Complete outdoor radio unit for LMDS

• US 6,640,084 B2
• Filed: 11/29/2000
• Issued: 10/28/2003
• Est. Priority Date: 02/01/2000
• Status: Expired due to Fees

• Current Assignee: Synoptel Corp (Solomon Alliance Group, Inc.)
• Original Assignee: Synoptel Corp (Solomon Alliance Group, Inc.)
• Inventors: Funk, Eric, Nguyen, Tho, Nagabhushana, Sunil M., Phelps, Lee, Bawangaonwala, Ali I., Zheng, Guobao, Pande, Krishna
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): Lele, Tanmay
• Application Number:
  US09/725,240
• Publication Number:
  US 20020065052A1
• Time in Patent Office: 1,063 Days
• Field of Search: 455/3.01, 455/3.02, 455/3.05, 455/73, 455/90, 455/128, 455/130, 455/82, 455/78, 455/67.5, 219/208, 219/209, 361/688, 361/702, 361/703, 361/704, 361/705, 361/707, 361/708-712, 361/715-719
• US Class Current: 455/3.01
• CPC Class Codes: H01Q 1/02 Arrangements for de-icing; Arrangements for drying-out ; Arrangements for cooling; Arrangements for preventing corrosion
• CPC Class Codes: H01Q 13/0258 Orthomode horns orthomode transducers H01P1/161
• CPC Class Codes: H01Q 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them
• CPC Class Codes: H04H 40/90 specially adapted for satellite broadcast receiving
• CPC Class Codes: H05K 1/0237 High frequency adaptations H05K1/0216 takes precedence
• CPC Class Codes: H05K 1/142 Arrangements of planar printed circuit boards in the same plane, e.g. auxiliary printed circuit insert mounted in a main printed circuit
• CPC Class Codes: H05K 3/0058 Laminating printed circuit boards onto other substrates, e.g. metallic substrates H05K1/0281 takes precedence

Abstract

The complete outdoor radio unit for LMDS is a light weight, compact transceiver featuring planar circuitry. The transceiver uses cross polarization through an orthomodal transducer and frequency offset between transmit and receive to provide isolation between the transmitter and receiver. The transceiver includes three printed circuit boards directly attached by thermally conductive epoxy to a heat sink which forms part of the antenna dish/transceiver housing for effective heat transfer. Two of the waveguides are used as receiver and transmitter transmission lines into the orthomodal transducer, and two of the waveguides are used as bandpass filters. The transceiver also includes a DC—DC converter in the power supply which is modified to connect the base plate to the heat sink for compactness and improved heat transfer, and a frequency synthesizer with a phase locked loop hardwired to a single reference frequency for compact size.

Claims

1. A complete outdoor radio unit for the Local Multipoint Distribution Service having a transceiver adapted for mounting to a housing at a rear side of a dish antenna, the transceiver comprising:

a) a transmitter and a receiver operable to transmit and receive radio waves in the millimeter wavelength portion of the electromagnetic spectrum;

b) a heat sink having a planar inner surface with gold plated copper and an outer surface having fins, the heat sink forming a housing rear wall and being adapted for attachment to a housing at a rear side of a dish antenna in order to form an air tight and waterproof transceiver enclosure;

c) a power supply printed circuit board having a top surface with the power supply circuitry of said transceiver mounted thereon and a bottom surface defining a ground plane, the bottom surface being attached directly to said heat sink;

d) an L-band microwave printed circuit board having a top surface with microwave intermediate frequency circuitry mounted thereon and a bottom surface defining a ground plane, the bottom surface being attached directly to said heat sink;

e) a thermally and electrically conductive plate defining a millimeter ground plane, the millimeter ground plane being attached directly to said heat sink; and

f) a millimeter microwave printed circuit board having a top surface with microwave circuitry operable in the millimeter wavelength band mounted thereon and a bottom surface defining a ground plane, the bottom surface being directly attached to said millimeter ground plane, whereby said transceiver has a substantially planar configuration with all of said printed circuit boards connected to said heat sink by thermally conductive paths for effective heat transfer.

