CA2166556A1 - Microwave transmission system - Google Patents
Microwave transmission systemInfo
- Publication number
- CA2166556A1 CA2166556A1 CA002166556A CA2166556A CA2166556A1 CA 2166556 A1 CA2166556 A1 CA 2166556A1 CA 002166556 A CA002166556 A CA 002166556A CA 2166556 A CA2166556 A CA 2166556A CA 2166556 A1 CA2166556 A1 CA 2166556A1
- Authority
- CA
- Canada
- Prior art keywords
- input
- frequency
- microwave
- mixer
- signal
- 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
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D9/00—Demodulation or transference of modulation of modulated electromagnetic waves
- H03D9/06—Transference of modulation using distributed inductance and capacitance
- H03D9/0608—Transference of modulation using distributed inductance and capacitance by means of diodes
- H03D9/0633—Transference of modulation using distributed inductance and capacitance by means of diodes mounted on a stripline circuit
- H03D9/0641—Transference of modulation using distributed inductance and capacitance by means of diodes mounted on a stripline circuit located in a hollow waveguide
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D2200/00—Indexing scheme relating to details of demodulation or transference of modulation from one carrier to another covered by H03D
- H03D2200/0001—Circuit elements of demodulators
- H03D2200/0037—Diplexers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D2200/00—Indexing scheme relating to details of demodulation or transference of modulation from one carrier to another covered by H03D
- H03D2200/0041—Functional aspects of demodulators
- H03D2200/009—Reduction of local oscillator or RF leakage
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
- H03D7/14—Balanced arrangements
- H03D7/1408—Balanced arrangements with diodes
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
- H03D7/16—Multiple-frequency-changing
- H03D7/161—Multiple-frequency-changing all the frequency changers being connected in cascade
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
- H03D7/18—Modifications of frequency-changers for eliminating image frequencies
Abstract
In a microwave transmission system a microwave signal is transmitted by a transmitter (1) using an antenna (2) to a receiver (4) which employs an antenna (3). The received signal is coupled to a mixer (17) via a waveguide section (15) having a cut off frequency being higher than the frequency of the signal generated by the local oscillator unit (18). In this way, undesired emission of local oscillator signal is avoided. Furthermore no additional image rejection filter is required.
Description
WO 95131034 2 1 6 6 5 5 6 PCT/IBg5/00312 ~Microwave l~n~mi~sion system"
The invention is related to a microwave l.,.n~ inn system comrri~ing a rnicrowave tr~ncmittPr coupled to at least one microwave receiver via a tr~ncmi~inn link, an input of the rnicrowave receiver being coupled to a first input of a mixer via a t~ncmi~ion line, a local oscillator being coupled to a second input of the mil~er The invention is also related to a receiver and a frequency conversion unit for use in such a tr~n~mi~ciQn system.
A tr~n~mic~ion system according to the preamble is known from the book "Microwave devices" by M.J. Howes and D.V. Morgan, published by Wiley TntersriPn-~, ISBN 0 471 41729 7. pp. 344-345.
Recently two new frequency bands in the microwave range have been ~llQc~t~P~ for broadcast ~ul~s. These are the bands from 40.5 GHz - 42.5 GHz in CEPT ( Conference of Eufopean Post and Teleco"""l-nic~tiQn ~lmini~trations) countries and from 27.5 GHz - 29.5 GHz in other countries. There are several plans to use this frequency bands for distributing TV programs direct to the homes of the s~bscrihers. Also other microwave 15 frequencies can be used if they are made available for bro~dc~t ~ur~oses by the Authorities.
In the prior art system a microwave signal is tr~n~mitt~ by a tr~n.~mittf r, which microw~ve signal is received by a microwave receiver. The micl~wave receiver compri~es a mixer having one input coupled to an ~ntenn~ and having one input coupled to a local oscill~tor. The output of the mixer carrying an IF signal having a frequency of 750 20 MHz is coupled via a filter to a ~emodul~tor, for dem~--l~ting the received signal. With widespread use of such tpn~m~ on systems, care has to be taken to prevent the ~,en~ t;on of intelrt;fe, ce by such systems. One possible source of intt;lrer~nce is the r~ tion of the local osc-ill~tor signal. This local oscill~tor signal leaks via the mixer to the ~nlr~ where it is tr7~n~mitted into free space. In the prior art system a complex b~n~lp~ filter would be 25 required to prevent this undesired radiation.
The object of the present invention is to provide a microwave tr~n~mi~ion system in which the undesired r~ tion of the local oscillator is prevented in an easy and 2 1 ~ 6 2 ~
inr.~ ive way.
Therefor the invention is çh~ le-;~ in that the trancmi~ion line has a high pass transfer function with a predetermined cut off frequency and in that the frequency of the local osçill~tnr is lower than the predetell.lined cut off frequency.
