MXPA98003538A - Compact microwave terrestrial radio utilizing monolithic microwave integrated circuits - Google Patents

Abstract

An integrated point-to-point microwave radio frequency unit/antenna (60) has a housing (62), a microwave antenna (68) affixed to the front face of the housing (62), and a microwave radio frequency transceiver electronics package (66) within the housing (62). The transceiver electronics package (66) includes a circuit board having transmitter and receiver intermediate frequency processors (124, 138). The transceiver electronics package (66) further includes a microwave transmitter (102) and a microwave receiver (104), each utilizing monolithic microwave integrated circuit architecture. The signals of the microwave transmitter (102) and microwave receiver (104) are preferably of different frequencies and are diplexed for communication with the antenna (68).

Description

COMPACT MICROWAVE TERRESTRIAL RADIO USING INTEGRATED MONOLITHIC MICROWAVE CIRCUITS BACKGROUND OF THE INVENTION This invention relates to microwave radios and, more particularly, to a radiofrequency unit for a microwave radio. Microwave radiocommunications are widely used for the transfer of large amounts of data, such as in terrestrial and space microwave long distance communication links. They are also of interest for shorter-range, lower-power applications, such as basic voice, video and data links between a cellular base station and a central telephone office. In such applications, the microwave transmission distance is typically about 1 / 2-5 miles, the microwave signal is at a specific frequency in the range of about 2-94 GHz, and the power output of the microwave transmitter It is approximately 100 milliwatts. Such microwave communication systems are generally called "point-to-point" systems. Corresponding to high power microwave communication systems, a conventional point-to-point system has three basic physical parts: a signal processing unit (SPU), sometimes called an "inside" unit that has baseband radio components, a radio frequency (RF) unit (RFU), sometimes called an "outside" unit that has microwave frequency radio components, and an antenna. Because microwave power is required between the components operating at a microwave frequency, the radio frequency unit is located within a few feet of the antenna, which is ordinarily mounted on the outside and pointed to another terminal. point to point located at a certain distance. The antenna is typically a parabolic antenna of the Cassegrain type. The signal processing unit can be located at a considerable distance from the radio frequency unit. A set of ordinary coaxial cables extends between the signal processing unit and the radio frequency unit, but coaxial microwave power is required between the radiofrequency unit and the antenna. As point-to-point microwave systems become more popular, their physical packaging and aesthetic appearance become more important. Radiofrequency units and existing antennas are bulky, heavy, visually obstructive and, in many cases, difficult to assemble, align and maintain in alignment. With the proliferation of point-to-point systems in large cities, it has become more difficult to find new mounting spaces on existing masts and elsewhere. Installers must raise the radiofrequency unit and the antenna subsequently installed in increasingly precarious places in order to establish a line of visual contact with the remote terminal. The radiofrequency unit and the antenna must be mounted in close proximity to each other. To overcome these problems, the assignee of the present invention is developing a radio frequency unit and microwave antenna, point-to-point, integrated, which are much more compact, lighter weight and visually less obstructive than conventional systems . However, the size and weight of the microwave signal processing components provide a significant barrier to achieving these objectives, and according to the foregoing there is a need for such microwave signal processing components and an architecture that as a result, a smaller size and a lower weight. The present invention satisfies this need and further provides related advantages. SUMMARY OF THE INVENTION The present invention provides a radiofrequency unit and microwave antenna, from point to point, integrated, which are compact and lightweight. The package of microwave electronic components within the device is considerably smaller and lighter than in the existing microwave radiofrequency units, an important advantage that allows the entire radio frequency unit to become smaller and lighter. The radiofrequency unit that uses this approach is visually less obstructive, and easier to lift, assemble, align, and replace (if necessary) than conventional units. According to the invention, a radio frequency / microwave antenna, integrated point-to-point, comprises a microwave antenna having an input / output of the antenna, a housing, and a package of electronic transceiver components. microwave radiofrequency within the housing. The transceiver electronic component package comprises a transmitting intermediate frequency processor having a baseband frequency input and a microwave output, and a receiving intermediate frequency processor having a microwave input and a baseband frequency output. The transceiver electronic component package further includes a microwave