CA2001308A1 - Short range multi-channel microwave transmitter - Google Patents
Short range multi-channel microwave transmitterInfo
- Publication number
- CA2001308A1 CA2001308A1 CA002001308A CA2001308A CA2001308A1 CA 2001308 A1 CA2001308 A1 CA 2001308A1 CA 002001308 A CA002001308 A CA 002001308A CA 2001308 A CA2001308 A CA 2001308A CA 2001308 A1 CA2001308 A1 CA 2001308A1
- Authority
- CA
- Canada
- Prior art keywords
- frequency
- output
- operatively associated
- power amplifier
- microwave
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Abstract
ABSTRACT OF THE DISCLOSURE
The invention is a short range improved multi-channel microwave distribution system (MMDS) for local television retransmission. The current MMDS systems cannot produce a satisfactory noise free signal at a low enough transmission wattage to be economic. The invention by using a single microwave frequency modulator in tandem with a power amplifier operating well below the linear/nonlinear output transition point, allows retransmission of a satisfactory noise free signal at low wattage. The improved MMDS is economic in power use and cost, and has a range of about 10 km, under favorable terrain conditions up to 13 km, at 1 watt per channel, antenna output.
The invention is a short range improved multi-channel microwave distribution system (MMDS) for local television retransmission. The current MMDS systems cannot produce a satisfactory noise free signal at a low enough transmission wattage to be economic. The invention by using a single microwave frequency modulator in tandem with a power amplifier operating well below the linear/nonlinear output transition point, allows retransmission of a satisfactory noise free signal at low wattage. The improved MMDS is economic in power use and cost, and has a range of about 10 km, under favorable terrain conditions up to 13 km, at 1 watt per channel, antenna output.
Description
~,Jn~
SHORT RANGE MULTI-CHANNEI, MICROWAV~ TRANSMITTER
This invention relates to short range multi-channel microwave transmitters. Partlcularly it relates to such transmitters adapted ~or transmission of television.
` BACKGROUND OF INVENTION
. , .
There is an increasin~ demand for multi-channel television reception.
At present television broadcasts are transmitted and received in several ways.
Direct transmission, or retransmission, from a transmission tower to a television aerial, is only suitable for large urban areas. These generally use VHF
or UHF radio waves (Very High Frequency or Ultra High Frequency).
Satellite (re)transmission, generally by mlcrowave to a satellite receiving dish, or a satellite receiver, directly connected to a television set, is too expensive for most individuals.
Satellite (re)transmission to a satellite receiving dish or other suitable receiving antenna, connected to cable system a~ain is only suitable for large urban areas, given the necessary capital expense. These use VHF or UHF radio waves, along the cable.
Satellite (re)transmi3sion to a ~atellite receiving dish or other suitable antenna, connected to an MMDS
(Multi-channel Microwave Distribution Sy9tem5), which retransmits the satellite signal at a microwave frequency. Less power is required, typically a 30 watt MMDS output i~ equivalent to 100 watt3 of UHF output.
It is also cheaper than the equivalent cable system, . .
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bacause the capital expenditures, needed to acquire di~tribution systems, rights of way and the llke, are not required. ~ mlnor drawback i5 that only 31 microwave channels have been thus far authorlzed, for television transmission use.
The MMDS system, in view of capital and operating costs, is largely restricted to the large urban environment. The typical range o~ an MMDS system, allowing for line of sight, i5 75 to 3~ miles ~40 to 50 kilometers). In favorable terrain conditions, the effective reliable range of MMDS may be as much as 35 miles (5~ or so kilometers). Elsewhere, the population must rely on other method~ to receive a wlde range of television channels. The coverage area can be increased by increasing the height of the transmitting antenna, increasing the antenna gain, or decreasing the cable losses.
There is a demand for economic multi-channel transmission systems outside large urban centres. ~
' :
Solutions have been theoretically suggested. Lower power output o~ 1 watt per MMDS channel is one approach.
The expression "power output" as generally used in the art, commonly refers to the measured video power output.
The measured audio power output i5 much less than the video power output, being typically o~ the order of 15 decibels smaller. The measured video power output i8 thus a good approximation to total power output.
Another is to use higher mlcrowave frequencies, that is the 12 or 30 GHz bands, rather than the current
SHORT RANGE MULTI-CHANNEI, MICROWAV~ TRANSMITTER
This invention relates to short range multi-channel microwave transmitters. Partlcularly it relates to such transmitters adapted ~or transmission of television.
` BACKGROUND OF INVENTION
. , .
There is an increasin~ demand for multi-channel television reception.
At present television broadcasts are transmitted and received in several ways.
Direct transmission, or retransmission, from a transmission tower to a television aerial, is only suitable for large urban areas. These generally use VHF
or UHF radio waves (Very High Frequency or Ultra High Frequency).
Satellite (re)transmission, generally by mlcrowave to a satellite receiving dish, or a satellite receiver, directly connected to a television set, is too expensive for most individuals.
Satellite (re)transmission to a satellite receiving dish or other suitable receiving antenna, connected to cable system a~ain is only suitable for large urban areas, given the necessary capital expense. These use VHF or UHF radio waves, along the cable.
Satellite (re)transmi3sion to a ~atellite receiving dish or other suitable antenna, connected to an MMDS
(Multi-channel Microwave Distribution Sy9tem5), which retransmits the satellite signal at a microwave frequency. Less power is required, typically a 30 watt MMDS output i~ equivalent to 100 watt3 of UHF output.
It is also cheaper than the equivalent cable system, . .
: : .: - : : . : , . , `
... , ~ : : ` :
: . . , :`: ;
, ,~4~ r~F~
bacause the capital expenditures, needed to acquire di~tribution systems, rights of way and the llke, are not required. ~ mlnor drawback i5 that only 31 microwave channels have been thus far authorlzed, for television transmission use.
The MMDS system, in view of capital and operating costs, is largely restricted to the large urban environment. The typical range o~ an MMDS system, allowing for line of sight, i5 75 to 3~ miles ~40 to 50 kilometers). In favorable terrain conditions, the effective reliable range of MMDS may be as much as 35 miles (5~ or so kilometers). Elsewhere, the population must rely on other method~ to receive a wlde range of television channels. The coverage area can be increased by increasing the height of the transmitting antenna, increasing the antenna gain, or decreasing the cable losses.
There is a demand for economic multi-channel transmission systems outside large urban centres. ~
' :
Solutions have been theoretically suggested. Lower power output o~ 1 watt per MMDS channel is one approach.
The expression "power output" as generally used in the art, commonly refers to the measured video power output.
The measured audio power output i5 much less than the video power output, being typically o~ the order of 15 decibels smaller. The measured video power output i8 thus a good approximation to total power output.
Another is to use higher mlcrowave frequencies, that is the 12 or 30 GHz bands, rather than the current
2.5 GHz band. The 1 watt power outlet would enable short range coverage say 3 - 6 miles (5 - 10 km). The hi~her frequencies would allow use o~ readily available frequencles, as the frequencles ln the 2.5 GHz band may be assigned to radiotelephony and military applications.