By using a t~n~mi~ion line having a high pass transfer function and a local os~ tor frequency having a frequency below this cut off frequency, the local osc-ill~tor signal which leaks trough the mixer is strongly ~ A by the t~ncmiCcion line before the local osçill~tor signal reaches the ~n~
In every receiver using down conversion of the signal to be received by 10 mixing it with a local os~ tnr signal the frequency of the signal to be received can have the values ¦ fLo + fif ¦ and ¦ fLO-fif ¦, fLO being the local osc-ill~tor frequency and fif the interm~Ai~te frequency. If the frequency of the signal to be received is equal to ¦ fLo + fif ¦
(as it is in the ~n~mi~cion system according to the invention ) the so-called mirror frequency is equal to ¦ fLo-fif ¦ . It is cuslolll~y in the art that a so-call mirror su~.~i,ion 15 filter is present between the ~ntenn~ and the mixer. An ~ 1ition~1 advantage of the present invention is that no s~a-~te mirror su~r~ssion filter has to be added, because the mirror r~uency signal being lower in frequency than the local oscill~tor signal is effectively ~u~r~ssed by the t~n~mi~ion line having a high pass transfer fimcti~n.
An embodiment of the invention is c-h~r~çt~Pri~P~i in that the output of the 20 mixer is coupled to an input of a standard down converter having an input frequency in the range from 10-14 GHz.
The use of a standard down converter having an input frequency in the range from 10 to 14 GHz has the advantage that use can be made of down converters which are commonly used for domestic s~tçllit~ reception. These down converters are manufactured 25 in large qll~ntiti~s~ and can consequently be relatively cheap. Furthermore these standard downconverters have an eYc~ nt noise figure, resl-lting in a good noise figure for the complete receiver.
A further embo~imtont of the invention is çh~r~-~t~rised in that the trans-mission line comprises a waveguide.
A waveguide is an inexpensive type of tr~n~mi~ion line having a high pass transfer function. The cut off frequency can be set to the desired value by choosing suitable iim~n.~ions of the waveguide. The actual desired attenuation value of the local osç~ tor signal can be obtained by choosing a suitable length of the waveguide.
A further embodiment of the invention is char~cteri~od in that the receiver 216~5~
The invention is related to a microwave l.,.n~ inn system comrri~ing a rnicrowave tr~ncmittPr coupled to at least one microwave receiver via a tr~ncmi~inn link, an input of the rnicrowave receiver being coupled to a first input of a mixer via a t~ncmi~ion line, a local oscillator being coupled to a second input of the mil~er The invention is also related to a receiver and a frequency conversion unit for use in such a tr~n~mi~ciQn system.
A tr~n~mic~ion system according to the preamble is known from the book "Microwave devices" by M.J. Howes and D.V. Morgan, published by Wiley TntersriPn-~, ISBN 0 471 41729 7. pp. 344-345.
Recently two new frequency bands in the microwave range have been ~llQc~t~P~ for broadcast ~ul~s. These are the bands from 40.5 GHz - 42.5 GHz in CEPT ( Conference of Eufopean Post and Teleco"""l-nic~tiQn ~lmini~trations) countries and from 27.5 GHz - 29.5 GHz in other countries. There are several plans to use this frequency bands for distributing TV programs direct to the homes of the s~bscrihers. Also other microwave 15 frequencies can be used if they are made available for bro~dc~t ~ur~oses by the Authorities.
In the prior art system a microwave signal is tr~n~mitt~ by a tr~n.~mittf r, which microw~ve signal is received by a microwave receiver. The micl~wave receiver compri~es a mixer having one input coupled to an ~ntenn~ and having one input coupled to a local oscill~tor. The output of the mixer carrying an IF signal having a frequency of 750 20 MHz is coupled via a filter to a ~emodul~tor, for dem~--l~ting the received signal. With widespread use of such tpn~m~ on systems, care has to be taken to prevent the ~,en~ t;on of intelrt;fe, ce by such systems. One possible source of intt;lrer~nce is the r~ tion of the local osc-ill~tor signal. This local oscill~tor signal leaks via the mixer to the ~nlr~ where it is tr7~n~mitted into free space. In the prior art system a complex b~n~lp~ filter would be 25 required to prevent this undesired radiation.
The object of the present invention is to provide a microwave tr~n~mi~ion system in which the undesired r~ tion of the local oscillator is prevented in an easy and 2 1 ~ 6 2 ~
inr.~ ive way.
Therefor the invention is çh~ le-;~ in that the trancmi~ion line has a high pass transfer function with a predetermined cut off frequency and in that the frequency of the local osçill~tnr is lower than the predetell.lined cut off frequency.
