CA2025758C - Single-block filter for antenna duplexing and antenna-switched diversity - Google Patents
Single-block filter for antenna duplexing and antenna-switched diversityInfo
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- CA2025758C CA2025758C CA002025758A CA2025758A CA2025758C CA 2025758 C CA2025758 C CA 2025758C CA 002025758 A CA002025758 A CA 002025758A CA 2025758 A CA2025758 A CA 2025758A CA 2025758 C CA2025758 C CA 2025758C
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Abstract
SINGLE-BLOCK FILTER FOR ANTENNA
DUPLEXING AND ANTENNA-SWITCHED DIVERSITY
Abstract of the Disclosure A single-block ceramic filter (102) is coupled to two antennas (142 and 144) for providing both antenna duplexing and antenna-switched diversity in a duplex radio transceiver (100). One antenna (142) is coupled by the filter (102) to a transmitter (132), and both antennas (142 and 144) are switchably coupled by the filter (102) to a receiver (130) by diversity control circuitry (101) in response to a diversity control signal (137). A
microcomputer (134) in the transceiver (100) is coupled to the receiver (130) for monitoring the received signal strength (135). When the received signal strength (135) drops in level indicating that the signal being received on one of the antennas (142 or 144) has become degraded due to fading or other interference, the microcomputer (134) changes the binary state of the diversity control signal (137) for switching the receiver (130) to the other one of the antennas (142 or 144).
DUPLEXING AND ANTENNA-SWITCHED DIVERSITY
Abstract of the Disclosure A single-block ceramic filter (102) is coupled to two antennas (142 and 144) for providing both antenna duplexing and antenna-switched diversity in a duplex radio transceiver (100). One antenna (142) is coupled by the filter (102) to a transmitter (132), and both antennas (142 and 144) are switchably coupled by the filter (102) to a receiver (130) by diversity control circuitry (101) in response to a diversity control signal (137). A
microcomputer (134) in the transceiver (100) is coupled to the receiver (130) for monitoring the received signal strength (135). When the received signal strength (135) drops in level indicating that the signal being received on one of the antennas (142 or 144) has become degraded due to fading or other interference, the microcomputer (134) changes the binary state of the diversity control signal (137) for switching the receiver (130) to the other one of the antennas (142 or 144).
Description
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.~ . ., -., ,:, ',,' :' , ~..,,:., SINGLE-BLOCK FILTER FOR ANT~NNA
DUPLEXING AND ANTENNA-SWITCHED DIVERSITY
' Back~round of the Invention The present inventiQn relates generally to radio frequency (RF) signal filters, and more particularly to a single-block filter for antenna duplexing and antenna-switched diversity in duplex radio transceivers.
A prior art single-block ceramie filter for antenna duplexing is shown and described in U.S. Patent Number 4,742,562. However, such prior art single-block ceramic filter does not accommodate antenna-switched diversity.
In the past, antenna-swi~ched diversity has been used -~
to minimize the effects of signal fading in mobile radio ~-communications systems, a problem which is aggravated in cellular teiephon~ systems due to operating frequencies ~, 25 above 80~ MHz. According to a prior antenna-switched diversity schema, a receiver i5 switched between a first ;:
antenna and a second antenna in response to detection of degradation in the received signal. This has been `
accomplished in prior art cellular telephones by utilizing a transmit filter and two separate receive filters and ~`
. switching the input of the cellular telephone receive~
between tha two receive filters, or by using a transmit ,~ filter and a receiv@ filter and switching the input of the I -receive filter between the two antennas. However, in both ,1 #
2~257~8 of the foregoing instances two s~parate fil~ers are required.
O~ ts of the ln~fen~iQn Accordingly, it is an objec~ of the present invention to provide a single-b!ock filter that is capable of both antenna duplexing and antenna-switched diversity in a duplex radio transceiver.
It is another objec~ of the present invention to ;~ provide a single-block filter having electrodes extending at ;~l least partially into corresponding resonators for coupling a transmitter and receiver of a radio transceiver to first anld second antennas.
It is further object of the present invention to provide a unique coupling electrode having a flat portion .-extending at least partially into corresponding resonators 3~ of single-block filters for couplin~ signals thereto.
Bri~f Description of the Drawinqs sl Fig. 1 illustrates a duplex radio transceiver including two antennas coupled to a single-block filter shown in ~ -perspsctive and embodying the present invention.
Fig. 2 is a perspective view of another single-block filter embodying the present invention.
Fig. 3 is a perspective view of the coupling device used in ths single-block filter in Figure 2. ~ i Fig. 4 is a flow chart of the process used by the microcomputer in Figure 1 for selecting between the two antennas coupled to the duplex radio transceiver.
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Fig. 5 is a top view of yet another sin~ls-block filter embodying the present invention, which has two antenna electrodes. I;
Fig. 6 is a top view of yet a further singl~-block .~ 5 filter embodying the present invention, which has two ! antenna electrodes.
~ , -~, 10 Referring to Figure 1, there is illustrated a duplex radio transceiver 100 including two antennas 142 and 144 !j, coupled to a single-block filter 102 shown in perspective and embodying the present invention for providing both antenna duplexing and antenna-switched diversity. Duplex radio transceiver 100 also includes receiver 130 coupled to .
speaker 131, transmitter 132 coupled to microphone 133, diversity control circuitry 101 coupled to antenna 144, and ''t microcomputer 134 coupled to receiver 130, transmitter 132 and diversity control circuitry 101 for controliing the operation thereof. Blocks 130, 131, 132, 133 and 134 of -transceiver 100 may be componen~s of any commercially available duplex radio transceiver. In the preferred -~
embodiment, transceiver 110 is the transceiver shown and described in Motorola instruction manuai number 68P81070E40, entitled "DYNATAC Cellular Mobile Telephone," published by and available from Motorola C ~ E -Parts, 1313 East Algonquin Road, Schaumburg, Illinois 60196.
According to the present invention, single-block filter 102 is coupled to antennas 142 and 144 for providing ~ -both antenna duplexing and antenna-switched diversity.