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The problem with the proposed 1 watt power output is that combining the channels lnto a single MMDS
antenna greatly reduces effective channel transml~sion power. In prior art practice at least 10 watts per cha~nel are required and for larger area coveraye up to loO watts per channel. The problem with use of the higher micro~ave frequencies i8 path los~ i8 greater, 15 decibels greater loss over 5 miles (8 kllometers~ for 12 GHz than 2 GHz. Power requlrements are thus much greater at the higher frequencies, more so at 30 ~Hz than 12 GHz. Allowing for the cost of MMDS, and the expected necessary power usage, an economic form of MMDS is not practicable for the so-called theoretical "villaye"
level multi-channel transmiss~on system.
Another suggestion is to use UHF or VH~ radio transmission, which is effectively downscaling a normal television transmitter. This does not provide an economic solution Por s~all areas, because the increased path loss must be overcome by increased power output at the transmitting antenna. In order to have a noise free picture, which is acceptable to most customers, the transmitting equipment must be equivalent in standard to that of a normal te~evision transmitter suitable ~or a large city. At present equipment costs, this does not offer a "village" level multi-channel televl~ion distribution system.
The most desirable solution would be a modified and less expensive MMDS system capable of retransmitting at the 1 watt powcr level.
DESCRIPTION OF PRIOR ART
The original MDS (Microwave Di~tribution System) i8 single channel. It has a receiving antenna ~ystem, connected to a receiver. The receiver output i8 in turn passed through a modulator then optionally a band pass .... ,. ` . ~ . .
~ ' :.~-; ~: . ' ::: , :;
filter. The mc~dulator, and if present the band pass filter are all tuned to a single VHF or UHF
frequency. The output i9 next fed into a balanced modulator or ~ixer, which combine~ the VHF or ~HF with the output of a mlcrowave fr~quency oscillator, which creates mixer output of microwave carrier fre~uency equal to the UHF or VHF input carrier wave frequency plus the microwave oscillator frequency. The carrier frequency is modulated by the television audio and video lo frequencies. The microwave output may be optionally passed through a band pass filter tuned to the specific ~ microwave output frequency, at which point the output is ; fed through a power amplifier. The po~er amplifier output is then fed into the MDS transmitting antenna system.
- MMDS comprises a set of MDS systems in parallel one ~or each channel, with common receiviny and transmitting antennae. The receiving antenna system, which may be a microwave satellite dish, sends its output to an array of receiverC, each tuned to a specific television channel, satellite, YHF or UHP frequency. Each receiver output is in turn passed through a modulator then optionally a band pass filter. The modulator and if present the band pass filter are tuned to a single VHF
or UHF frequency. The output i3 next fed into a balanced modulator or mixer, which combine~ the VHF or UHF with the output of a microwave frequency oscillator, which creates mixer output of microwave carrier frequency equal to the UHF or VHF input carrier wave frequency plus the microwave oscillator frequency. The carrier frequency is modulated by the television audlo and video frequencies. The microwave output may be optionally pa~sed through a band pass ~ilter tuned to the speci~ic microwave output frequency, at which point the output is fed through a power amplifier. The power amplifier output i~ fed through a power combiner. The combined output of all the channels is then fed into the .. ..
: : : , . . : ..
.: : - , ':, ' 1 , ~ ' .. , :' ::- : ,-:,:: :.: . .:
: . .
- ~ .
MMDS transmitting antenna systam. Each channel of the multi-channel ~y~tem has an independent system includlng receivers, oscillators, mixers and band pass filters ~when present), until the power comblner before the antenna system. In some verslons the audio and video signals for each channel have separate system~ and are combined into a ~inyle output by a diplexer, be~ore the power combiner.
.
Other known retransmitting systems are used in telecommunication satellites. These receive microwave transmissions of higher frequency and retran~mit the transmissions a~ lower ~requencies. One system has a series of microwave receivers, each tuned to a specific microwave frequency. The received ~ignals are then heterodyned by passing throuyh a single multi-band mixer which combines the output oP a single oscillator, to produce a set o~ lower frequency output frequencies which are then fed to the transmitting antenna. The other system is more analogous to the prevlously described MMDS. It has a separate receiver, oscillator, and mixer for each microwave ~requency, the heterodyned lower freq~ency output~ being combined a~ter the mixer ; for retransmission at the antenna. These systems may be designed to handle up to 36 television channels at a time.
DESCRIPTION OF THE INVENTION
It is a prinslpal object of the invention to provide an improved television transmission device capable o~ effective low level power transmlssion.
Other objects of the invention will become apparent to those skilled :Ln the art by re~erence to the ~ollowing description, the accompanying drawings, and the appended claims.
In a broad aspect the invention i8 dlrected to an .:. :
.... . . . .
,~ :, .
improved frequency modulating device adapted to receive and convert at lea~t one input radlo frequency associated with a television channel, to at lea~t one output microwave frequency, each output microwave frequency corresponding to ~ ~pecific input radio frequency, a power ampllfier operatively associated with the frequency modulating device, the power amplifier being a~apted to amplify at least one output microwave frequency, and to feed at least one amplified output microwave frequency to a trans;mitting antenna, the improvement comprising the power amplifler-operating at about 2X of the rated output wattage of the 1 decibel compression point of the amplifier, whereby at ~ least one amplified output microwave frequency can be fed to the transmitting antenna at a power level of about 1 watt, per television channel.
In another broad aspect the invention i8 directed to an improved device adapted to transmit at least one 20 microwave frequency, the device comprising a frequency ::
modulating device adapted to receive and convert at ~ :
least one input radio frequency, assoclated with a television channel, to at least one output microwave frequency, each output microwave fre~uency corresponding to a specific input radio fre~uency, a power amplifier operatively associated with the fre~uency modulating device, the power amplifier being adapted to amplify at least one microwave frequency, and a transmitt~ng antenna operatively associated with the power amplifier, ~he antenna being adapted to transmit at lea~t one amplified output microwave frequency, the improvement comprising the power amplifier operating at about 2% of the rated output watta~e of the 1 decibel compression point o~ the amplifier, whereby at least one a~plified output microwave frequency can be fed to the transmitting antenna at a power level of about 1 watt, per television channel.
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In a further broad aspect the invention i3 directed to an improved microwave distributlon ~ystem including:
a receiving antenna feed system;
at least one reGeiver system operatlvely associated, wlth the antenna feed sy~tem, each the receiver system being tuned t~ a specific radio frequency corresponding to a specific television channel, and a transmitting antenna system;
. a frequency modulating device adapted to receive and convert at least one input radio frequency, each -corresponding to a specific televi~ion channel, to at least one output microwave frequency, each output microwave fre~uency correspondin~ to a.specific input radio fre~uency, a power amplifier operatively associated with the frequency modulatln~ device, the power ampli f ier being adapted to amplify at least one output microwave frequency, the transmitting antenna being operatively associated with the power amplifier, the transmitting antenna being adapted to transmit at least one amplified output microwave requency, the improvement comprisin~ the power ampli~ier -operating at about 2% of the rated output wattage of the 1 decibel compression point of the amplifier, whereby at least one amplified output microwave frequency can be transmitted to the transmitting antenna at a power leve?
of about 1 watt, per televlsion chan~el.