By using a t~n~mi~ion line having a high pass transfer function and a local os~ tor frequency having a frequency below this cut off frequency, the local osc-ill~tor signal which leaks trough the mixer is strongly ~ A by the t~ncmiCcion line before the local osçill~tor signal reaches the ~n~
In every receiver using down conversion of the signal to be received by 10 mixing it with a local os~ tnr signal the frequency of the signal to be received can have the values ¦ fLo + fif ¦ and ¦ fLO-fif ¦, fLO being the local osc-ill~tor frequency and fif the interm~Ai~te frequency. If the frequency of the signal to be received is equal to ¦ fLo + fif ¦
(as it is in the ~n~mi~cion system according to the invention ) the so-called mirror frequency is equal to ¦ fLo-fif ¦ . It is cuslolll~y in the art that a so-call mirror su~.~i,ion 15 filter is present between the ~ntenn~ and the mixer. An ~ 1ition~1 advantage of the present invention is that no s~a-~te mirror su~r~ssion filter has to be added, because the mirror r~uency signal being lower in frequency than the local oscill~tor signal is effectively ~u~r~ssed by the t~n~mi~ion line having a high pass transfer fimcti~n.
An embodiment of the invention is c-h~r~çt~Pri~P~i in that the output of the 20 mixer is coupled to an input of a standard down converter having an input frequency in the range from 10-14 GHz.
The use of a standard down converter having an input frequency in the range from 10 to 14 GHz has the advantage that use can be made of down converters which are commonly used for domestic s~tçllit~ reception. These down converters are manufactured 25 in large qll~ntiti~s~ and can consequently be relatively cheap. Furthermore these standard downconverters have an eYc~ nt noise figure, resl-lting in a good noise figure for the complete receiver.
A further embo~imtont of the invention is çh~r~-~t~rised in that the trans-mission line comprises a waveguide.
A waveguide is an inexpensive type of tr~n~mi~ion line having a high pass transfer function. The cut off frequency can be set to the desired value by choosing suitable iim~n.~ions of the waveguide. The actual desired attenuation value of the local osç~ tor signal can be obtained by choosing a suitable length of the waveguide.
A further embodiment of the invention is char~cteri~od in that the receiver 216~5~
3'1 . 6. PCTIIB95/00312 comprises a reflector for refl~ting a received microwave to the input of the tr~n~mic~ior~
line, and in that the receiver comprising modifying means to modify the effective area of the reflector.
By using a refl~tor of which the effective area can be mo(1ifi~1 it is 5 possible to reduce the sensitivity of the receiver when a strong signal is received. This may be useful to prevent overload of the mixer which can cause intolerable distortion of the received signal.
The invention will now be described, by way of example, with reference to the drawings whelGin Fig. 1 a t~n~mi.~ion system according to the invention;
- Fig. 2 a block ~ ram of the receiver to be used in a tr~mmi~ion system according to the invention;
Fig. 3 an emb~iment of the mixer 17 according to Fig. 2;
Fig. 4 a second embo~im~-nt of the mixer 17 according to Fig. 2;
Fig. 5 a cross section of the mixer according to Fig. 4;
Fig. 6 A detail showing the connection of the mixer diodes 62 and 64 in Fig. S;
Fig. 7 an embo~liment of the outdoor unit 16.
In the tr~n~mi~ion system according to Fig. 1 a I~V signal to be tr~n~mitted is applied to the input of a tr~n~mitter 1. The TV signal, which can have an 25 analog format ( e.g. PAL, NTSC or SECAM ) or a digital format ( e.g. MPEG ) is modu-lated and upconverted to an R~ signal in the desired frequency band. This frequency band can be the band from 40.5 GHz - 42.5 GHz in CEPT countries and the band from 27.5 GHz - 29.5 GHz in other countlies. Also other microwave frequencies can be used if they are made available for broadcast p~,l,oses by the A~lthoriti~os The RF signal gencl~led by the tr~n~mitt~qr 1 is radiated by the ~r~t~nll~ 2. The ~n~ 2 can be a horn ~tlt~nl~, or can be a small parabolic reflector with co"Gs~nding feed.The signal tr~n~mitt~ by the ~n~ 1 is received by a number of recei-vers each present at a subscriber site to be provided with the TV signal. At each subscriber W O 95/31034 2 I 6 6 ~ 5 6 PCTAIB95/00312 site the signal tr~ncmitt~d by the tr~n~mit~r 1 is received by means of the coll~,sp~n~ing ~n~ n~ 3,6,9 or 12. The signal from the ~ e~n~ 3,6,9,12 iS pfu~ d by the coll~ 3n~ing receiver 4,7,10 or 12 to obtain a TV signal which is delivered to the collGs~nding TV set 5,8,11 or 14. It is observed that the use of a tr~n~mi~sion system according to Fig. 1 is not S limited to TV signals, but that it also can be used for other type of ~ign~l~, e.g. data signals.