Antenna 142 is coupled by filter 102 to transmitter 132, and antellnas 142 and 144 are switchably coupled by filter 102 to receiver 130 by diversity control circuitry 101 in ;
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/ - 4 - CE00142R ~ ~ -'~!''` response to diversity control signal 137. Microcomputer 134 is coupled to receiver 130 ~or monitoring the received si~nal strength indication (RSSI~ signal 135. Wh~n the RSSI signal 135 drops in lav~l indicating that the signal 5 being received on one of the antennas 142 or 144 has ~, become degraded due to fading or other interference, '3`, microcomputer 134 chang~s the binary state o~ diversity ~i control si~nal 137 for switching receiver 130 to the other one o~ antennas 142 or 144.
.. 10 Diversity control circuitry 101 includes pin diodes 152 and 162 which are switched in response to di~ersity control signal 137 for switching receiv&r 130 between antennas 142 and 144. When antenna 144 is selected, pin , diode 152 is switched off and pin diode 162 is switched on to couple pad 118 of filter 102 to RF signal ground.
Atternatively, when antenna 142 is selected, pin diode 162 ~ P~
is switched off and pin diode 152 is switched on to couple i~ pad 117 of filter 102 to RF signal ground. Pin diodes 15 and 162 are switched on and off in response to the binary state of diversity control si~nal 137.
When diversity control signal 137 has a binary one state, the output of inverter 136 has a binary zero state (low voltage) and the output of inverter 138 has a binary ,,t~ one state (high voltage). The binary one state of the output of inverter 138 turns on transistor 156. When transistor -156 is on (conducting current), transistor 155 is turned on - -~
and applies a bias curren~ to pin diode 152 via resistor 151. Pin diode 152 is switched on (low impedance state) by this bias current and couples pad 117 and antenna t44 ~ `~
via capacitor 150 to RF signal ground. Pad 117 is j preferably coupled by a coaxial cable or alternatively a transmission line to capacitor 150 and antenna 144. It is also preferable that capacitor 150 and pin dioda 152 be located as çlose to the end A1 o~ such coaxial cable as -;
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practical. At the same time, the binary zero state of the `. output of inverter 136 turns off transistors 166 and 165, keeping pin diode 162 off ~high impedance state). Inductor 163 and capacitor 164 are coupled in parallel with pin diode 162 for resonating out parasitics due to pin diode i-~
162 to achieve better open and short circuit conditions.
Conversely, when diversity control signal 137 has a ~5 binary zero state, the output of inverter 136 has a binary ~ --~ one state (high voltage~ and the output of invortar 138 has .~ 10 a binary zero state (low voltage). The binary one state of ths output of inverter 136 turns on transistor 166. When transistor 166 is on (conducting current), transistor 165 is , turned on and applies a bias current to pin diode 162 via ;. `
'! resistor 161. Pin diode 162 is switched on (low impedance ~, 15 state) by this bias current and couples pad 118 via -I capacitor 160 to RF signal ground. Pad 118 is preferably coupled by a coaxial cable or alternatively a transmission -line to capacitor 160. It is also preferable that capacitor 160 and pin diode 162 be located as close to the end G of ~.
such coaxial cable as practical. At the same time, the binary zero state of the output of inverter 13B turns off ;~ transistors 156 and 155, keeping pin diode 152 off (high impedance state). Inductor 153 and capacitor 154 are ~, coupled in parallel with pin diode 152 for resonating out parasitics due to pin diode 152 to achieve better open and -~
short oircuit conditions. ~ -Filter 102 in Figure 1 is a dielectric block filter preferably comprised of a high-dielectric low-loss ceramic. Filter 102 may also be partially enclosed in a housing, such as housing 280 shown in Figure 2, which housing may be attached by soldering or other means ~ ~ `
producing a modular filter component. Filter 102 includes ;-transmission line resonators formed by elongated holes 103-113 extending from the top surface to the bottom , , ., .
2~2~7~8 `~ surface thereof. Holes 103-113 have a substantially rectangular cross section with rounded corners and parallel elon~ated sides. The boffom and sides of filter 102 and ;~ internal sur~aces of holes 103-113 are covered with . 5 conductive material over substantially their entire surfaces. The top surface of filter 102 is covered by a strip of conductive material near the periphery thereof which substantially surrounds holas 103-113. Also -~ disposed on the top surface are pads for each hole 103-113, pad 120 coupled by a coaxial cable ( at end T) to ,i transmitter 132, pad 116 coupied by a coaxial cable ~ at l end R) to receiver 130, pad 119 coupled by a coaxial cable ( ~, at end A2) to antenna 142, pad 117 coupled by a coaxial cable ( at end A1) to antenna 144 and capacitor 150, and pad 118 coupled by a coaxial cable ( at end G) to capacitor 160. The pads for each hole 103-113 and pads 116-120 are likewise comprised of conductive material covering the top -surface of filter 102. The pads for holes 103-113 may ;i~ have varying shapes for capacitively intercoupling with one --another and coupling to the surrounding conductive material at the sides o~ filter 102. Each of the holQs 103-113 functions essentially as a foreshortened transmission line resonator. In the preferred embodiment, the conductive material covering the surfaces of filter 102 is plated thereon.
When pad 117 is coupled to RF si~nal ground and pad ~`~ 118 is not grounded, filter 102 functions as a duplexer coupling receiver 130 and transmitter 132 to antenna 142.
Conversely, when pad 118 is coupled to RF signal ground, receiver 130 is coupled via pad 117 to antenna 144, grounded pad 118 isolates receiver from antenna 142, and ,'3 transmitter 132 is coupled to antenna 142. The amount of isolation provided by grounding pad 118 can be varied by increasing or decreasing the capacitive coupling between ,,~
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pad 118 and the pad for hole 108, by decreasing or ~ -ij increasing, respectively, the gap between pad 118 and the pad for hol~ 108, by varying the size of the opposing edges of pads 108 and 118, or by any other suitable means. The ;
amount of couplin~ provided by pad 117 can likewise be -~ varied with respoct to ~he pad for hole 107. In other embodiments, pad 118 may be directly ccnnected to hole 108 or may be a portion of the pad for hole lG8.