.
. In preferred form the power amplifier operates in the output range of about 1 watt, and -the rated output wattage of the 1 decibel compression point oP the amplifier is at least about 75 watts. Preferably the frequency modulating device has a first multi-channel band pass filter adapted to filter a plurality ~f output microwave frequencie3, operatively associated therewith.
Similarly the pow~r amplifier preferably has a second multi channel band pass filter adapted to ~ilter a plurality of amplifled output microwave ~requencies, operatively associated therewith. The ~requency . . .... . .... .
.. .: -. , -, , ~ , :
:~ :: . .:: : ~ : . .:
,, . ~ : . ':.
.. .
modulatc~r pre:~erat.)ly ha~; arl lsolator operativeJ.y associa-ted therewith, pasf~irlg the OUtpllt microwave frequency signals in one cl.irec:tion only, from the frequency moclula-tor toward the power amplifier.
PreEerably -the amplifler has a var.iable a-ttenua-tor operatively associated wi-th the input thereof.
Preferably the frequency moclulator includes an impedance transformer operatively associated therewith, adapted to transform the impedance of the plurallty oE radio frequencies, and a microwave frequency ~enerator operatively associated therewith, the microwave frequency generator comprising a local oscillator adaptecl to generate a microwave frec~uency, and an isolator adapted to pass the output microwave signal in one direction only, from the local oscillator toward the frequency modulator. Preferably the microwave distribution system is a multi-channel system, and includes a plurality of receiver systems, in parallel with each other, operatively associated with said receiving antenna system.
This invention thus allows capital cost reduction by reducing the number of frequency modulators and power amplifiers per channel, and power costs by reducing the necessary output power. Preferably there is one frequency modulator and power amplifier for each eight channels. The effective range of the device at 1 watt per channel, is usually between 3 and 5 miles (5 to 10 kilometers), under favorable terrain conditions as much as 8 miles (13 kilometers). An economic "village" level MMDS has thus been created.
The use oE the power amplifier at the low range of its effective power output, allows linear reproduction of inputs as amplified outputs without signiEicant c:ross modulation distortion products, alias intermodulation distortion products, virtually eliminat:ing noise due to production o~ undesired spurious frequencies. Normally .:~''.: " ', ''' ,: :.~ , :.
... ': ' ,.... . , , ,.,:
power amplifiers are used ne~r the line~rity-nonlinearity li~it for maximum power output, entailing some noi9e production.
In this invention the power amplifier typically operates up to about 1 watt output, while the linearity-nonlinearity limit (1 decibel compression polnt) i5 at least about ~5 watts rated output, there ~ no ne~e~sity to use such amplifiers. The amplifier can haye a higher linearity-nonlinearity limit tl dec~bel compres~lon point), although ~or economic reasons this limit should be as low as feasible.
A test version using an amplifier with 10 watts rated output at the linearity-nonlinearity limit (1 decibel compression point) proved ine~fectlve at about 1 watt power output. The noise level was unacceptable.
It was considered in view of this experiment, that the use of an amplifier with 50 watts rated output at the linearity-nonlinearity limit (1 decibel compression point) would prove ineffective at about 1 watt power ;~ output, while the use of an amplifier with 75 watts rated QUtpUt at the linearity-nonlinearity limit ~1 decibel compression point? would prove effective at about 1 watt power output.
The amplifier rated at 75 watts was tested and found to perPorm satisfactorily, at 1 watt power output.
The 1 watt power output gave the best performance.
Hi~her power outputs would lead to increased covera~e area, but the cost would increase sub~tantially depending on the number o~ television channels accommodated, above the 2 to 3 watt output level.
The function o~ the isolator i~ to act a~ a complex one way valve, allowing current to move towards the transmission antenna, ~rom the microwave oscillator, or the band modulator (mixer). The functlon of the variable attenuator is to ensure that the input level~ are ~:. . , : - ,. , .::, : , ,,. ,.. , . . :
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~n~ 3~
The problem with the proposed 1 watt power output is that combining the channels lnto a single MMDS
antenna greatly reduces effective channel transml~sion power. In prior art practice at least 10 watts per cha~nel are required and for larger area coveraye up to loO watts per channel. The problem with use of the higher micro~ave frequencies i8 path los~ i8 greater, 15 decibels greater loss over 5 miles (8 kllometers~ for 12 GHz than 2 GHz. Power requlrements are thus much greater at the higher frequencies, more so at 30 ~Hz than 12 GHz. Allowing for the cost of MMDS, and the expected necessary power usage, an economic form of MMDS is not practicable for the so-called theoretical "villaye"
level multi-channel transmiss~on system.
Another suggestion is to use UHF or VH~ radio transmission, which is effectively downscaling a normal television transmitter. This does not provide an economic solution Por s~all areas, because the increased path loss must be overcome by increased power output at the transmitting antenna. In order to have a noise free picture, which is acceptable to most customers, the transmitting equipment must be equivalent in standard to that of a normal te~evision transmitter suitable ~or a large city. At present equipment costs, this does not offer a "village" level multi-channel televl~ion distribution system.
The most desirable solution would be a modified and less expensive MMDS system capable of retransmitting at the 1 watt powcr level.
DESCRIPTION OF PRIOR ART
The original MDS (Microwave Di~tribution System) i8 single channel. It has a receiving antenna ~ystem, connected to a receiver. The receiver output i8 in turn passed through a modulator then optionally a band pass .... ,. ` . ~ . .
~ ' :.~-; ~: . ' ::: , :;
filter. The mc~dulator, and if present the band pass filter are all tuned to a single VHF or UHF
frequency. The output i9 next fed into a balanced modulator or ~ixer, which combine~ the VHF or ~HF with the output of a mlcrowave fr~quency oscillator, which creates mixer output of microwave carrier fre~uency equal to the UHF or VHF input carrier wave frequency plus the microwave oscillator frequency. The carrier frequency is modulated by the television audio and video lo frequencies. The microwave output may be optionally passed through a band pass filter tuned to the specific ~ microwave output frequency, at which point the output is ; fed through a power amplifier. The po~er amplifier output is then fed into the MDS transmitting antenna system.
- MMDS comprises a set of MDS systems in parallel one ~or each channel, with common receiviny and transmitting antennae. The receiving antenna system, which may be a microwave satellite dish, sends its output to an array of receiverC, each tuned to a specific television channel, satellite, YHF or UHP frequency. Each receiver output is in turn passed through a modulator then optionally a band pass filter. The modulator and if present the band pass filter are tuned to a single VHF
or UHF frequency. The output i3 next fed into a balanced modulator or mixer, which combine~ the VHF or UHF with the output of a microwave frequency oscillator, which creates mixer output of microwave carrier frequency equal to the UHF or VHF input carrier wave frequency plus the microwave oscillator frequency. The carrier frequency is modulated by the television audlo and video frequencies. The microwave output may be optionally pa~sed through a band pass ~ilter tuned to the speci~ic microwave output frequency, at which point the output is fed through a power amplifier. The power amplifier output i~ fed through a power combiner. The combined output of all the channels is then fed into the .. ..