transmitter and a microwave receiver, each having a monolithic microwave integrated circuit architecture. The microwave transmitter has an input in communication with the microwave output of the transmitting intermediate frequency processor and an output in microwave communication with the input / output power of the antenna. The microwave receiver has an input in communication with the input / output power of the antenna and an output in microwave communication with the microwave input of the receiving intermediate frequency processor. The transceiver electronic component package also preferably includes a diplexer between the antenna and the microwave transmitter and the microwave receiver, in order to allow simultaneous transmission and reception of the microwave signals at two different frequencies. Within the housing, a power supply and a controller for the transceiver electronic components package are also normally provided. In conventional microwave processing technology, discrete components are typically used in those parts of the signal processor that operate in the microwave frequency range. These discrete components and the voluminous waveguides that separate them result in heavy and bulky structures. In the present approach, monolithic microwave integrated circuit (M IC) technology has been used in microwave frequency circuits, transmitters and receivers, which process microwave signals. Accordingly, these circuits can be made in a modular form that is compact and light in weight. These features, in combination with the use of the preferred integrated flat antenna, allow the integrated point-to-point microwave radio frequency / antenna unit to have a rectangular prismatic shape of approximately 12 inches by approximately 12 inches by approximately 3 inches thick and weighing less than about 15 pounds. Therefore, the radio frequency unit and the integrated antenna are much easier to install in precarious places than the radio frequency units and conventional non-integrated parabolic antennas. The integrated radiofrequency unit and antenna are less antistatically objectionable than previous systems and require a smaller support structure. Other features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. However, the scope of the invention is not limited to this preferred embodiment. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram of a radio transmitter and microwave receiver; Figure 2 is a perspective view of a conventional radiofrequency unit and microwave antenna; Figure 3 is a perspective view of an integrated radiofrequency / antenna unit according to the invention; Figure 4 is a front elevational view, partially sectioned, of a radio frequency / antenna integrated unit, preferred, according to the invention; Figure 5 is an elevational, side, exploded view of the integrated radiofrequency / antenna unit of Figure 4, illustrating a typical component diagram; Figure 6 is a block diagram of electronic circuits of the preferred implementation of the radiofrequency unit; Figure 7 is a block diagram of electronic circuits of the preferred implementation of the transmitting IF processor; Figure 8 is a block diagram of electronic circuits of the preferred implementation of the receiver IF processor; Figure 9 is a block diagram of electronic circuits of the preferred implementation of the microwave frequency transmitter module; Figure 10 is a block diagram of electronic circuits of the preferred implementation of the microwave frequency receiver module; and Figure 11 is a schematic perspective view of a conventional radiofrequency and antenna unit and an integrated radiofrequency / antenna unit mounted on a mast. DETAILED DESCRIPTION OF THE INVENTION Figure 1 is a schematic diagram of a microwave radio transceiver system 20. The electronic structure in general of such systems 20 as shown in Figure 1 is known in the art and is described in greater detail, for example , in "Components of RF for PCS Base Stations ", published by Strategies Unlimited, 1996. The present invention resides in part in an improved architecture for the implementation of this basic approach to electronic components System 20 includes a signal processing unit 22 (also known as the "indoor unit") that processes the baseband signals, a radiofrequency unit 24 (also known as the "outdoor unit") that processes the microwave signals, and a microwave antenna 26. The signal processing unit 22 has an input / output of voice, video, and / or data link information through a cable 28. This information is processed through baseband circuitry 30 and a modulator / demodulator 32. An controller 34 and a power supply 36. The signal processing unit 22 communicates with the radio frequency unit 24 at low frequencies through a conventional signal cable 38. The radio frequency unit 24 includes a microwave transceiver 40 which includes circuitry for both intermediate frequency processing and microwave frequency processing within a narrower range selected from the wide band ranging from about 2 to about 94 GHz (Gigahertz), by converting the low frequency signal operable in the signal processing unit 22. The implementation of the architecture of the radio frequency unit 24 is a key feature of the invention and will be discussed in greater detail subsequently. . A controller 42 and a power supply 44 are also provided within the radio frequency unit 24.