In the receiver 4 accof~ing to Fig. 2 the input signal is coupled via the tr~n~mi~ion line being here a waveguide 15 to an input of an outdoor unit 16. the input of said outdoor unit 16 is formed by a first input of the mixer 17. An output of the local os~ tor unit 18 is coupled to a second input of the mixer 17. The local osc-ill~tor unit 18 compri~s a local oscillator 21 having an output coupled to an input of an amplifier 20. The output of the amplifier 20 iS couplP~d to the input of a tripler 18. The output of the tripler 18 con~tit~ltcs the output of the local oscill~tor unit 18.
The output of the mixer 17 iS coupled to an input of the down converter 22. The input of the down converter 22 iS coupled to an input of a low noise ~ m plifi~r 23.
The output of the low noise amplifier 23 iS coupled to a first input of a mixer 24. The output of an oscill~tor 35 is coupled to a second input of the mixer 24. The output of the mixer 24 is coupled to the input of an amplifier 25. The output of the ~ m plifiPr 25 con~ e~s the output of the outdoor unit 16. The outdoor unit 16 is coupl~ via a coaxial cable to the indoor unit 26, the output of which is co,~n~;led to the TV set.
The ~n~e~n~ signal is fed via the waveguide 15 to the mixer 17. The t~im~n~ions of the waveguide 15 are chosen to obtain a cut off r~ ency which is well above the r,~uen~r of the signal g~ncl~ted by the local oscillator unit 18. The length of the waveguide 15 is chosen to obtain sufficient suppression of the local osçill~tor signal. The standard down converter 22 iS commercially available from Philips Components under type Nos. SC 813 and SC 815. ~c~-lming an input frequency for the down converter 22 of 11.5 GHz and a reception band from 40.5 to 42.5 GHz the frequency from the local osc~ tor unit 18 must be adjustable from 29 GHz to 31 GHz.
To generate the local osç~ tor signal the local oscill~tQr 21 gçn..~s a signal in the 10 GHz range. This signal is amplified by means of the amplifier 20 to a 30 snfficient level. The output signal of the amplifier 20 iS multiplied in frequency with a factor three by the tripler 19 so that a signal having the desired frequency is available at the second input of the mixer 17. The tripler 19 can be build using a varactor diode mounted in a waveguide. A suitable varactor diode is commercially available from Philips Components under type No. CXY 12/381073.
216~5~i6 The output signal from the mixer 17 is amplified by the low noise amplifia 23 of the down converter 22. The output signal of the low noise ~mplifier is converted to a frequency in the range from 0.95 GHz to 1.7 GHz by mixing a 10 GHz signal from the osç~ tor 35 with the output signal of the low noise ~mplifiPr 24 by means of the S mi~cer 24. The output signal of the mixer 24 is ~mplifi~ by the ~mplifiP,r 25 and tr~n~mittP~l to the indoor unit 26. The indoor unit 26 converts the signal lGceiv~d from the outdoor unit 16 into a signal which is suitable for a ;u~L(lIll~y TV set. The indoor unit is of the type used for the reception of direct broadcast ~t~llites and is co~ --c.cially available from Philips Cbn~l~mPr ElecLronics.
In the mixer 17 according to Fig. 3 the received signal is applied to the waveguide section 27. The ~iimPncions of said waveguide section are chosen to obtain a cut off frequency above the frequency of the loc,al os~ tor. The relation between cut off frequency and ~limPn~innc of the waveguide is well known to those skilled in the art, and is e.g. des~ilibad in the book "Microwave e .-gin~ ;i-g" by A.F. Harvey published by ~C~llpmic 15 Press Inc. 1963 section 1.4 pp. 11-14. The length of the waveguide section 27 to obtain a desired atlenualion of the local oscill~tor signal c,an also easily delel-"ined from the eA~ressions ~ese,l~ed in the above mentioned book.
The output of the waveguide section 27 is guided via a tr~n~ition section 28 to a waveguide section 31 large enough to conduct the IF signals having a frequency of 20 a~luAimately 11.5 GHz. Fu~lh~ ore the output signal of the loc,al oscill~tor unit 18 is coupled into the waveguide section 31 via the waveguide section 29 and the transition section 30. In the waveguide section 31 the electric fields from the input signal and the local oscill~tor signal are added. Due to the non-linear transfer char~tPrictics of the diode 32 an IF signal having the desired frequency is generated, and is available at the output of the 25 waveguide section 31.
In the mixer 17 according to Fig. 4 a carrier 52 is introduced in the waveguide 50. This carrier is positioned in parallel with the E-plane of the field in the waveguide 50.
In the cross section according to Fig. S of the mixer 17 according to Fig.
30 4 the RF signal enters the mixer in taper 52 which transforms the received signal into a signal which is carried by the fin line waveguide 54. The part 63 forms an i~ cetran~r~l",ation section which adapts the h~ c,e of the waveguide 50 to the i"~ ee needed for the mixing diodes 62 and 64. At the mixing diodes 62 and 64 the received signal is split in two equal parts being in phase.