: : : , . . : ..
.: : - , ':, ' 1 , ~ ' .. , :' ::- : ,-:,:: :.: . .:
: . .
- ~ .
MMDS transmitting antenna systam. Each channel of the multi-channel ~y~tem has an independent system includlng receivers, oscillators, mixers and band pass filters ~when present), until the power comblner before the antenna system. In some verslons the audio and video signals for each channel have separate system~ and are combined into a ~inyle output by a diplexer, be~ore the power combiner.
.
Other known retransmitting systems are used in telecommunication satellites. These receive microwave transmissions of higher frequency and retran~mit the transmissions a~ lower ~requencies. One system has a series of microwave receivers, each tuned to a specific microwave frequency. The received ~ignals are then heterodyned by passing throuyh a single multi-band mixer which combines the output oP a single oscillator, to produce a set o~ lower frequency output frequencies which are then fed to the transmitting antenna. The other system is more analogous to the prevlously described MMDS. It has a separate receiver, oscillator, and mixer for each microwave ~requency, the heterodyned lower freq~ency output~ being combined a~ter the mixer ; for retransmission at the antenna. These systems may be designed to handle up to 36 television channels at a time.
DESCRIPTION OF THE INVENTION
It is a prinslpal object of the invention to provide an improved television transmission device capable o~ effective low level power transmlssion.
Other objects of the invention will become apparent to those skilled :Ln the art by re~erence to the ~ollowing description, the accompanying drawings, and the appended claims.
In a broad aspect the invention i8 dlrected to an .:. :
.... . . . .
,~ :, .
improved frequency modulating device adapted to receive and convert at lea~t one input radlo frequency associated with a television channel, to at lea~t one output microwave frequency, each output microwave frequency corresponding to ~ ~pecific input radio frequency, a power ampllfier operatively associated with the frequency modulating device, the power amplifier being a~apted to amplify at least one output microwave frequency, and to feed at least one amplified output microwave frequency to a trans;mitting antenna, the improvement comprising the power amplifler-operating at about 2X of the rated output wattage of the 1 decibel compression point of the amplifier, whereby at ~ least one amplified output microwave frequency can be fed to the transmitting antenna at a power level of about 1 watt, per television channel.
In another broad aspect the invention i8 directed to an improved device adapted to transmit at least one 20 microwave frequency, the device comprising a frequency ::
modulating device adapted to receive and convert at ~ :
least one input radio frequency, assoclated with a television channel, to at least one output microwave frequency, each output microwave fre~uency corresponding to a specific input radio fre~uency, a power amplifier operatively associated with the fre~uency modulating device, the power amplifier being adapted to amplify at least one microwave frequency, and a transmitt~ng antenna operatively associated with the power amplifier, ~he antenna being adapted to transmit at lea~t one amplified output microwave frequency, the improvement comprising the power amplifier operating at about 2% of the rated output watta~e of the 1 decibel compression point o~ the amplifier, whereby at least one a~plified output microwave frequency can be fed to the transmitting antenna at a power level of about 1 watt, per television channel.
r.; .
.':''' ' " ' ,.. , .. ' . ': .: ' ' " ' ' ' ' . ' .. . . . . . . . .
' : . .: . . . ' ' ~ . ' ' : :
:. .; ~ .-' : .. ' : ' : , . .
i i . ~ . :
.' ' . ' - .: ., . ~ ' .
~ ' ' ' '' ' ' ' ~ ' ' : .
~nq~
In a further broad aspect the invention i3 directed to an improved microwave distributlon ~ystem including:
a receiving antenna feed system;
at least one reGeiver system operatlvely associated, wlth the antenna feed sy~tem, each the receiver system being tuned t~ a specific radio frequency corresponding to a specific television channel, and a transmitting antenna system;
. a frequency modulating device adapted to receive and convert at least one input radio frequency, each -corresponding to a specific televi~ion channel, to at least one output microwave frequency, each output microwave fre~uency correspondin~ to a.specific input radio fre~uency, a power amplifier operatively associated with the frequency modulatln~ device, the power ampli f ier being adapted to amplify at least one output microwave frequency, the transmitting antenna being operatively associated with the power amplifier, the transmitting antenna being adapted to transmit at least one amplified output microwave requency, the improvement comprisin~ the power ampli~ier -operating at about 2% of the rated output wattage of the 1 decibel compression point of the amplifier, whereby at least one amplified output microwave frequency can be transmitted to the transmitting antenna at a power leve?
of about 1 watt, per televlsion chan~el.
.
. In preferred form the power amplifier operates in the output range of about 1 watt, and -the rated output wattage of the 1 decibel compression point oP the amplifier is at least about 75 watts. Preferably the frequency modulating device has a first multi-channel band pass filter adapted to filter a plurality ~f output microwave frequencie3, operatively associated therewith.
Similarly the pow~r amplifier preferably has a second multi channel band pass filter adapted to ~ilter a plurality of amplifled output microwave ~requencies, operatively associated therewith. The ~requency . . .... . .... .
.. .: -. , -, , ~ , :
:~ :: . .:: : ~ : . .:
,, . ~ : . ':.
.. .
modulatc~r pre:~erat.)ly ha~; arl lsolator operativeJ.y associa-ted therewith, pasf~irlg the OUtpllt microwave frequency signals in one cl.irec:tion only, from the frequency moclula-tor toward the power amplifier.
PreEerably -the amplifler has a var.iable a-ttenua-tor operatively associated wi-th the input thereof.
Preferably the frequency moclulator includes an impedance transformer operatively associated therewith, adapted to transform the impedance of the plurallty oE radio frequencies, and a microwave frequency ~enerator operatively associated therewith, the microwave frequency generator comprising a local oscillator adaptecl to generate a microwave frec~uency, and an isolator adapted to pass the output microwave signal in one direction only, from the local oscillator toward the frequency modulator. Preferably the microwave distribution system is a multi-channel system, and includes a plurality of receiver systems, in parallel with each other, operatively associated with said receiving antenna system.
This invention thus allows capital cost reduction by reducing the number of frequency modulators and power amplifiers per channel, and power costs by reducing the necessary output power. Preferably there is one frequency modulator and power amplifier for each eight channels. The effective range of the device at 1 watt per channel, is usually between 3 and 5 miles (5 to 10 kilometers), under favorable terrain conditions as much as 8 miles (13 kilometers). An economic "village" level MMDS has thus been created.