3 Referring next to Figuro 4, there is illustrated a flow m chart of the process usad by the microcomputer 134 in Figure 1 for selecting between the antennas 142 and 144.
Entering at START block 402, the process proceeds to block 404, where the guard time flag is checked. If ~he guard time flag has a binary one state, YES branch is taken to block 408. At block 408, a check is made to determine if ; ~;
the four millisecond timar (4 MS) has timed out. If not, NO
branch is taken to RETURN block 420 ~o return to other J tasks. If the four mitlisecond timer (4 MS) has tirned out, ~;
YES branch is taken from block 408 to block 409 where the guard time flag is reset to a binary zero state. Thereafter, ~ -program control proceeds to block 410 as described hereinbelow.
Returning to block 404, if the guard time flag has a binary zero state, NO branch is taken to block 406, where a check is made to determine if the ten millisecond timer ~
(10 MS) has timed out. If not, NO branch is taken to RETURN - - ~ ~;
block 420 to return to other tasks. If the 10 MS timer has timed out, YES branch is taken from block 406 to block 410 -~
where an RSSI sample is taken. Block 410 is also reached from blocks 408 and 409 after the 4 MS timer has timad - -~ -out. Microcomputer 134 includes an analog-to-digital ;~
converter for taking a di~itized sample of the RSSI signal 135. Next~ at block 412, a check is made to determine if ~ ~.
2~2~7~8 - -the RSSI sample is 6 dB less than ~he average RSSI. The ~` average RSSI is a running averago taken by microcomputor 134 over the last fifty RSSI samples. If the RSSI sample is ;'i not 6 dB less than the average RSSI, NO branch is taken 5 from block 412 to block 414 wh~re the average RSSI is updated using the current RSSI sample, andl the 10 MS timer is restarted for another ten millisacond time interval.
Thereafter, program contrel returns to other tasks at ,t RETURN block 420.
Returning to block 412, if the RSSI sample is 6 dB
less than the average RSSI, YES branch is taken to block i' 416 where the binary state of the diversity control signal 137 is changed to switch between antennas 142 and 144. ~ -Next, at block 418 the guard time flag is set to a binary one 15 statc, and the 4 MS timer is restarted for a four millisecond time interval. The guard time flag is set in order to sample the RSSI signal 135 four milliseconds - after switching between antennas 142 and 144. As a --~
result, RSSI signal 135 will be sampled again after four -20 milliseconds rather than ten milliseconds. The sampling ~ n~
interval is reduced in order to be sure that the antenna 142 ~ -or 144 being switched to is rec~iving an adequate RF
signal. If both antennas 142 and 144 are receiving poor RF
signals, receiver 130 will be switched from one antenna to 25 the other every four milliseconds. Thereafter, program control returns tc other tasks at RETURN block 420.
Referring to Figure 2, there is illustrated another filter 202 embodying the present invention. Instead of ~-usin~ pads for coupling signals theretoi filter 202 includes 3û coupling electrodes 216, 217, 218, 219, and 220, which `~ extend at least partially into corresponding holes 203, 207, 208, 209, and 213, respectively. Electrodes 216-220 are positioned and retained in holes 203, 207, 208, 209, and 213 by means of dielectric plugs 226-230, respectively.
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Plugs 226-230 may be comprised of any suitable - :.
. dielectric, such as, for ~xample, ceramic or plastic. Plugs 226-230 may be retain~d in holes 203, 207, 208, 209, and ~
~' 213 by means of a press fit, glue, or other suitable means. ;~.-,~ 5 Plugs 226-230 may also be loosely fitted in holes 203, 207, 208, 209, and 213 and retained thereirl by a housing 280 which extends over plugs 226-230 and has holes ..
therein allowing electrodes 216-220 to protrude therefrom. Once housing 2~0 is attached by soldering or ~ - .
other suitable means, filter 202 may be mounted on a ~ ~-printed circuit board (not shown3 as a modular filter component. . -P~eferring to Figure 3, there is illustrated a unique coupling el~ctrode 216 having a flat portion 316, 317 extending at least partially into a corresponding hole 203 of filter 202 for coupling signals thereto. Electrode 216 -inserts into plug 326, which includes a top portion 226 and ~ r ~-a rectangular shaped hold 318 for accepting flat portion 316, 317 of electrode 2t6. Electrode 216 may have a shape 2û and size that varies for varying the amount of coupling to ~ -~
the resonator provided by hole 203. For example, eleotrode 216 may have a rectangular shape 317 or triangular shape 316. In other embodiments, electrode 216 may simply be a pin. Coupling slectrodes 217, 218, 219, and 220 and -:
2~ correspondin~ plugs 227, 228, 229 and 230 may also be implemented as shown in Figure 3.
Referring to Figure 5, there is illus~rated a top view of yet another single-block filter 500 embodyin~ the `~
present invention, which has two antenna pads 524 and 526. The embodiment in Figure 5 makes better use of the isolation characteristics of filter 500. Pad 524 is a strip ; of conductive material located between holes 508 and 509, ~ ~
and pad 526 is also a strip of conductive material located ~ ~ -between holas 509 and 510. Pad 524 extends from the -;l ::-, ~.:. .
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, . opposite side of filter 500 as does pad 526. The width, length and positioning of pads 524 and 526 may be varied to vary the coupling to corresponding holes 508, 509 and 509, 510, respectiv~ly. Pad 526 couples antenna terminal .` 5 A2 to resonators 509 and 510. Switch 522 is responsive to -~
diversity control signal 137 for switching pad 524 to either antanna terminal A1 or antenna terrninal A2. Switch 522 may be implemented with one or more conventional reed relays or with pin diodes and transmission line circuitry. The pads for holes 503-513 of filter 500 have ;~
.~ varylng shapes for capacitively intercoupling with one another and coupling to the sùrrounding conductive material at the sides of the block.