WO 95131034 2 1 ~ 6 ~ ~ 6 PCT/IB95/00312 The local oscill~tQr signal is applied via the strirline 56 to the mixer. This local osrill~tnr is t~n~fPrred via the high-pass filter 65 to the strirlinP, 57. The signal carAed by the striplin~ 57 is transformed into two signals being in anti-phase, being carried by the fin line waveguides 58 and 59. The signal which is carAed by the fin line waveguide 58 is 5 applied to the mixer diode 62, and the signal carAed by the fin line waveguide 60 is applied to the mixer diode 64.
The mixer diodes are connP~ct~ in seAes, and are biased with a DC
current of 1 mA. Suitable diodes are gallium arsenide Mott diodes of the CAY 18 or CAY
19 type. The IF signal is available at the stApline 56, and is tapped of via the low pass filter 10 60. The high pass filter 65 is formed by a Z formed spacing which is made in the stripline 56.
In fig. 6 it is shown that the mixer diodes 62 and 64 are connPcte~ in series bGlween the con~lucting planes. The junction bc;~ween the two mixer diodes 62 and 64 is connPcted to the striI)linp 57 for tapping off the IF signal.
In the receiver arrangement according to Fig. 7 a horn ~n~nn~ 25 iS
~tt~hP~l to the input of the mixer 17 via the waveguide section 15. Above the horn ~ntenl-~25 a parabolic reflector 3 is mounted. The parabolic reflector 3 can be slid partial into the 20 box 40, enabling the adaption of the effective area of said parabolic reflector 3. In this way the strength of the received signal level can be adjusted to avoid overload of the mixer 17 when a signal from a very near tr~n~mitter is received. In this way the application of passive Ol~ can be avoided.
line, and in that the receiver comprising modifying means to modify the effective area of the reflector.
By using a refl~tor of which the effective area can be mo(1ifi~1 it is 5 possible to reduce the sensitivity of the receiver when a strong signal is received. This may be useful to prevent overload of the mixer which can cause intolerable distortion of the received signal.
The invention will now be described, by way of example, with reference to the drawings whelGin Fig. 1 a t~n~mi.~ion system according to the invention;
- Fig. 2 a block ~ ram of the receiver to be used in a tr~mmi~ion system according to the invention;
Fig. 3 an emb~iment of the mixer 17 according to Fig. 2;
Fig. 4 a second embo~im~-nt of the mixer 17 according to Fig. 2;
Fig. 5 a cross section of the mixer according to Fig. 4;
Fig. 6 A detail showing the connection of the mixer diodes 62 and 64 in Fig. S;
Fig. 7 an embo~liment of the outdoor unit 16.
In the tr~n~mi~ion system according to Fig. 1 a I~V signal to be tr~n~mitted is applied to the input of a tr~n~mitter 1. The TV signal, which can have an 25 analog format ( e.g. PAL, NTSC or SECAM ) or a digital format ( e.g. MPEG ) is modu-lated and upconverted to an R~ signal in the desired frequency band. This frequency band can be the band from 40.5 GHz - 42.5 GHz in CEPT countries and the band from 27.5 GHz - 29.5 GHz in other countlies. Also other microwave frequencies can be used if they are made available for broadcast p~,l,oses by the A~lthoriti~os The RF signal gencl~led by the tr~n~mitt~qr 1 is radiated by the ~r~t~nll~ 2. The ~n~ 2 can be a horn ~tlt~nl~, or can be a small parabolic reflector with co"Gs~nding feed.The signal tr~n~mitt~ by the ~n~ 1 is received by a number of recei-vers each present at a subscriber site to be provided with the TV signal. At each subscriber W O 95/31034 2 I 6 6 ~ 5 6 PCTAIB95/00312 site the signal tr~ncmitt~d by the tr~n~mit~r 1 is received by means of the coll~,sp~n~ing ~n~ n~ 3,6,9 or 12. The signal from the ~ e~n~ 3,6,9,12 iS pfu~ d by the coll~ 3n~ing receiver 4,7,10 or 12 to obtain a TV signal which is delivered to the collGs~nding TV set 5,8,11 or 14. It is observed that the use of a tr~n~mi~sion system according to Fig. 1 is not S limited to TV signals, but that it also can be used for other type of ~ign~l~, e.g. data signals.
In the receiver 4 accof~ing to Fig. 2 the input signal is coupled via the tr~n~mi~ion line being here a waveguide 15 to an input of an outdoor unit 16. the input of said outdoor unit 16 is formed by a first input of the mixer 17. An output of the local os~ tor unit 18 is coupled to a second input of the mixer 17. The local osc-ill~tor unit 18 compri~s a local oscillator 21 having an output coupled to an input of an amplifier 20. The output of the amplifier 20 iS couplP~d to the input of a tripler 18. The output of the tripler 18 con~tit~ltcs the output of the local oscill~tor unit 18.