The use oE the power amplifier at the low range of its effective power output, allows linear reproduction of inputs as amplified outputs without signiEicant c:ross modulation distortion products, alias intermodulation distortion products, virtually eliminat:ing noise due to production o~ undesired spurious frequencies. Normally .:~''.: " ', ''' ,: :.~ , :.
... ': ' ,.... . , , ,.,:
power amplifiers are used ne~r the line~rity-nonlinearity li~it for maximum power output, entailing some noi9e production.
In this invention the power amplifier typically operates up to about 1 watt output, while the linearity-nonlinearity limit (1 decibel compression polnt) i5 at least about ~5 watts rated output, there ~ no ne~e~sity to use such amplifiers. The amplifier can haye a higher linearity-nonlinearity limit tl dec~bel compres~lon point), although ~or economic reasons this limit should be as low as feasible.
A test version using an amplifier with 10 watts rated output at the linearity-nonlinearity limit (1 decibel compression point) proved ine~fectlve at about 1 watt power output. The noise level was unacceptable.
It was considered in view of this experiment, that the use of an amplifier with 50 watts rated output at the linearity-nonlinearity limit (1 decibel compression point) would prove ineffective at about 1 watt power ;~ output, while the use of an amplifier with 75 watts rated QUtpUt at the linearity-nonlinearity limit ~1 decibel compression point? would prove effective at about 1 watt power output.
The amplifier rated at 75 watts was tested and found to perPorm satisfactorily, at 1 watt power output.
The 1 watt power output gave the best performance.
Hi~her power outputs would lead to increased covera~e area, but the cost would increase sub~tantially depending on the number o~ television channels accommodated, above the 2 to 3 watt output level.
The function o~ the isolator i~ to act a~ a complex one way valve, allowing current to move towards the transmission antenna, ~rom the microwave oscillator, or the band modulator (mixer). The functlon of the variable attenuator is to ensure that the input level~ are ~:. . , : - ,. , .::, : , ,,. ,.. , . . :
,: :, . . - ::. . . : - . : : .: : . ~
3~
~uitabl~ for ampli~ication by the power amylifier, by reducing input amplitudes, when necessary.
As would be appreciated by tho~e skilled in the art, a~ at pre3ent only 31 micr-owave frequency channel~
are assigned to television transmis~ion, only 31 such channels can be used by an MMDS antenna. The present invention is basically directed to combination of up to 8 radio freq~ency inputs through a single microwave frequency mod~lator. This arrangement has thus ~ar proved experimentally satisfactory.
As would be appreciated by those skilled in the art more microwave ~requency channels could be utilized. One approach would be to use more radio freyuency inputs through a single microwave frequency modulator. Another approach, at present preferred, would be to u~e up to 4 microwave frequency modulator~ utilizing the same transmitting antenna, with up to 8 radlo fre~uency inputs per microwave fre~uency modulator. Thi3 arrangement c~uld b~ expanded, should more microwave frequency channels be released for television, either by utilizing more inputs per microwave frequency modulator, or by increasing the number o~ microwave frequency modulators.
DESCRIPTION OF THE PREFERR~D EMBODIMENTS
Preferred embodiments are ind~cated ln the drawings where:
Fig. l is a schematlc circuit diagram of a prior art multi-channel microwave distributlon sy~tem (MNDS), which can also with a component change be an embodiment of a multi-channel microwave distribution sy~tem of the inventlon;
Fig. 2 is a schematic circuit diagram of a preferred multi-channel mIcrowave distribution ~ystem of the invention.
: , ;. . , .:: , . , . . .
~ '2~
The ~eneral description o~ the inventlon 18 now expanded by reference to the drawing~, which illustrate prePerred embodiments of the invention. Although in both Fiyures the systems are indicated a8 8 channel systems, neither device is so restricted in practice.
In both Figs. 1 and 2, numeral 10 indicates a conventional aerial feed system. For instance 10 may be a conventional television antenna, feeding to an eight way power splitter, optionally with a wide band amplifier between antenna and splitter. An alternatlve version would include a satellite feed system, which, for example, separates the vertical and horizontal wave components, and then ~eeds them through separate low noise block down converters to four way power splitters, and thence to channel fre~uency receivers. Grounded shielded coaxial cables 11, connect the component devices. Eight receivers 12, 2~, 32, 42, 62, 62, 72, 82 each tuned to a different television chann~l ~re~uency receive the output of antenna system 10, and isolat2 one channel frequency output. These outputs are then passed through the corresponding single channel modulators, 13, 23, 33, 43, 53, 63, 73, 83, which are tuned to the corresponding channel frequency. These modulator~' primary function is to convert the television audio and video signals to VHF frequencies for television set input. These modulators may al90 be selected to adapt a television signal originati~g within one television system with one set of standards, to a different television signal, acceptable to a local tel~vision system, based on a dif~erent set o~ standards. The output of these modulators i5 passed optionally through corresponding single channel band pass ~ilters 14, 24, 34, 44, 54, 6~, ~4, 84, which if pre~ent are tuned to the corresponding channel ~requency. Thus ~ar the device structure is identical. In Fig. 1, showing the prlor art MMDS, mixers or bala~ce modulator~, 15, 25, 35, 45, 55, 65, Y5, 85, mlx the incoming slgnal wlth a ?~
. ~ . ' , :' . ' .
.
standard microwave frec~uency yenerated respectively by local oscillators 101, 102, 103, 104, 105, 106, 107, 108, which are powered respectively by DC power supplies 91, 92, 93, 94, 95, 96, 97, 98, through cables g9.
Isola-tors 111, 112, 113, 114, 115, 116, 117, 118, feecl the oscillator o-utput freque~y into mixers 15, 2S, 35, 45, 55, 65, 75, 85 respectively. The mixer output i5 then passed respectively through isolators 16, 26, 36, 46, 56, 66, 76, 86, and single channel bancl pass filters ; 10 17, 27, 37, 47, 57, 6~, 77, 87, which are individually tuned to the specific output frequencie~ of the respective mixers 15, 25, 35, 45, 65, 65, 75, 85. Next after -these band pass filters the outputs are fed through variable attenuators 18, 28, 3~, 48, 58, 68, 78, 88, into power amplifiers 19, 29, 39, 49, 59, 69, 79, 89, respectively. The amplified outputs then pass through single band pass filte:rs 20, 30, 40, 50, 60, 70, 80, 90, respectively into eight way power combiner 110, and thence into conventional microwave anterlna system 120. Fig. 1, thus indicates the prior art system.
Ficg. ~ is identical ~rom receiving system 10 to individually tuned modulators 13, 23, 33, 43, 53, 63, 73, 83, and when present optional individually tuned band pass filters 14, 24, 34, 44, 54, 64, 74, 84. The output signals are then combined through eight way combiner 110, and the combined outputs are fed through impedance transformer 200 to balance modulator or mixer 205, which is supplied through isolator 211, by local oscillator 201, which is powered by DC supply 100 through cable 99. The arrangements after balance modulator or mixer 205, are superficially similar to that of balance modulators 15, 25, 35, 45, 55, 65, 75, 85, but dif~er in detail. Isolator 206 is essentially similar to isolators 16, 26, 36, 46, 56, 66, 76, 86.