The microwave transceiver 40 has an antenna connection 46 to which a microwave radio frequency feed 48 is connected in order to provide a signal to the antenna 26, or in order to receive a signal from the antenna 26. The power 48 is typically a coaxial cable or a waveguide that can not be more than a few feet in length without suffering a substantial attenuation of the signal. Figure 2 illustrates the implementation of a conventional radiofrequency unit 24 and antenna 26, above, connected to microwave power 48, which uses the electronic component approach of Figure 1. Radio frequency unit 24 typically has measurements 12 inches by 12 inches by 12 inches and weights of approximately 35 pounds. The antenna 26 is a Cassegrain satellite dish having a disk diameter of approximately 12 inches or more and a weight of approximately 15 pounds. Both components must be mounted in one place in such a way that the antenna 26 can be pointed to a similar terminal but located remotely. The installer must find a way to mount the antenna 26 so that it aligns with the antenna of the remote unit, and mount the radiofrequency unit 24 so that it is secured even within the range allowed by the length of the power supply. microwave 48. Other versions of the previous approach of figure 2 are known in which the satellite dish is fixed directly to the radio frequency unit, but such a combined approach remains difficult to handle and weighed. Figure 3 shows an integrated radiofrequency / antenna unit of the present invention in perspective view. Figure 4 illustrates a preferred form of the present invention in an exterior, elevational, front, partially sectioned view, and Figure 5 is an exploded side view of the preferred apparatus. This apparatus uses the general electronic component approach of Figure 1, but with a different architecture and an antenna that offers important advantages. An integrated radiofrequency / antenna unit 60 includes a housing 62 having an outer wall 64. A handle 65, which is integral or removable, extends from the housing 62 and allows the radiofrequency / antenna unit 60 to be easily transported. A package of radio frequency microwave transceiver electronic components 66 is fixed within the housing 62. The electronic component package 66 includes the microwave transceiver 40., the controller 42 and the power supply 44. Part of the outer wall 64 is formed as an integral flat antenna 68. The planar antenna 68 may be formed separately and attached to the wall 64, as illustrated, or may be formed as a part of the wall itself. That portion of the wall 64 that is not the antenna 68 can be made of any feasible material, such as a metal or a plastic. A dome 70 in the form of a plastic sheet is mounted on the face of the flat antenna 68 to protect it. The planar antenna 68 is preferably a continuous transverse short antenna (CTS). The CTS microwave antenna is known in the art and is described, for example, in U.S. Patent 5,266,961, the disclosure of which is incorporated herein by reference. In general terms, and as illustrated in Figures 3 and 5, the CTS antenna has a dielectric element with a first portion and a second portion extending generally transverse to the first portion. The second portion forms a transverse protrusion projecting from a first surface of the first portion. A first conductive element is placed coextensively with the dielectric element along a second surface of the first portion. A second conductive element is positioned along the first surface of the dielectric element and is along the transversely extending wall edges formed by the second portion of the dielectric element. Additional construction details are set forth in the '961 patent.