The output of the mixer 17 iS coupled to an input of the down converter 22. The input of the down converter 22 iS coupled to an input of a low noise ~ m plifi~r 23.
The output of the low noise amplifier 23 iS coupled to a first input of a mixer 24. The output of an oscill~tor 35 is coupled to a second input of the mixer 24. The output of the mixer 24 is coupled to the input of an amplifier 25. The output of the ~ m plifiPr 25 con~ e~s the output of the outdoor unit 16. The outdoor unit 16 is coupl~ via a coaxial cable to the indoor unit 26, the output of which is co,~n~;led to the TV set.
The ~n~e~n~ signal is fed via the waveguide 15 to the mixer 17. The t~im~n~ions of the waveguide 15 are chosen to obtain a cut off r~ ency which is well above the r,~uen~r of the signal g~ncl~ted by the local oscillator unit 18. The length of the waveguide 15 is chosen to obtain sufficient suppression of the local osçill~tor signal. The standard down converter 22 iS commercially available from Philips Components under type Nos. SC 813 and SC 815. ~c~-lming an input frequency for the down converter 22 of 11.5 GHz and a reception band from 40.5 to 42.5 GHz the frequency from the local osc~ tor unit 18 must be adjustable from 29 GHz to 31 GHz.
To generate the local osç~ tor signal the local oscill~tQr 21 gçn..~s a signal in the 10 GHz range. This signal is amplified by means of the amplifier 20 to a 30 snfficient level. The output signal of the amplifier 20 iS multiplied in frequency with a factor three by the tripler 19 so that a signal having the desired frequency is available at the second input of the mixer 17. The tripler 19 can be build using a varactor diode mounted in a waveguide. A suitable varactor diode is commercially available from Philips Components under type No. CXY 12/381073.
216~5~i6 The output signal from the mixer 17 is amplified by the low noise amplifia 23 of the down converter 22. The output signal of the low noise ~mplifier is converted to a frequency in the range from 0.95 GHz to 1.7 GHz by mixing a 10 GHz signal from the osç~ tor 35 with the output signal of the low noise ~mplifiPr 24 by means of the S mi~cer 24. The output signal of the mixer 24 is ~mplifi~ by the ~mplifiP,r 25 and tr~n~mittP~l to the indoor unit 26. The indoor unit 26 converts the signal lGceiv~d from the outdoor unit 16 into a signal which is suitable for a ;u~L(lIll~y TV set. The indoor unit is of the type used for the reception of direct broadcast ~t~llites and is co~ --c.cially available from Philips Cbn~l~mPr ElecLronics.
In the mixer 17 according to Fig. 3 the received signal is applied to the waveguide section 27. The ~iimPncions of said waveguide section are chosen to obtain a cut off frequency above the frequency of the loc,al os~ tor. The relation between cut off frequency and ~limPn~innc of the waveguide is well known to those skilled in the art, and is e.g. des~ilibad in the book "Microwave e .-gin~ ;i-g" by A.F. Harvey published by ~C~llpmic 15 Press Inc. 1963 section 1.4 pp. 11-14. The length of the waveguide section 27 to obtain a desired atlenualion of the local oscill~tor signal c,an also easily delel-"ined from the eA~ressions ~ese,l~ed in the above mentioned book.
The output of the waveguide section 27 is guided via a tr~n~ition section 28 to a waveguide section 31 large enough to conduct the IF signals having a frequency of 20 a~luAimately 11.5 GHz. Fu~lh~ ore the output signal of the loc,al oscill~tor unit 18 is coupled into the waveguide section 31 via the waveguide section 29 and the transition section 30. In the waveguide section 31 the electric fields from the input signal and the local oscill~tor signal are added. Due to the non-linear transfer char~tPrictics of the diode 32 an IF signal having the desired frequency is generated, and is available at the output of the 25 waveguide section 31.
In the mixer 17 according to Fig. 4 a carrier 52 is introduced in the waveguide 50. This carrier is positioned in parallel with the E-plane of the field in the waveguide 50.
In the cross section according to Fig. S of the mixer 17 according to Fig.
30 4 the RF signal enters the mixer in taper 52 which transforms the received signal into a signal which is carried by the fin line waveguide 54. The part 63 forms an i~ cetran~r~l",ation section which adapts the h~ c,e of the waveguide 50 to the i"~ ee needed for the mixing diodes 62 and 64. At the mixing diodes 62 and 64 the received signal is split in two equal parts being in phase.
WO 95131034 2 1 ~ 6 ~ ~ 6 PCT/IB95/00312 The local oscill~tQr signal is applied via the strirline 56 to the mixer. This local osrill~tnr is t~n~fPrred via the high-pass filter 65 to the strirlinP, 57. The signal carAed by the striplin~ 57 is transformed into two signals being in anti-phase, being carried by the fin line waveguides 58 and 59. The signal which is carAed by the fin line waveguide 58 is 5 applied to the mixer diode 62, and the signal carAed by the fin line waveguide 60 is applied to the mixer diode 64.