Band pass ~ilter 207, is distinct from, bancl pass filters ~, 17, 27, 37, 47, 57, 67, 77, 87, which are tuned to a sinyle frequency and cannot work unless they are. Band pass filter 207 is a multi-channel band pass filter and ?' '. ', ' ~ . - . , ' ~ . ~ ` i ;`':, , . ' ' :
,~J~)r1 can be tuned to cover all eight ~pecific ~rcqu~ncie~
simultaneously, lt cannot work otherwi~e. Variable att~nuator 208 i5 ess~ntlally ~imllar to variabl~
attenuators 18, 28, 3a, 4a, 5~, 6~ , 88. Power amplifier 209 i9 d~tlnct from power amplifiers 19, 29, 39, 49, 59, 69, ~9, 89. Band pass filter 210 i5 like band pass fllter 207, which fulfills the identlcal ~unction of a multi-channel band pasq ~ilter, unli~e the single channel band pass filter~ 20, 30, 40, 50, 60, ~0, 10 80, 90. Microwave antenna systern 220 i8 conventiotlal, and similar to microwave antenna system 120, with conventional differences to allow Por the lower energy output.
Power amplifier 209 is distinct from the normal power amplifiers, which are traditionally utilized near the conversion boundary, where power output ceases to be a linear function of power input, and instead becomes a : nonlinear function o~ power input. This allows maximum linear power output. Power ampli~ier 209 i8 run at approximately 2% of maximum linear power output, which allows for very precise linear power ampli~ication, this al~o virtually eliminates intermodulation distortlon by the amplifier, and reduces signal noise when operated well below the 1 decibel compression point.
Flg. 1 also represents an embodiment of the pre~ent invention ~imply by using the ampli~ier type o~ power amplifier 209, as power amplifiers 19, 29, 39, 49, 59, 69, ~9, B9, i~ place of the normal power amplifiers used in the standard MMDS. The other components would remain unchanged. This solution while satlsfactory as to power usage, is ~uch less so when initial capltal cost i~
considered.
Exemplary components utillzed in the preferred 0mbodiment~ are indicated below, this 1~ lllustrative .- , .
: ' : . , ' . , ': ' ' .
.r,~ . `
,, ~ .
"' ' :
.~, . . ' , ' , .
. .
Receivlng feed system lO, and receivers 12, 22, 32, 42, 52, 62, 72, 82, modulators 13, 23, 33, 43, 53, 63, ~3, ; 83, and single ~hannel ban~ pass fllter~ 4, 3~, 44, 5~, 64, 74, 84, are conventional in nature and may be used in either a standard MMDS or the MMDS of thls invention. The transformer 200 changes impedance from 75 to 50 ohm~, and is conventional in nature. The local oscillator 201 is a 2332 MHz CTI P-23XX, isolators 211 and 206 are both Innowave 1026 I:K. The multi-channel band pass ~ilters 207 and 210 ar~ both Microwave Filter Co. 6913. The balanced modulator or mixer 205, is an Anaren ~0666, while the varlable attenuator ls an Alan 50CA 4-20. The power amplifier is an SSPA 6200 amplifier, which has excellent llnearity at 1 watt output, and a 75 watt linearity-nonlinearity output limit. As would be appreciated by those skilled in the art, similar components functioning in a similar fashion can be substituted as long as they have the identical or sufPlciently simllar specifications and general performance functions.
~, Although this invention ls described in terms o~
~pecific embodlments, it is not limited thereto, as would be understood by those skilled ln the art, numerous variations are possible within the scope of the invention as described and claimed in the application, without departing from the scope and nature thereof.
lg ~:
~,............................... .
:l ~ :
:: . .. . . .. . , . :
.: : : : . . . .
: , , - . . .
.~ ;. . - ~ , : .
~uitabl~ for ampli~ication by the power amylifier, by reducing input amplitudes, when necessary.
As would be appreciated by tho~e skilled in the art, a~ at pre3ent only 31 micr-owave frequency channel~
are assigned to television transmis~ion, only 31 such channels can be used by an MMDS antenna. The present invention is basically directed to combination of up to 8 radio freq~ency inputs through a single microwave frequency mod~lator. This arrangement has thus ~ar proved experimentally satisfactory.
As would be appreciated by those skilled in the art more microwave ~requency channels could be utilized. One approach would be to use more radio freyuency inputs through a single microwave frequency modulator. Another approach, at present preferred, would be to u~e up to 4 microwave frequency modulator~ utilizing the same transmitting antenna, with up to 8 radlo fre~uency inputs per microwave fre~uency modulator. Thi3 arrangement c~uld b~ expanded, should more microwave frequency channels be released for television, either by utilizing more inputs per microwave frequency modulator, or by increasing the number o~ microwave frequency modulators.
DESCRIPTION OF THE PREFERR~D EMBODIMENTS
Preferred embodiments are ind~cated ln the drawings where:
Fig. l is a schematlc circuit diagram of a prior art multi-channel microwave distributlon sy~tem (MNDS), which can also with a component change be an embodiment of a multi-channel microwave distribution sy~tem of the inventlon;
Fig. 2 is a schematic circuit diagram of a preferred multi-channel mIcrowave distribution ~ystem of the invention.
: , ;. . , .:: , . , . . .
~ '2~
The ~eneral description o~ the inventlon 18 now expanded by reference to the drawing~, which illustrate prePerred embodiments of the invention. Although in both Fiyures the systems are indicated a8 8 channel systems, neither device is so restricted in practice.
In both Figs. 1 and 2, numeral 10 indicates a conventional aerial feed system. For instance 10 may be a conventional television antenna, feeding to an eight way power splitter, optionally with a wide band amplifier between antenna and splitter. An alternatlve version would include a satellite feed system, which, for example, separates the vertical and horizontal wave components, and then ~eeds them through separate low noise block down converters to four way power splitters, and thence to channel fre~uency receivers. Grounded shielded coaxial cables 11, connect the component devices. Eight receivers 12, 2~, 32, 42, 62, 62, 72, 82 each tuned to a different television chann~l ~re~uency receive the output of antenna system 10, and isolat2 one channel frequency output. These outputs are then passed through the corresponding single channel modulators, 13, 23, 33, 43, 53, 63, 73, 83, which are tuned to the corresponding channel frequency. These modulator~' primary function is to convert the television audio and video signals to VHF frequencies for television set input. These modulators may al90 be selected to adapt a television signal originati~g within one television system with one set of standards, to a different television signal, acceptable to a local tel~vision system, based on a dif~erent set o~ standards. The output of these modulators i5 passed optionally through corresponding single channel band pass ~ilters 14, 24, 34, 44, 54, 6~, ~4, 84, which if pre~ent are tuned to the corresponding channel ~requency. Thus ~ar the device structure is identical. In Fig. 1, showing the prlor art MMDS, mixers or bala~ce modulator~, 15, 25, 35, 45, 55, 65, Y5, 85, mlx the incoming slgnal wlth a ?~
. ~ . ' , :' . ' .