The CTS antenna has particular advantages when used in the present application. The CTS antenna is flat, small in lateral dimensions and thickness and light in weight. The output signal of the CTS antenna can be oriented slightly electronically. During assembly, the radiofrequency / antenna unit 60 should generally be aligned to the remote unit with which communication is established. However, the alignment can be interrupted slightly due to climatic or temperature effects in the mounting structure. In that case, the small deviation from the proper alignment can be compensated for electronically maintaining a high signal resistance directed at the remote unit. The integrated radiofrequency / antenna unit 60 has an antenna connection and a radio frequency microwave power cable extending from the antenna connection to the back of the flat antenna 68, although the connection of the antenna and the cable Feeding are not visible in Figures 3-5. The radiofrequency feed is at most 1-2 inches long and is contained entirely within the housing 62. There is very small microwave attenuation as the signal passes through this short feed. The installer is only required to place and fix in its place the only integrated radio frequency / antenna unit 60, and does not worry about moving and placing two units in a compatible manner. Figures 6-10 illustrate the implementation of the electronic circuitry of the radiofrequency unit 24. Figure 6 shows the complete circuit, and Figures 7-10 illustrate the transmitting IF processor, the receiving IF processor, the transmitting module of microwave frequency, and microwave frequency receiver module, respectively. The main function of this circuitry is to communicate the signal information between the antenna 68, operating at approximately 37-40 GHz in the preferred embodiment, and the signal processing unit 22 operating at approximately 70-310 MHz in the preferred embodiment. This communication requires upward changes and downward changes in the frequency of the signal. As seen in Figure 6, the electronic circuitry of the radio frequency unit 24 includes an IF processor card 100 that communicates on its low frequency side through a multiplexer 101 with the signal processing unit 22 on the communication cable 38. The high frequency side of the IF processor card 100 communicates with a microwave transmitter module 102 and a microwave receiver module 104. These microwave frequency modules 102 and 104, which operate at different frequencies, communicate with the CTS antenna 68 through a diplexer 106. The diplexer 106, a known device, contains filters that allow the simultaneous transmission and reception of the microwave signals of different frequencies. The constant frequency signals required in the signal processing are synthesized in a synthesizer card 108, which includes a transmitter synthesizer 110, a receiver synthesizer 112 and a common local oscillator synthesizer (LO) 114. The control and power functions are supplied from a control / power card 116, which includes a central processing unit 118, a power supply 120 and a telemetry unit 122. The telemetry unit 122 monitors and reports the states of the radio frequency unit 24. to the signal processing unit 22 and receiving the command signals from the signal processing unit 22. The central processing unit 118 monitors and reports the status of the radio frequency unit 24 to the telemetry unit 122 and also controls functions such as automatic gain and leveling, maintenance of transmitter output power at a constant level and maintain the emission of receiving signals at a constant level. Figure 7 illustrates the components of a transmitting IF processor 124 on the IF processor card 100. The signals to be transmitted by microwaves are received from the signal processing unit 22., at 310 MHz in the preferred mode. The input signals are amplified as necessary by an amplifier 126. The output signal of the amplifier is mixed by a mixer 128 with the signal produced by the LO synthesizer 114 to create the intermediate frequency signal which is filtered by a filter 130. and amplified as necessary by an amplifier 132. The amplified signal is mixed in a mixer 134 with the signal produced by the transmitting synthesizer 110 in order to create another intermediate frequency signal that is filtered by a filter 136. The output signal end is provided to the transmitter module 102. In the preferred embodiment, the output is a signal in the range of about 5 GHz. A receiver IF processor 138 operates in a manner similar to the transmitting IF processor 124, except that it reduces the frequencies. As shown in Figure 8, the signals received by the microwave transmission are provided from the receiver module 104, at about 5 GHz in the preferred embodiment. The input signals are amplified as necessary by an amplifier 140. The output of the amplifier 140 is filtered by a filter 142 and then mixed in a mixer 144 with the output signal of the receiver synthesizer 112. The mixed signal is amplified by a amplifier 146, is filtered by a filter 148 and mixed with the output signal of the LO synthesizer 114 by a mixer 150. The mixed signal is filtered by a filter 152 and amplified by an amplifier 154. In the preferred embodiment, the The output is a signal in the 70 MHz range and is fed to the signal processing unit 22 on the cable 38. All the components of the IF processors 124 and 138 are known or commercially available. In a prototype embodiment of the invention, the amplifiers are preferably RF2304 amplifiers made by RF Microdevices, the filters are ceramic resonant filters manufactured by Lar Engineering and the mixers are dually balanced mixers made by RF Prime. These components are placed on the printed circuit board of the IF processor card 100 mounted within the housing 62 and interconnected in the manner illustrated. Figure 9 illustrates the components of the microwave transmitter module 102. A mixing signal is generated by providing a transmitting LO input 160 from the transmitting synthesizer 110. In the preferred embodiment, the transmitting