The mixer diodes are connP~ct~ in seAes, and are biased with a DC
current of 1 mA. Suitable diodes are gallium arsenide Mott diodes of the CAY 18 or CAY
19 type. The IF signal is available at the stApline 56, and is tapped of via the low pass filter 10 60. The high pass filter 65 is formed by a Z formed spacing which is made in the stripline 56.
In fig. 6 it is shown that the mixer diodes 62 and 64 are connPcte~ in series bGlween the con~lucting planes. The junction bc;~ween the two mixer diodes 62 and 64 is connPcted to the striI)linp 57 for tapping off the IF signal.
In the receiver arrangement according to Fig. 7 a horn ~n~nn~ 25 iS
~tt~hP~l to the input of the mixer 17 via the waveguide section 15. Above the horn ~ntenl-~25 a parabolic reflector 3 is mounted. The parabolic reflector 3 can be slid partial into the 20 box 40, enabling the adaption of the effective area of said parabolic reflector 3. In this way the strength of the received signal level can be adjusted to avoid overload of the mixer 17 when a signal from a very near tr~n~mitter is received. In this way the application of passive Ol~ can be avoided.
Claims (11)
1. Microwave transmission system comprising a microwave transmitter (1) coupled to at least one microwave receiver (4) via a transmission link, an input of the microwave receiver (4) being coupled to a first input of a mixer (17) via a transmission line (15), a local oscillator (18) being coupled to a second input of the mixer (17), characterised in that the transmission line (15) has a high pass transfer function with a predetermined cut off frequency and in that the frequency of the local oscillator (18) is lower than the predeter-mined cut off frequency.
2. Microwave transmission system according to claim 1, characterised in that the output of the mixer (17) is coupled to an input of a standard down converter (22) having an input frequency in the range from 10-14 GHz.
3. Microwave transmission system according to claim 1 or 2 characterised in that the transmission line (15) comprises a waveguide.
4. Microwave transmission system according to one of the previous claims, characterised in that the receiver comprises a reflector (3) for reflecting a received microwave to the input of the transmission line (15), and in that the receiver comprising modifying means (40) to modify the effective area of the reflector.
5. Microwave transmission system according to claim 4, characterised in that the reflector (3) has a parabolic shape.
6. Microwave receiver (4) having an input coupled to a first input of a mixer (17) via a transmission line (15), a local oscillator (18) being coupled to a second input of the mixer (17), characterised in that the transmission line (15) has a high pass transfer function with a predetermined cut off frequency and in that the frequency of the local oscillator (18) is lower than the predetermined cut off frequency.
7. Microwave receiver according to claim 6, characterised in that the output of the mixer (17) is coupled to an input of a standard down converter (22) having an input frequency in the range from 10-14 GHz.
8. Microwave receiver according to claim 6 or 7 characterised in that the transmission line (15) comprises a waveguide.
9. Microwave receiver according to one of the claims 6 to 8, characterised in that the receiver comprises a reflector (3) for reflecting a received microwave to the input of the transmission line (15), and in that the receiver (4) comprising modifying means (40) to modify the effective area of the reflector.