.
standard microwave frec~uency yenerated respectively by local oscillators 101, 102, 103, 104, 105, 106, 107, 108, which are powered respectively by DC power supplies 91, 92, 93, 94, 95, 96, 97, 98, through cables g9.
Isola-tors 111, 112, 113, 114, 115, 116, 117, 118, feecl the oscillator o-utput freque~y into mixers 15, 2S, 35, 45, 55, 65, 75, 85 respectively. The mixer output i5 then passed respectively through isolators 16, 26, 36, 46, 56, 66, 76, 86, and single channel bancl pass filters ; 10 17, 27, 37, 47, 57, 6~, 77, 87, which are individually tuned to the specific output frequencie~ of the respective mixers 15, 25, 35, 45, 65, 65, 75, 85. Next after -these band pass filters the outputs are fed through variable attenuators 18, 28, 3~, 48, 58, 68, 78, 88, into power amplifiers 19, 29, 39, 49, 59, 69, 79, 89, respectively. The amplified outputs then pass through single band pass filte:rs 20, 30, 40, 50, 60, 70, 80, 90, respectively into eight way power combiner 110, and thence into conventional microwave anterlna system 120. Fig. 1, thus indicates the prior art system.
Ficg. ~ is identical ~rom receiving system 10 to individually tuned modulators 13, 23, 33, 43, 53, 63, 73, 83, and when present optional individually tuned band pass filters 14, 24, 34, 44, 54, 64, 74, 84. The output signals are then combined through eight way combiner 110, and the combined outputs are fed through impedance transformer 200 to balance modulator or mixer 205, which is supplied through isolator 211, by local oscillator 201, which is powered by DC supply 100 through cable 99. The arrangements after balance modulator or mixer 205, are superficially similar to that of balance modulators 15, 25, 35, 45, 55, 65, 75, 85, but dif~er in detail. Isolator 206 is essentially similar to isolators 16, 26, 36, 46, 56, 66, 76, 86.
Band pass ~ilter 207, is distinct from, bancl pass filters ~, 17, 27, 37, 47, 57, 67, 77, 87, which are tuned to a sinyle frequency and cannot work unless they are. Band pass filter 207 is a multi-channel band pass filter and ?' '. ', ' ~ . - . , ' ~ . ~ ` i ;`':, , . ' ' :
,~J~)r1 can be tuned to cover all eight ~pecific ~rcqu~ncie~
simultaneously, lt cannot work otherwi~e. Variable att~nuator 208 i5 ess~ntlally ~imllar to variabl~
attenuators 18, 28, 3a, 4a, 5~, 6~ , 88. Power amplifier 209 i9 d~tlnct from power amplifiers 19, 29, 39, 49, 59, 69, ~9, 89. Band pass filter 210 i5 like band pass fllter 207, which fulfills the identlcal ~unction of a multi-channel band pasq ~ilter, unli~e the single channel band pass filter~ 20, 30, 40, 50, 60, ~0, 10 80, 90. Microwave antenna systern 220 i8 conventiotlal, and similar to microwave antenna system 120, with conventional differences to allow Por the lower energy output.
Power amplifier 209 is distinct from the normal power amplifiers, which are traditionally utilized near the conversion boundary, where power output ceases to be a linear function of power input, and instead becomes a : nonlinear function o~ power input. This allows maximum linear power output. Power ampli~ier 209 i8 run at approximately 2% of maximum linear power output, which allows for very precise linear power ampli~ication, this al~o virtually eliminates intermodulation distortlon by the amplifier, and reduces signal noise when operated well below the 1 decibel compression point.
Flg. 1 also represents an embodiment of the pre~ent invention ~imply by using the ampli~ier type o~ power amplifier 209, as power amplifiers 19, 29, 39, 49, 59, 69, ~9, B9, i~ place of the normal power amplifiers used in the standard MMDS. The other components would remain unchanged. This solution while satlsfactory as to power usage, is ~uch less so when initial capltal cost i~
considered.
Exemplary components utillzed in the preferred 0mbodiment~ are indicated below, this 1~ lllustrative .- , .
: ' : . , ' . , ': ' ' .
.r,~ . `
,, ~ .
"' ' :
.~, . . ' , ' , .
. .
Receivlng feed system lO, and receivers 12, 22, 32, 42, 52, 62, 72, 82, modulators 13, 23, 33, 43, 53, 63, ~3, ; 83, and single ~hannel ban~ pass fllter~ 4, 3~, 44, 5~, 64, 74, 84, are conventional in nature and may be used in either a standard MMDS or the MMDS of thls invention. The transformer 200 changes impedance from 75 to 50 ohm~, and is conventional in nature. The local oscillator 201 is a 2332 MHz CTI P-23XX, isolators 211 and 206 are both Innowave 1026 I:K. The multi-channel band pass ~ilters 207 and 210 ar~ both Microwave Filter Co. 6913. The balanced modulator or mixer 205, is an Anaren ~0666, while the varlable attenuator ls an Alan 50CA 4-20. The power amplifier is an SSPA 6200 amplifier, which has excellent llnearity at 1 watt output, and a 75 watt linearity-nonlinearity output limit. As would be appreciated by those skilled in the art, similar components functioning in a similar fashion can be substituted as long as they have the identical or sufPlciently simllar specifications and general performance functions.
~, Although this invention ls described in terms o~
~pecific embodlments, it is not limited thereto, as would be understood by those skilled ln the art, numerous variations are possible within the scope of the invention as described and claimed in the application, without departing from the scope and nature thereof.
lg ~:
~,............................... .
:l ~ :
:: . .. . . .. . , . :
.: : : : . . . .
: , , - . . .
.~ ;. . - ~ , : .
Claims (20)
1. In a frequency modulating device adapted to receive and convert at least one input radio frequency associated with a television channel, to at least one output microwave frequency, each output microwave frequency corresponding to a specific input radio frequency, a power amplifier operatively associated with said frequency modulating device, said power amplifier being adapted to amplify said at least one output microwave frequency, and to feed at least one amplified output microwave frequency to a transmitting antenna, the improvement comprising said power amplifier operating at about 2% of the rated output wattage of the 1 decibel compression point of said amplifier, whereby said at least one amplified output microwave frequency can be fed to said transmitting antenna at a power level of about 1 watt, per television channel.
2. The device of claim 1, wherein said power amplifier operates in the output range of about 1 watt, and said rated output wattage of the 1 decibel compression point of said amplifier is at least about 75 watts.
3. The device of claim 2, wherein said frequency modulating device has a first multi-channel band pass filter, operatively associated therewith, adapted to filter a plurality of output microwave frequencies.
4. The device of claim 3, wherein said power amplifier has a second multi-channel band pass filter, operatively associated therewith, adapted to filter said plurality of amplified output microwave frequencies.