2. The complete outdoor radio unit according to claim 1, wherein:

a) said power supply printed circuit board and said L-band microwave printed circuit board are elastically attached to said heat sink by a thermally conductive epoxy; and

b) said millimeter microwave printed circuit board is elastically attached to said heat sink by a thermally conductive epoxy, whereby said printed circuit boards may expand and contract without breaking during heating and cooling.

3. The complete outdoor radio unit according to claim 1, wherein said millimeter ground plane has a first cavity defining a bottom portion of a first waveguide transmission line and a second cavity defining a bottom portion of a second waveguide transmission line, the second cavity being configured in a direction orthogonal to said first cavity, said transceiver further comprising:

a) an upper waveguide assembly mounted on said millimeter ground plane, said first and second waveguide transmission lines continuing through the upper waveguide assembly;

b) an orthomodal transducer mounted on said upper waveguide assembly, said first and second waveguide transmission lines communicating with said orthomode transducer to transmit and receive radio waves having orthogonal polarization; and

c) an antenna horn attached to said orthomodal transducer for transmitting and receiving radio waves, the antenna horn being adapted for insertion through an antenna dish.

4. The complete outdoor radio unit according to claim 3, wherein said millimeter microwave printed circuit board further comprises a transmitter launch point defined therein, the millimeter microwave printed circuit board being disposed between said millimeter ground plane and said upper waveguide housing with the transmitter launch point aligned in said first waveguide transmission line, the transmitter launch point having a first microstrip projecting into said first waveguide transmission line for introducing a signal to be transmitted into said first waveguide transmission line, the signal traveling through said first waveguide transmission line and said orthomodal transducer to said antenna horn, whereby the signal is transmitter without a wire feed line.

5. The complete outdoor radio unit according to claim 3, wherein said millimeter microwave printed circuit board further comprises a receiver launch point defined therein, the millimeter microwave printed circuit board being disposed between said millimeter ground plane and said upper waveguide housing with the receiver launch point aligned in said second waveguide transmission line, the receiver launch point having a second microstrip projecting into said second waveguide transmission line for receiving a signal received by said antenna horn and traveling through said orthomodal transducer and said second waveguide transmission line, whereby the signal is received without a wire feed line.

6. The complete outdoor radio unit according to claim 1, wherein said millimeter ground plane has an elongated third cavity defining a bottom portion of a transmitter waveguide bandpass filter and an elongated fourth cavity defining a bottom portion of a receiver waveguide bandpass filter, said transceiver further comprising an upper filter housing attached to said millimeter ground plane, the upper filter housing having a pair of elongated cavities defined therein aligned with said third and forth cavities, respectively, in order to define said transmitter and receiver waveguide bandpass filters, the upper filter housing having a transmitter input port and a transmitter output port defined therein in communication with said transmitter waveguide band pass filter and having a receiver input port and a receiver output port defined therein in communication with said receiver waveguide bandpass filter.

7. The complete outdoor radio unit according to claim 6, wherein said millimeter microwave printed circuit board further comprises:

a) a third microstrip projecting into said transmitter input port for introducing an unfiltered transmitter signal into said transmitter waveguide bandpass filter;

b) a fourth microstrip projecting into said transmitter output port for receiving a filtered transmitter signal from said transmitter waveguide bandpass filter;

c) a fifth microstrip projecting into said receiver input port for introducing an unfiltered received signal into said receiver waveguide bandpass filter; and

d) a sixth microstrip projecting into said receiver input port for receiving a filtered received signal from said receiver waveguide bandpass filter.

8. The complete outdoor radio unit according to claim 7, further comprising a removable insert defining a plurality of irises, the insert being removably disposed between said millimeter ground plane and said upper filter housing for altering the bandpass frequencies of said transmitter waveguide filter and said receiver waveguide filter.