10. Microwave receiver according to claim 9, characterised in that thereflector (3) has a parabolic shape.
11. Microwave frequency conversion unit (17,18) having an input coupled to a first input of a mixer (17) via a transmission line (15), a local oscillator (18) being coupled to a second input of the mixer (17), characterised in that the transmission line (15) has a high pass transfer function with a predetermined cut off frequency and in that the frequency of the local oscillator (18) is lower than the predetermined cut off frequency.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP94201250 | 1994-05-06 | ||
| EP94201250.1 | 1994-05-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2166556A1 true CA2166556A1 (en) | 1995-11-16 |
Family
ID=8216848
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002166556A Abandoned CA2166556A1 (en) | 1994-05-06 | 1995-05-04 | Microwave transmission system |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5953644A (en) |
| EP (1) | EP0707757B1 (en) |
| JP (1) | JPH08512448A (en) |
| AU (1) | AU690980B2 (en) |
| CA (1) | CA2166556A1 (en) |
| DE (1) | DE69514191T2 (en) |
| WO (1) | WO1995031034A2 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2747840B1 (en) * | 1996-04-22 | 1998-09-11 | Motorola Semiconducteurs | IRRADIATION APPARATUS COMBINED BY AN ION BEAM AND MICROWAVE RADIATION, AND ASSOCIATED PROCESS |
| IT1284025B1 (en) * | 1996-06-18 | 1998-05-08 | Italtel Spa | FREQUENCY CONVERTER FOR APPLICATIONS TO MILLIMETRIC RADIO WAVES |
| GB0000079D0 (en) * | 2000-01-05 | 2000-02-23 | Ferring Bv | Novel antidiuretic agents |
| US6683513B2 (en) | 2000-10-26 | 2004-01-27 | Paratek Microwave, Inc. | Electronically tunable RF diplexers tuned by tunable capacitors |
| US7072649B2 (en) * | 2001-11-06 | 2006-07-04 | Volvo Trucks North America, Inc. | Multiple purpose antenna system |
| GB0207370D0 (en) * | 2002-03-28 | 2002-05-08 | Univ St Andrews | Medical imaging apparatus |
| CN109155611B (en) * | 2016-06-06 | 2020-10-27 | 华为技术有限公司 | Method and device for inhibiting local oscillator leakage in microwave chip |
Family Cites Families (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3696432A (en) * | 1971-01-15 | 1972-10-03 | Motorola Inc | Combined scan and track antennas |
| DE2847486A1 (en) * | 1978-11-02 | 1980-05-14 | Bayer Ag | USE OF METALIZED TEXTILES AS A RADIATION PROTECTION AGAINST MICROWAVES |
| DE2925827B2 (en) * | 1979-06-27 | 1981-07-09 | Siemens AG, 1000 Berlin und 8000 München | Microwave and millimeter wave mixers |
| US4460897A (en) * | 1981-04-02 | 1984-07-17 | Bell Telephone Laboratories, Incorporated | Scanning phased array antenna system |
| US4380829A (en) * | 1981-05-18 | 1983-04-19 | Varian Associates, Inc. | Simplified double balanced frequency converter |
| JPS583404A (en) * | 1981-06-30 | 1983-01-10 | Toshiba Corp | Frequency converting circuit |
| US4411022A (en) * | 1982-01-27 | 1983-10-18 | The United States Of America As Represented By The Secretary Of The Air Force | Integrated circuit mixer apparatus |
| US4418429A (en) * | 1982-05-07 | 1983-11-29 | General Electric Company | Mixer for use in a microwave system |
| WO1984003008A1 (en) * | 1983-01-20 | 1984-08-02 | Matsushita Electric Ind Co Ltd | Frequency converter |
| JPS60245318A (en) * | 1984-05-18 | 1985-12-05 | Sharp Corp | Waveguide type image suppressing mixer |
| CA1262773A (en) * | 1985-12-25 | 1989-11-07 | Mitsuhiro Kusano | Horn antenna with a choke surface-wave structure on the outer surface thereof |
| US4996535A (en) * | 1988-09-08 | 1991-02-26 | General Electric Company | Shortened dual-mode horn antenna |
| JPH042202A (en) * | 1990-04-19 | 1992-01-07 | Sumitomo Electric Ind Ltd | Microwave device |
| US5125110A (en) * | 1990-10-17 | 1992-06-23 | Valentine Research, Inc. | Microstripline microwave mixer using waveguide filter |
| USH1034H (en) * | 1990-12-28 | 1992-03-03 | United States Of America | Millimeter wave tracking radar antenna with variable azimuth pattern |
| DE69419944T2 (en) * | 1993-01-13 | 1999-12-02 | Honda Motor Co Ltd | Dielectric waveguide mixer and radar module with dielectric waveguide |
| US5305007A (en) * | 1993-04-13 | 1994-04-19 | Cincinnati Microwave Corporation | Wideband radar detector |
| US5396658A (en) * | 1993-06-14 | 1995-03-07 | University Of Utah Research Foundation | Radio frequency antenna and mixer array |
-
1995
- 1995-05-04 JP JP7528812A patent/JPH08512448A/en not_active Ceased
- 1995-05-04 CA CA002166556A patent/CA2166556A1/en not_active Abandoned
- 1995-05-04 WO PCT/IB1995/000312 patent/WO1995031034A2/en active IP Right Grant
- 1995-05-04 DE DE69514191T patent/DE69514191T2/en not_active Expired - Fee Related
- 1995-05-04 EP EP95915967A patent/EP0707757B1/en not_active Expired - Lifetime
- 1995-05-04 AU AU22652/95A patent/AU690980B2/en not_active Ceased
-
1997
- 1997-07-28 US US08/901,339 patent/US5953644A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| AU2265295A (en) | 1995-11-29 |
| WO1995031034A2 (en) | 1995-11-16 |
| JPH08512448A (en) | 1996-12-24 |
| DE69514191D1 (en) | 2000-02-03 |
| AU690980B2 (en) | 1998-05-07 |
| DE69514191T2 (en) | 2000-08-17 |
| EP0707757A1 (en) | 1996-04-24 |
| EP0707757B1 (en) | 1999-12-29 |
| US5953644A (en) | 1999-09-14 |
| WO1995031034A3 (en) | 1996-01-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |