonal” and “perpendicular” as used in the present disclosure are intended to include typical deviations from geometric perpendicularity relating to such considerations as, for example, manufacturing and assembly tolerances. Furthermore, certain manufacturing process such as molding or casting may require positive or negative drafting, edge chamfers and/or fillets, or other features to facilitate any of the manufacturing, assembly, or operation of various components, in which case certain surfaces may not be geometrically perpendicular, but may be perpendicular in the context of the present disclosure.
As used in the present disclosure, the term “orthogonal,” when used to describe electromagnetic polarizations, is meant to distinguish two polarizations that are separable. For instance, two linear polarizations that have unit vector directions that are separated by 90 degrees can be considered orthogonal. For circular polarizations, two polarizations are considered orthogonal when they share a direction of propagation, but are rotating in opposite directions.
The previous description of the disclosure is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The present application is a continuation of U.S. patent application Ser. No. 15/398,640 by Jensen, et al., entitled “Compact Waveguide Power Combiner/Divider for Dual-Polarized Antenna Elements,” filed Jan. 4, 2017, which is a continuation of U.S. patent application Ser. No. 14/835,252 by Jensen, et al., entitled “Compact Waveguide Power Combiner/Divider for Dual-Polarized Antenna Elements,” filed Aug. 25, 2015, the entirety of which is incorporated herein by reference for any and all purposes.
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| Number | Date | Country | |
|---|---|---|---|
| Parent | 15398640 | Jan 2017 | US |
| Child | 15845780 | US | |
| Parent | 14835252 | Aug 2015 | US |
| Child | 15398640 | US |