Referring to Figure 6, there is illustrated a top view of yet a further singla-block filter 600 embodying the present invention, which has two antenna pads 624 and 626. The embodiment in Figure 6 makes better use of tha isolation characteristics of filter 600. Pad 624 is a strip ~ ~ `
;~ of conductive material located between holes 608 and 609, : `,1 and pad 626 is also a strip of conductive material located between holes 609 and 610. Pad 624 extends from the same side of filter 600 as does pad 626. The width, length and positioning of pads 624 and 626 may be varied to vary the coupling to corresponding holes 608, 609 and 609, 610, respectively. Pad 626 couples antenna terminal A2 to resonators 609 and 610. Switch 622 is responsive to ~j diversity control signal 137 for switching pad 624 to either antenna terminal A1 or antenna terminal A2. Switch 622 may be implemented with one or more conventional ~', 30 reed relays or with pin diodes and transmission line circuitry. The pads for holes 603-613 of filter 600 have varying shapes for capacitively intercoupling with one another and coupling to the surrounding conductive .' material at the sides of the block.
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!~ In summary, a unique single-block fi!ter has been ~`~i` described which is capable of providing both antenna duplexing and antenna-switched diversity in a duplex radio - .
transceiver. The unique single-block filter rnay include coupling electrodes and a housing for providing a modular ;~
filtsr component. Moreover, the single-block filter may --include unique coupling electrodes having a flat portion ~, extending at least partially into corresponding resonators thereof for coupling signals there~o. The unique single-block filter and unique coupling electrodes of the present s. invention may be advantageously utilized in applications ~ -where RF filtering, antenna duplexing and/or antenna diversity is desired. ;
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.~ . ., -., ,:, ',,' :' , ~..,,:., SINGLE-BLOCK FILTER FOR ANT~NNA
DUPLEXING AND ANTENNA-SWITCHED DIVERSITY
' Back~round of the Invention The present inventiQn relates generally to radio frequency (RF) signal filters, and more particularly to a single-block filter for antenna duplexing and antenna-switched diversity in duplex radio transceivers.
A prior art single-block ceramie filter for antenna duplexing is shown and described in U.S. Patent Number 4,742,562. However, such prior art single-block ceramic filter does not accommodate antenna-switched diversity.
In the past, antenna-swi~ched diversity has been used -~
to minimize the effects of signal fading in mobile radio ~-communications systems, a problem which is aggravated in cellular teiephon~ systems due to operating frequencies ~, 25 above 80~ MHz. According to a prior antenna-switched diversity schema, a receiver i5 switched between a first ;:
antenna and a second antenna in response to detection of degradation in the received signal. This has been `
accomplished in prior art cellular telephones by utilizing a transmit filter and two separate receive filters and ~`
. switching the input of the cellular telephone receive~
between tha two receive filters, or by using a transmit ,~ filter and a receiv@ filter and switching the input of the I -receive filter between the two antennas. However, in both ,1 #
2~257~8 of the foregoing instances two s~parate fil~ers are required.
O~ ts of the ln~fen~iQn Accordingly, it is an objec~ of the present invention to provide a single-b!ock filter that is capable of both antenna duplexing and antenna-switched diversity in a duplex radio transceiver.
It is another objec~ of the present invention to ;~ provide a single-block filter having electrodes extending at ;~l least partially into corresponding resonators for coupling a transmitter and receiver of a radio transceiver to first anld second antennas.
It is further object of the present invention to provide a unique coupling electrode having a flat portion .-extending at least partially into corresponding resonators 3~ of single-block filters for couplin~ signals thereto.
Bri~f Description of the Drawinqs sl Fig. 1 illustrates a duplex radio transceiver including two antennas coupled to a single-block filter shown in ~ -perspsctive and embodying the present invention.
Fig. 2 is a perspective view of another single-block filter embodying the present invention.
Fig. 3 is a perspective view of the coupling device used in ths single-block filter in Figure 2. ~ i Fig. 4 is a flow chart of the process used by the microcomputer in Figure 1 for selecting between the two antennas coupled to the duplex radio transceiver.
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Fig. 5 is a top view of yet another sin~ls-block filter embodying the present invention, which has two antenna electrodes. I;
Fig. 6 is a top view of yet a further singl~-block .~ 5 filter embodying the present invention, which has two ! antenna electrodes.
~ , -~, 10 Referring to Figure 1, there is illustrated a duplex radio transceiver 100 including two antennas 142 and 144 !j, coupled to a single-block filter 102 shown in perspective and embodying the present invention for providing both antenna duplexing and antenna-switched diversity. Duplex radio transceiver 100 also includes receiver 130 coupled to .
speaker 131, transmitter 132 coupled to microphone 133, diversity control circuitry 101 coupled to antenna 144, and ''t microcomputer 134 coupled to receiver 130, transmitter 132 and diversity control circuitry 101 for controliing the operation thereof. Blocks 130, 131, 132, 133 and 134 of -transceiver 100 may be componen~s of any commercially available duplex radio transceiver. In the preferred -~
embodiment, transceiver 110 is the transceiver shown and described in Motorola instruction manuai number 68P81070E40, entitled "DYNATAC Cellular Mobile Telephone," published by and available from Motorola C ~ E -Parts, 1313 East Algonquin Road, Schaumburg, Illinois 60196.
According to the present invention, single-block filter 102 is coupled to antennas 142 and 144 for providing ~ -both antenna duplexing and antenna-switched diversity.
Antenna 142 is coupled by filter 102 to transmitter 132, and antellnas 142 and 144 are switchably coupled by filter 102 to receiver 130 by diversity control circuitry 101 in ;
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/ - 4 - CE00142R ~ ~ -'~!''` response to diversity control signal 137. Microcomputer 134 is coupled to receiver 130 ~or monitoring the received si~nal strength indication (RSSI~ signal 135. Wh~n the RSSI signal 135 drops in lav~l indicating that the signal 5 being received on one of the antennas 142 or 144 has ~, become degraded due to fading or other interference, '3`, microcomputer 134 chang~s the binary state o~ diversity ~i control si~nal 137 for switching receiver 130 to the other one o~ antennas 142 or 144.