9. The complete outdoor radio unit according to claim 1, further comprising a flexible cable connecting said L-band microwave printed circuit board and said millimeter microwave printed circuit board, said flexible cable comprising a plurality of coplanar, flat, thin film strip conductors embedded in polyimide.

10. The complete outdoor radio unit according to claim 9, wherein the plurality of conductors includes:

a) a plurality of direct current conductors for carrying direct current voltages and control signals; and

b) a plurality of high frequency conductors for carrying intermediate frequencies at microwave wavelengths, each said high frequency conductor having a center conductor and a pair of wide ground plane conductors, the pair of ground plane conductors being on opposite sides of said center conductor, respectively.

11. The complete outdoor radio unit according to claim 1, wherein said power supply printed circuit board has a DC—

DC converter mounted thereon, said DC—

DC converter having a base plate and having a plurality of mounting pins for attachment of said DC—

DC converter to said power supply printed circuit board, the base plate and the mounting pins extending to the same side of said DC—

DC converter so that said base plate is connected to said heat sink by a thermally conductive path.

12. The complete outdoor radio unit according to claim 1, wherein said transceiver has a frequency synthesizer circuit for producing a local oscillator signal, the frequency synthesizer circuit comprising:

a) a phase locked loop frequency synthesizer integrated circuit having a parallel data bus adapted for producing a plurality of frequencies at predetermined time intervals in response to a microprocessor control signal;

b) a low pass filter electrically connected to the output of said frequency synthesizer integrated circuit;

c) a voltage controlled oscillator electrically connected to said low pass filter and producing an output signal; and

d) a feedback loop connecting the output signal of said voltage controlled oscillator to said frequency synthesizer integrated circuit; and

e) wherein said frequency synthesizer integrated circuit is hardwired to operate at a single frequency, the parallel data bus receiving binary voltage inputs so that said frequency synthesizer produces a local oscillator signal at a fixed microwave frequency.

13. The complete outdoor radio unit according to claim 12, wherein said frequency synthesizer circuit further comprises a transistor configured as a constant current source connected to a power supply pin on said voltage controlled oscillator for reducing phase noise.

14. The complete outdoor radio unit according to claim 1, further comprising an edge coupled bandpass filter in said transmitter.

15. The complete outdoor radio unit according to claim 14, wherein said edge coupled bandpass filter comprises:

a) a flat board made from a dielectric material;

b) a plurality of flat, conductive strips deposited on said flat board, the conductive strips having a predetermined shape and spacing presenting distributed inductive, capacitive and resistive effects to an electronic signal inserted into the filter; and

c) a flat, planar, electrically conductive lid disposed above said board and said conductive strips, being spaced apart from said board by a predetermined distance.

16. The complete outdoor radio unit according to claim 15, wherein said plurality of conductive strips is shaped, spaced and configured as a bandpass filter at frequencies greater than or equal to 20 GHz.

17. The complete outdoor radio unit according to claim 15, wherein said plurality of conductive strips is shaped, spaced and configured as a five pole bandpass filter.

18. The complete outdoor radio unit according to claim 15, wherein said lid is spaced apart from said conductive strips by between about 50 to 60 mils.

19. The complete outdoor radio unit according to claim 1, further comprising:

a) an antenna horn;

b) a first waveguide connecting said millimeter microwave printed circuit board with said antenna horn, the first waveguide coupling a transmitter signal from said millimeter microwave printed circuit board to said antenna horn without a coaxial feed line; and

c) a second waveguide connecting said millimeter microwave printed circuit board with said antenna horn, the second waveguide coupling a received signal from said antenna horn to said millimeter microwave printed circuit board without a coaxial feed line.

20. The complete outdoor radio unit according to claim 1, further comprising a transmitter waveguide bandpass filter integral with said millimeter ground plane and a receiver waveguide bandpass filter integral with said millimeter ground plane, said transceiver further comprising a removable insert disposed in said waveguide filters for adjusting the band of frequencies passed by said filters.