LO 160 input is about 3.5-3.9. GHz. The input of transmitting LO 160 is amplified as necessary by an amplifier 162, the frequency multiplied by an integer factor 3 in the preferred embodiment, by a frequency multiplier 164, filtered to remove unwanted frequency components by a filter harmonic 166, amplified as necessary by an amplifier 168, again the frequency is multiplied by an integer factor 3 in the preferred embodiment, by a frequency multiplier 170, amplified as necessary by an amplifier 172 and filtered again to remove unwanted frequency components by a harmonic filter 174. In the preferred embodiment, the output of the harmonic filter 174 is at approximately 32 GHz. A transmitting IF input 176 is supplied from the transmitting IF processor as the output of the filter 138, at about 5 GHz in the preferred embodiment. The input signal 176 is mixed with the output of the harmonic filter 174 in a mixer 180, filtered to remove the sideband components in a filter 182, amplified as necessary by an amplifier 184, filtered again by sideband in a filter 186 is amplified as necessary by an amplifier 188 and the frequency is filtered by a filter 190 to obtain a single frequency output signal that is provided as an input to the diplexer 106. In the preferred embodiment, the output of the filter 190 is selectable within the range of 37-40 GHz. The microwave receiver module 104, illustrated in FIG. 10, operates in a manner similar to the microwave transmitter module. A receiving LO input 200 generated by the receiving synthesizer 112 is amplified as necessary by an amplifier 202, the frequency is multiplied by a constant integer 3 in the preferred embodiment, by a frequency multiplier 204, filtered to remove the components of frequency different from those desired by a harmonic filter 206, it is again amplified as necessary by an amplifier 208, the frequency is again multiplied by a constant integer 3 in the preferred embodiment, by means of a frequency multiplier 210, amplified as necessary by an amplifier 212 and is filtered again to remove the frequency components different from those desired by a harmonic filter 214. In the preferred embodiment, the receiving LO input 200 is approximately 3.5-3.9 GHz and the output of the harmonic filter 214 is approximately 32 GHz.

A receiving input 216 is received from the diplexer 106. In a preferred embodiment, the receiving input 216 is at approximately 37-40 GHz. That signal is amplified as necessary by an amplifier 218, the image is filtered by a filter 220. to remove the image components (at 27-30 GHz in the preferred embodiment), and mix it with the output signal of the harmonic filter 214 in a mixer 222. The output signal of the mixer 222 is at a frequency that is the difference between that of the input signal 216 and the output of mixing signals from the harmonic filter 214, in the preferred case of about 5 GHz. This signal is amplified as necessary by an amplifier 224 and is supplied as the input 48 to the receiver IF processor 140. The transmitter module 102, the receiver module 104 and the diplexer 106 are implemented by use of the monolithic microwave integrated circuit (MMIC) architecture. This integrated circuit approach for microwave circuits and their processing procedures are generally known in the art for other applications and are described for example in George Vendelin, "Microwave Circuit Design Using Linear and Nonlinear Techniques", John Wiley , 1990. U.S. Patents 4,837,530; 4, 890, 077; 4, 947, 136; ,319,329, whose exposures are incorporated for reference, describe the use of MMIC techniques. Commercial components that use MMIC technology are available, such as various amplifiers developed by Alpha Industries. In this approach, the components of Figures 9 and 10 are fabricated as thin film elements, preferably based on gallium-arsenide technology, separated by tracking-type waveguides instead of conventional hollow waveguides or of flat line. Figure 11, which is schematic and not drawn to scale, illustrates the assembly of a conventional radiofrequency unit 80 and its antenna 82, connected by its microwave power 84, on a mast 86. Also shown is a radio frequency unit / integrated antenna 60 of the invention. The integrated radiofrequency unit / antenna 60 has a mounting bracket 88 attached to one of the different outer walls 64 to which the integrated flat antenna 68 is attached and the mounting bracket allows direct quick adjustable attachment to the mast 86. It is apparent that the approach of the invention is much more convenient for installation and alignment than the conventional approach. The integrated radiofrequency / antenna unit 60 can also be mounted in locations and locations that are largely unusable with the conventional device. For example, the integrated radiofrequency / antenna unit 60 is easily mounted on a window structure in much the same way as the ambient air conditioner. The inventors have developed a prototype design for the integrated radiofrequency / antenna unit 60, shown in Figures 3-5, for operation at a microwave frequency of 37-40 GHz, by e-1 using the approach of the invention. The flat antenna has an amplitude W of approximately 10-1 / 2 inches, a length L of approximately 10-1 / 2 inches and a thickness TA of approximately 1 inch. The remaining components, the microwave transceiver 40, the controller 42 and the power supply 44 are set in a housing having the same length and amplitude and a thickness TB of approximately 2 inches. The total size of the housing and antenna package is approximately 12 inches by 12 inches by 3 inches. The weight of the integrated radiofrequency / antenna unit 60 is approximately 13 pounds. It is desirable that the weight of the radiofrequency / antenna unit be less than about 15 pounds, so that it is easily lifted and operated by an installer. Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and improvements can be made without departing from the spirit and scope of the invention. According to the foregoing, the invention is not limited except by the appended claims.