.. 10 Diversity control circuitry 101 includes pin diodes 152 and 162 which are switched in response to di~ersity control signal 137 for switching receiv&r 130 between antennas 142 and 144. When antenna 144 is selected, pin , diode 152 is switched off and pin diode 162 is switched on to couple pad 118 of filter 102 to RF signal ground.
Atternatively, when antenna 142 is selected, pin diode 162 ~ P~
is switched off and pin diode 152 is switched on to couple i~ pad 117 of filter 102 to RF signal ground. Pin diodes 15 and 162 are switched on and off in response to the binary state of diversity control si~nal 137.
When diversity control signal 137 has a binary one state, the output of inverter 136 has a binary zero state (low voltage) and the output of inverter 138 has a binary ,,t~ one state (high voltage). The binary one state of the output of inverter 138 turns on transistor 156. When transistor -156 is on (conducting current), transistor 155 is turned on - -~
and applies a bias curren~ to pin diode 152 via resistor 151. Pin diode 152 is switched on (low impedance state) by this bias current and couples pad 117 and antenna t44 ~ `~
via capacitor 150 to RF signal ground. Pad 117 is j preferably coupled by a coaxial cable or alternatively a transmission line to capacitor 150 and antenna 144. It is also preferable that capacitor 150 and pin dioda 152 be located as çlose to the end A1 o~ such coaxial cable as -;
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practical. At the same time, the binary zero state of the `. output of inverter 136 turns off transistors 166 and 165, keeping pin diode 162 off ~high impedance state). Inductor 163 and capacitor 164 are coupled in parallel with pin diode 162 for resonating out parasitics due to pin diode i-~
162 to achieve better open and short circuit conditions.
Conversely, when diversity control signal 137 has a ~5 binary zero state, the output of inverter 136 has a binary ~ --~ one state (high voltage~ and the output of invortar 138 has .~ 10 a binary zero state (low voltage). The binary one state of ths output of inverter 136 turns on transistor 166. When transistor 166 is on (conducting current), transistor 165 is , turned on and applies a bias current to pin diode 162 via ;. `
'! resistor 161. Pin diode 162 is switched on (low impedance ~, 15 state) by this bias current and couples pad 118 via -I capacitor 160 to RF signal ground. Pad 118 is preferably coupled by a coaxial cable or alternatively a transmission -line to capacitor 160. It is also preferable that capacitor 160 and pin diode 162 be located as close to the end G of ~.
such coaxial cable as practical. At the same time, the binary zero state of the output of inverter 13B turns off ;~ transistors 156 and 155, keeping pin diode 152 off (high impedance state). Inductor 153 and capacitor 154 are ~, coupled in parallel with pin diode 152 for resonating out parasitics due to pin diode 152 to achieve better open and -~
short oircuit conditions. ~ -Filter 102 in Figure 1 is a dielectric block filter preferably comprised of a high-dielectric low-loss ceramic. Filter 102 may also be partially enclosed in a housing, such as housing 280 shown in Figure 2, which housing may be attached by soldering or other means ~ ~ `
producing a modular filter component. Filter 102 includes ;-transmission line resonators formed by elongated holes 103-113 extending from the top surface to the bottom , , ., .
2~2~7~8 `~ surface thereof. Holes 103-113 have a substantially rectangular cross section with rounded corners and parallel elon~ated sides. The boffom and sides of filter 102 and ;~ internal sur~aces of holes 103-113 are covered with . 5 conductive material over substantially their entire surfaces. The top surface of filter 102 is covered by a strip of conductive material near the periphery thereof which substantially surrounds holas 103-113. Also -~ disposed on the top surface are pads for each hole 103-113, pad 120 coupled by a coaxial cable ( at end T) to ,i transmitter 132, pad 116 coupied by a coaxial cable ~ at l end R) to receiver 130, pad 119 coupled by a coaxial cable ( ~, at end A2) to antenna 142, pad 117 coupled by a coaxial cable ( at end A1) to antenna 144 and capacitor 150, and pad 118 coupled by a coaxial cable ( at end G) to capacitor 160. The pads for each hole 103-113 and pads 116-120 are likewise comprised of conductive material covering the top -surface of filter 102. The pads for holes 103-113 may ;i~ have varying shapes for capacitively intercoupling with one --another and coupling to the surrounding conductive material at the sides o~ filter 102. Each of the holQs 103-113 functions essentially as a foreshortened transmission line resonator. In the preferred embodiment, the conductive material covering the surfaces of filter 102 is plated thereon.
When pad 117 is coupled to RF si~nal ground and pad ~`~ 118 is not grounded, filter 102 functions as a duplexer coupling receiver 130 and transmitter 132 to antenna 142.
Conversely, when pad 118 is coupled to RF signal ground, receiver 130 is coupled via pad 117 to antenna 144, grounded pad 118 isolates receiver from antenna 142, and ,'3 transmitter 132 is coupled to antenna 142. The amount of isolation provided by grounding pad 118 can be varied by increasing or decreasing the capacitive coupling between ,,~
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pad 118 and the pad for hole 108, by decreasing or ~ -ij increasing, respectively, the gap between pad 118 and the pad for hol~ 108, by varying the size of the opposing edges of pads 108 and 118, or by any other suitable means. The ;
amount of couplin~ provided by pad 117 can likewise be -~ varied with respoct to ~he pad for hole 107. In other embodiments, pad 118 may be directly ccnnected to hole 108 or may be a portion of the pad for hole lG8.
3 Referring next to Figuro 4, there is illustrated a flow m chart of the process usad by the microcomputer 134 in Figure 1 for selecting between the antennas 142 and 144.
Entering at START block 402, the process proceeds to block 404, where the guard time flag is checked. If ~he guard time flag has a binary one state, YES branch is taken to block 408. At block 408, a check is made to determine if ; ~;
the four millisecond timar (4 MS) has timed out. If not, NO
branch is taken to RETURN block 420 ~o return to other J tasks. If the four mitlisecond timer (4 MS) has tirned out, ~;
YES branch is taken from block 408 to block 409 where the guard time flag is reset to a binary zero state. Thereafter, ~ -program control proceeds to block 410 as described hereinbelow.