5. The device of claim 4, wherein said frequency modulator has an isolator operatively associated therewith, adapted to pass said output microwave frequencies only in the direction from said frequency modulator toward said power amplifier.
6. The device of claim 5, wherein said amplifier has a variable attenuator operatively associated with the input thereof.
7. The device of claim 6, wherein said frequency modulator has an impedance transformer operatively associated therewith, adapted to transform the impedance of said plurality of radio frequencies, and a microwave frequency generator operatively associated therewith, said microwave frequency generator comprising a local oscillator adapted to generate a microwave frequency, and an isolator adapted to pass said microwave frequency only in the direction from said local oscillator toward said frequency modulator.
8. In a device adapted to transmit at least one microwave frequency, said device comprising a frequency modulating device adapted to receive and convert at least one input radio frequency, associated with a television channel, to at least one output microwave frequency, each output microwave frequency corresponding to a specific input radio frequency, a power amplifier operatively associated with said frequency modulating device, said power amplifier being adapted to amplify at least one microwave frequency, and a transmitting antenna operatively associated with said power amplifier, said antenna being adapted to transmit at least one amplified output microwave frequency.
the improvement comprising said power amplifier operating at about 2% of the rated output wattage of the 1 decibel compression point of said amplifier, whereby said at least one amplified output microwave frequency can be fed to said transmitting antenna at a power level of about 1 watt, per television channel.
the improvement comprising said power amplifier operating at about 2% of the rated output wattage of the 1 decibel compression point of said amplifier, whereby said at least one amplified output microwave frequency can be fed to said transmitting antenna at a power level of about 1 watt, per television channel.
9. The device of claim 8, wherein said power amplifier operates in the output range of about 1 watt, and said rated output wattage of the 1 decibel compression point of said amplifier is at least about 75 watts.
10. The device of claim 9, wherein said frequency modulating device has a first multi-channel band pass filter, operatively associated therewith, adapted to filter a plurality of output microwave frequencies.
11. The device of claim 10, wherein said power amplifier has a second multi-channel band pass filter, operatively associated therewith, adapted to filter said plurality of amplified output microwave frequencies.
12. The device of claim 11, wherein said frequency modulator has an isolator operatively associated therewith, adapted to pass said output microwave frequencies only in the direction from said frequency modulator toward said power amplifier.
13. The device of claim 12, wherein said amplifier has a variable attenuator operatively associated with the input thereof.
14. In a microwave distribution system including:
a receiving antenna feed system;
at least one receiver system operatively associated, with said antenna feed system, each said receiver system being tuned to a specific radio frequency corresponding to a specific television channel, and a transmitting antenna system;
a frequency modulating device adapted to receive and convert at least one input radio frequency, each corresponding to a specific television channel, to at least one output microwave frequency, each corresponding to a specific input radio frequency, a power amplifier operatively associated with said frequency modulating device, said power amplifier being adapted to amplify said at least one output microwave frequency, said transmitting antenna being operatively associated with said power amplifier, said transmitting antenna being adapted to transmit at least one amplified output microwave frequency, the improvement comprising said power amplifier operating at about 2% of output wattage of the 1 decibel compression point of said amplifier, whereby said at least one amplified output microwave frequency can be transmitted to said transmitting antenna at a power level of about 1 watt, per television channel.
a receiving antenna feed system;
at least one receiver system operatively associated, with said antenna feed system, each said receiver system being tuned to a specific radio frequency corresponding to a specific television channel, and a transmitting antenna system;
a frequency modulating device adapted to receive and convert at least one input radio frequency, each corresponding to a specific television channel, to at least one output microwave frequency, each corresponding to a specific input radio frequency, a power amplifier operatively associated with said frequency modulating device, said power amplifier being adapted to amplify said at least one output microwave frequency, said transmitting antenna being operatively associated with said power amplifier, said transmitting antenna being adapted to transmit at least one amplified output microwave frequency, the improvement comprising said power amplifier operating at about 2% of output wattage of the 1 decibel compression point of said amplifier, whereby said at least one amplified output microwave frequency can be transmitted to said transmitting antenna at a power level of about 1 watt, per television channel.
15. The device of claim 14, wherein said microwave distribution system is a multi-channel system, and includes a plurality of receiver systems, in parallel with each other, operatively associated with said receiving antenna system.
16. The device of claim 14, wherein said power amplifier operates in the output range of about 1 watt, and said rated output wattage of the 1 decibel compression point of said amplifier is at least about 75 watts.
17. The device of claim 16, wherein said frequency modulating device has a first multi-channel band pass filter, operatively associated therewith, adapted to filter a plurality of output microwave frequencies.
18. The device of claim 17, wherein said power amplifier has a second multi-channel band pass filter, operatively associated therewith, adapted to filter said plurality of amplified output microwave frequencies.
19. The device of claim 18, wherein said frequency modulator has an isolator operatively associated therewith, adapted to pass said output microwave frequencies only in the direction from said frequency modulator toward said power amplifier.
20. The device of claim 19, wherein said amplifier has a variable attenuator operatively associated with the input thereof.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002001308A CA2001308A1 (en) | 1989-10-24 | 1989-10-24 | Short range multi-channel microwave transmitter |
| JP2008576A JPH03145829A (en) | 1989-10-24 | 1990-01-19 | Short distance multichannel microwave transmitting equipment |
| IL96078A IL96078A0 (en) | 1989-10-24 | 1990-10-22 | Short-range multi-channel microwave transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002001308A CA2001308A1 (en) | 1989-10-24 | 1989-10-24 | Short range multi-channel microwave transmitter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2001308A1 true CA2001308A1 (en) | 1991-04-24 |
Family
ID=4143382
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002001308A Abandoned CA2001308A1 (en) | 1989-10-24 | 1989-10-24 | Short range multi-channel microwave transmitter |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH03145829A (en) |
| CA (1) | CA2001308A1 (en) |
| IL (1) | IL96078A0 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109975856A (en) * | 2017-12-27 | 2019-07-05 | 核工业西南物理研究院 | A kind of multi-beam microwave source based on multiplexer |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11213051B2 (en) | 2014-07-02 | 2022-01-04 | Purina Animal Nutrition Llc | Milk replacer products containing halides and sources of hydrogen peroxide and methods of feeding same |
-
1989
- 1989-10-24 CA CA002001308A patent/CA2001308A1/en not_active Abandoned
-
1990
- 1990-01-19 JP JP2008576A patent/JPH03145829A/en active Pending
- 1990-10-22 IL IL96078A patent/IL96078A0/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109975856A (en) * | 2017-12-27 | 2019-07-05 | 核工业西南物理研究院 | A kind of multi-beam microwave source based on multiplexer |
| CN109975856B (en) * | 2017-12-27 | 2024-02-09 | 核工业西南物理研究院 | Multi-beam microwave source based on multiplexer |
Also Published As
| Publication number | Publication date |
|---|---|
| IL96078A0 (en) | 1991-07-18 |
| JPH03145829A (en) | 1991-06-21 |
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