Claims (10)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. An integrated radio-frequency / microwave antenna unit, characterized in that it comprises: a microwave antenna having an input / output power of the antenna; accommodation; a package of microwave radio frequency transceiver electronic components within the housing, the transceiver electronic component package comprising a transmitting intermediate frequency processor having a baseband frequency input and a microwave output, a receiving intermediate frequency processor having a microwave input and a baseband frequency output, a microwave transmitter having a monolithic microwave integrated circuit architecture, the microwave transmitter having an input in communication with the microwave output of the transmitting intermediate frequency processor and a output in microwave communication with the input / output power of the antenna; and a microwave receiver having a monolithic microwave integrated circuit architecture, the microwave receiver having an input in communication with the input / output power of the antenna and an output in microwave communication with the microwave input of the processor. receiving intermediate frequency. The integrated radiofrequency / microwave antenna unit, according to claim 1, characterized in that it further includes: a microwave diplexer having a monolithic microwave integrated circuit architecture having the microwave diplexer as an input / output to the input / output of the antenna, as an input to the microwave transmitter output and as an output to the microwave receiver input. The integrated radiofrequency / microwave antenna unit, according to claim 1, characterized in that it also includes: a supply of energy inside the housing, the power supply having power conductors towards the intermediate frequency processor transmitter, the receiving intermediate frequency processor, the microwave transmitter and the microwave receiver. The integrated radiofrequency / microwave antenna unit, according to claim 1, characterized in that it also includes: a controller inside the housing, the controller being in communication with the transmitting intermediate frequency processor, the processor receiving intermediate frequency, the microwave transmitter and the microwave receiver. The integrated radio-frequency / microwave antenna unit according to claim 1, characterized in that the transmitting intermediate frequency processor comprises at least one frequency mixer operable to increase the frequency of the band frequency input base, at least one filter in series with the frequency mixer and at least one amplifier in series with the filter. 6. The integrated radio-frequency / microwave antenna unit, according to claim 1, characterized in that the receiving intermediate frequency processor comprises at least one frequency mixer operable to decrease the frequency of the microwave input, less a filter in series with the frequency mixer and at least one amplifier in series with the filter. The integrated radiofrequency / microwave antenna unit, according to claim 1, characterized in that the microwave transmitter comprises at least one frequency mixer operable to increase the frequency of the microwave output of the frequency processor intermediate transmitter, at least one filter in series with the frequency mixer and at least one amplifier in series with the filter. 8. The radiofrequency unit / microwave antenna, integrated point-to-point, according to claim 1, characterized in that the microwave receiver comprises at least one frequency mixer operable to decrease the frequency of the input / output power of the antenna, at least one filter in series with the frequency mixer and at least one amplifier in series with the filter. The integrated radiofrequency / microwave antenna, according to claim 1, characterized in that the housing has a size of no more than about 12 inches by 12 inches by about 3 inches. The integrated radiofrequency / microwave antenna, according to claim 1, characterized in that the housing, the antenna and the package of electronic components together weigh less than about 15 pounds.