Returning to block 404, if the guard time flag has a binary zero state, NO branch is taken to block 406, where a check is made to determine if the ten millisecond timer ~
(10 MS) has timed out. If not, NO branch is taken to RETURN - - ~ ~;
block 420 to return to other tasks. If the 10 MS timer has timed out, YES branch is taken from block 406 to block 410 -~
where an RSSI sample is taken. Block 410 is also reached from blocks 408 and 409 after the 4 MS timer has timad - -~ -out. Microcomputer 134 includes an analog-to-digital ;~
converter for taking a di~itized sample of the RSSI signal 135. Next~ at block 412, a check is made to determine if ~ ~.
2~2~7~8 - -the RSSI sample is 6 dB less than ~he average RSSI. The ~` average RSSI is a running averago taken by microcomputor 134 over the last fifty RSSI samples. If the RSSI sample is ;'i not 6 dB less than the average RSSI, NO branch is taken 5 from block 412 to block 414 wh~re the average RSSI is updated using the current RSSI sample, andl the 10 MS timer is restarted for another ten millisacond time interval.
Thereafter, program contrel returns to other tasks at ,t RETURN block 420.
Returning to block 412, if the RSSI sample is 6 dB
less than the average RSSI, YES branch is taken to block i' 416 where the binary state of the diversity control signal 137 is changed to switch between antennas 142 and 144. ~ -Next, at block 418 the guard time flag is set to a binary one 15 statc, and the 4 MS timer is restarted for a four millisecond time interval. The guard time flag is set in order to sample the RSSI signal 135 four milliseconds - after switching between antennas 142 and 144. As a --~
result, RSSI signal 135 will be sampled again after four -20 milliseconds rather than ten milliseconds. The sampling ~ n~
interval is reduced in order to be sure that the antenna 142 ~ -or 144 being switched to is rec~iving an adequate RF
signal. If both antennas 142 and 144 are receiving poor RF
signals, receiver 130 will be switched from one antenna to 25 the other every four milliseconds. Thereafter, program control returns tc other tasks at RETURN block 420.
Referring to Figure 2, there is illustrated another filter 202 embodying the present invention. Instead of ~-usin~ pads for coupling signals theretoi filter 202 includes 3û coupling electrodes 216, 217, 218, 219, and 220, which `~ extend at least partially into corresponding holes 203, 207, 208, 209, and 213, respectively. Electrodes 216-220 are positioned and retained in holes 203, 207, 208, 209, and 213 by means of dielectric plugs 226-230, respectively.
~, ., .
- :
.
:
. .
2~2~7~
- 9 - CE00142R ~ ~
, . -.
Plugs 226-230 may be comprised of any suitable - :.
. dielectric, such as, for ~xample, ceramic or plastic. Plugs 226-230 may be retain~d in holes 203, 207, 208, 209, and ~
~' 213 by means of a press fit, glue, or other suitable means. ;~.-,~ 5 Plugs 226-230 may also be loosely fitted in holes 203, 207, 208, 209, and 213 and retained thereirl by a housing 280 which extends over plugs 226-230 and has holes ..
therein allowing electrodes 216-220 to protrude therefrom. Once housing 2~0 is attached by soldering or ~ - .
other suitable means, filter 202 may be mounted on a ~ ~-printed circuit board (not shown3 as a modular filter component. . -P~eferring to Figure 3, there is illustrated a unique coupling el~ctrode 216 having a flat portion 316, 317 extending at least partially into a corresponding hole 203 of filter 202 for coupling signals thereto. Electrode 216 -inserts into plug 326, which includes a top portion 226 and ~ r ~-a rectangular shaped hold 318 for accepting flat portion 316, 317 of electrode 2t6. Electrode 216 may have a shape 2û and size that varies for varying the amount of coupling to ~ -~
the resonator provided by hole 203. For example, eleotrode 216 may have a rectangular shape 317 or triangular shape 316. In other embodiments, electrode 216 may simply be a pin. Coupling slectrodes 217, 218, 219, and 220 and -:
2~ correspondin~ plugs 227, 228, 229 and 230 may also be implemented as shown in Figure 3.
Referring to Figure 5, there is illus~rated a top view of yet another single-block filter 500 embodyin~ the `~
present invention, which has two antenna pads 524 and 526. The embodiment in Figure 5 makes better use of the isolation characteristics of filter 500. Pad 524 is a strip ; of conductive material located between holes 508 and 509, ~ ~
and pad 526 is also a strip of conductive material located ~ ~ -between holas 509 and 510. Pad 524 extends from the -;l ::-, ~.:. .
'~3 ~ :.
~j " "
'.:.:.: ' ' : :
2Q2~7~8 .. ~ .
~ - 10 ~ CE001 42R
, . opposite side of filter 500 as does pad 526. The width, length and positioning of pads 524 and 526 may be varied to vary the coupling to corresponding holes 508, 509 and 509, 510, respectiv~ly. Pad 526 couples antenna terminal .` 5 A2 to resonators 509 and 510. Switch 522 is responsive to -~
diversity control signal 137 for switching pad 524 to either antanna terminal A1 or antenna terrninal A2. Switch 522 may be implemented with one or more conventional reed relays or with pin diodes and transmission line circuitry. The pads for holes 503-513 of filter 500 have ;~
.~ varylng shapes for capacitively intercoupling with one another and coupling to the sùrrounding conductive material at the sides of the block.
Referring to Figure 6, there is illustrated a top view of yet a further singla-block filter 600 embodying the present invention, which has two antenna pads 624 and 626. The embodiment in Figure 6 makes better use of tha isolation characteristics of filter 600. Pad 624 is a strip ~ ~ `
;~ of conductive material located between holes 608 and 609, : `,1 and pad 626 is also a strip of conductive material located between holes 609 and 610. Pad 624 extends from the same side of filter 600 as does pad 626. The width, length and positioning of pads 624 and 626 may be varied to vary the coupling to corresponding holes 608, 609 and 609, 610, respectively. Pad 626 couples antenna terminal A2 to resonators 609 and 610. Switch 622 is responsive to ~j diversity control signal 137 for switching pad 624 to either antenna terminal A1 or antenna terminal A2. Switch 622 may be implemented with one or more conventional ~', 30 reed relays or with pin diodes and transmission line circuitry. The pads for holes 603-613 of filter 600 have varying shapes for capacitively intercoupling with one another and coupling to the surrounding conductive .' material at the sides of the block.
'!! ; `:-!' ' ` .
:~:
., ~, .~.; ' .
~ 20~7~8 : ; .', - 11 - CEOû142R
!~ In summary, a unique single-block fi!ter has been ~`~i` described which is capable of providing both antenna duplexing and antenna-switched diversity in a duplex radio - .
transceiver. The unique single-block filter rnay include coupling electrodes and a housing for providing a modular ;~
filtsr component. Moreover, the single-block filter may --include unique coupling electrodes having a flat portion ~, extending at least partially into corresponding resonators thereof for coupling signals there~o. The unique single-block filter and unique coupling electrodes of the present s. invention may be advantageously utilized in applications ~ -where RF filtering, antenna duplexing and/or antenna diversity is desired. ;
.!:1 ' `';~ : ~
`I ' '`,.,:
.. . .
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,. . .
,.
,,.. ,.,~ ~., .~ . . - - . .. - .. . -.
Claims (18)
1. A filter for coupling a transmitter to a first antenna and coupling a receiver to the first antenna and, in response to a control signal from a signal source, coupling the receiver to a second antenna, comprising:
a dielectric block having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;
first coupling means coupling the transmitter to said first hole;
second coupling means coupling the first antenna to said second hole;
third coupling means for coupling said third hole to signal ground in response to the control signal;
fourth couping means for coupling said fourth hole to the second antenna in response to the control signal;
and fifth coupling means for coupling said fifth hole to the receiver.
a dielectric block having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;
first coupling means coupling the transmitter to said first hole;
second coupling means coupling the first antenna to said second hole;
third coupling means for coupling said third hole to signal ground in response to the control signal;
fourth couping means for coupling said fourth hole to the second antenna in response to the control signal;
and fifth coupling means for coupling said fifth hole to the receiver.
2. The filter of claim 1, wherein said third coupling means includes switching means responsive to the control signal for switching said third hole to signal ground.
3. The filter of claim 2, wherein said switching means includes pin diode means.
4. The filter of claim 1, wherein said fourth coupling means includes switching means responsive to the control signal for switching said fourth hole between the second antenna and signal ground.
5. The filter of claim 4, wherein said switching means includes pin diode means.
6. The filter of claim 1, wherein said filter is used in a radio, said radio comprises:
a first antenna;
a second antenna;
a transmitter having an output;
a receiver having an input; and control means coupled to the transmitter and receiver and producing a control signal;
whereby said filter couples the transmitter to the first antenna and couples the receiver to the first antenna and, in response to the control signal, couples the receiver to the second antenna.
a first antenna;
a second antenna;
a transmitter having an output;
a receiver having an input; and control means coupled to the transmitter and receiver and producing a control signal;
whereby said filter couples the transmitter to the first antenna and couples the receiver to the first antenna and, in response to the control signal, couples the receiver to the second antenna.
7. The filter of claim 6, wherein said third coupling means includes switching means responsive to the control signal for switching said third hole to signal ground.
8. The filter of claim 7, wherein said switching means includes pin diode means.
9. The filter of claim 6, wherein said fourth coupling means includes switching means responsive to the control signal for switching said fourth hole between the second antenna and signal ground.
10. The filter of claim 9, wherein said switching means includes pin diode means.
11. The filter of claim 6, wherein said receiver includes means for producing an output signal having a magnitude related to the strength of signal received by said receiver, and said control means includes processing means coupled to the output signal of the receiver for producing a first binary state of the control signal when the output signal of the receiver has a magnitude at least as great as a predetermined magnitude and a second binary state of the control signal when the output signal of the receiver has a magnitude less than the predetermined magnitude.
12. The filter of claim 11, wherein said processing means samples the output of the receiver at least once every predetermined time interval and thereafter produces the first or second binary state of the control signal.
13. A filter for coupling a transmitter to a first antenna and coupling a receiver to the first antenna and, in response to a control signal from a signal source, coupling the receiver to a second antenna, comprising:
a dielectric block having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;
first coupling means having an electrode extending at least partially into said first hole for coupling said first hole to the transmitter;
second coupling means having an electrode extending at least partially into said second hole for coupling said second hole to the first antenna;
third coupling means having an electrode extending at least partially into said third hole for coupling said third hole to signal ground in response to the control signal;
fourth couping means having an electrode extending at least partially into said fourth hole for coupling said fourth hole to the second antenna in response to the control signal; and fifth coupling means having an electrode extending at least partially into said fifth hole for coupling said fifth hole to the receiver.
a dielectric block having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;
first coupling means having an electrode extending at least partially into said first hole for coupling said first hole to the transmitter;
second coupling means having an electrode extending at least partially into said second hole for coupling said second hole to the first antenna;
third coupling means having an electrode extending at least partially into said third hole for coupling said third hole to signal ground in response to the control signal;
fourth couping means having an electrode extending at least partially into said fourth hole for coupling said fourth hole to the second antenna in response to the control signal; and fifth coupling means having an electrode extending at least partially into said fifth hole for coupling said fifth hole to the receiver.
14. A filter for filtering first and second signals from first and second signal sources to produce filtered first and second signals, respectively, said filter comprising:
a dielectric block having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;
first coupling means coupling the first signal to said first hole;
second coupling means coupling the filtered first signal from said second hole;
third coupling means for coupling said third hole to signal ground;
fourth couping means for coupling the second signal to said fourth hole; and fifth coupling means for coupling the filtered second signal from said fifth hole.
a dielectric block having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;
first coupling means coupling the first signal to said first hole;
second coupling means coupling the filtered first signal from said second hole;
third coupling means for coupling said third hole to signal ground;
fourth couping means for coupling the second signal to said fourth hole; and fifth coupling means for coupling the filtered second signal from said fifth hole.
15. The filter of claim 13, wherein said filter is used in a radio, said radio comprises:
a first antenna;
a second antenna;
a transmitter having an output;
a receiver having an input; and control means coupled to the transmitter and receiver and producing a control signal;
whereby said filter couples the transmitter to the first antenna and couples the receiver to the first antenna and, in response to the control signal, couples the receiver to the second antenna.
a first antenna;
a second antenna;
a transmitter having an output;
a receiver having an input; and control means coupled to the transmitter and receiver and producing a control signal;
whereby said filter couples the transmitter to the first antenna and couples the receiver to the first antenna and, in response to the control signal, couples the receiver to the second antenna.
16. A filter for use in a radio, said radio comprising:
an antenna; and a transmitter having an output;
said filter comprising:
a dielectric block having top, bottom and side surfaces and having at least two holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said at least two holes being substantially covered with a conductive material;
first coupling means including first electrode means having a flat portion extending at least partially into one of said at least two holes for coupling said one of said at least two holes to the output of the transmitter, and first plug means comprised of a dielectric material for enclosing at least the flat portion of said first electrode means and positioning said flat portionof said first electrode means in said one of said at least two holes; and second coupling means including second electrode means having a flat portion extending at least partially into another of said at least two holes for coupling said another of said at least two holes to the antenna, and second plug means comprised of a dielectric material for enclosing at least the flat portion of said second electrode means and positioning said flat portion of saidsecond electrode means in said another of said at least two holes, whereby said filter couples the transmitter to the antenna.
an antenna; and a transmitter having an output;
said filter comprising:
a dielectric block having top, bottom and side surfaces and having at least two holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said at least two holes being substantially covered with a conductive material;
first coupling means including first electrode means having a flat portion extending at least partially into one of said at least two holes for coupling said one of said at least two holes to the output of the transmitter, and first plug means comprised of a dielectric material for enclosing at least the flat portion of said first electrode means and positioning said flat portionof said first electrode means in said one of said at least two holes; and second coupling means including second electrode means having a flat portion extending at least partially into another of said at least two holes for coupling said another of said at least two holes to the antenna, and second plug means comprised of a dielectric material for enclosing at least the flat portion of said second electrode means and positioning said flat portion of saidsecond electrode means in said another of said at least two holes, whereby said filter couples the transmitter to the antenna.
17. A filter for use in a radio, said radio comprising:
an antenna; and a receiver having an input;
said filter comprising:
a dielectric block having top, bottom and side surfaces and having at least two holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said at least two holes being substantially covered with a conductive material;
first coupling means including first electrode means having a flat portion extending at least partially into one of said at least two holes for coupling said one of said at least two holes to the input of the receiver, and first plug means comprised of a dielectric material for enclosing at least the flat portion of said first electrode means and positioning said flat portion of said first electrode means in said one of said at least two holes; and second coupling means including second electrode means having a flat portion extending at least partially into another of said at least two holes for coupling said another of said at least two holes to the antenna, and second plug means comprised of a dielectric material for enclosing at least the flat portion of said second electrode means and positioning said flat portion of saidsecond electrode means in said another of said at least two holes, whereby said filter couples the receiver to the antenna.
an antenna; and a receiver having an input;
said filter comprising:
a dielectric block having top, bottom and side surfaces and having at least two holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said at least two holes being substantially covered with a conductive material;
first coupling means including first electrode means having a flat portion extending at least partially into one of said at least two holes for coupling said one of said at least two holes to the input of the receiver, and first plug means comprised of a dielectric material for enclosing at least the flat portion of said first electrode means and positioning said flat portion of said first electrode means in said one of said at least two holes; and second coupling means including second electrode means having a flat portion extending at least partially into another of said at least two holes for coupling said another of said at least two holes to the antenna, and second plug means comprised of a dielectric material for enclosing at least the flat portion of said second electrode means and positioning said flat portion of saidsecond electrode means in said another of said at least two holes, whereby said filter couples the receiver to the antenna.
18. The filter of claim 1, wherein said filter is used in a radio, said radio comprises:
a first antenna;
a transmitter having an output; and a receiver having an input;
whereby said filter couples the transmitter to the first antenna and couples the receiver to the first antenna and, in response to a control signal, couples the receiver to a second antenna.
a first antenna;
a transmitter having an output; and a receiver having an input;
whereby said filter couples the transmitter to the first antenna and couples the receiver to the first antenna and, in response to a control signal, couples the receiver to a second antenna.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US42825389A | 1989-10-27 | 1989-10-27 | |
| US428,253 | 1989-10-27 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2025758A1 CA2025758A1 (en) | 1991-04-28 |
| CA2025758C true CA2025758C (en) | 1994-07-12 |
Family
ID=23698120
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002025758A Expired - Fee Related CA2025758C (en) | 1989-10-27 | 1990-09-19 | Single-block filter for antenna duplexing and antenna-switched diversity |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2602121B2 (en) |
| CA (1) | CA2025758C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003060408A (en) | 2001-06-05 | 2003-02-28 | Murata Mfg Co Ltd | Filter component and communication apparatus |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61179603A (en) * | 1985-02-04 | 1986-08-12 | Murata Mfg Co Ltd | Distributed constant type dielectric resonator |
| JPS6340009U (en) * | 1986-09-02 | 1988-03-15 | ||
| JPS63174402A (en) * | 1987-01-13 | 1988-07-18 | Murata Mfg Co Ltd | Dielectric filter device |
-
1990
- 1990-09-19 CA CA002025758A patent/CA2025758C/en not_active Expired - Fee Related
- 1990-10-09 JP JP2272097A patent/JP2602121B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03147401A (en) | 1991-06-24 |
| JP2602121B2 (en) | 1997-04-23 |
| CA2025758A1 (en) | 1991-04-28 |
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| EEER | Examination request | ||
| MKLA | Lapsed |