GB2358533A - Antenna; feed; alarm sensor - Google Patents
Antenna; feed; alarm sensor Download PDFInfo
- Publication number
- GB2358533A GB2358533A GB0001458A GB0001458A GB2358533A GB 2358533 A GB2358533 A GB 2358533A GB 0001458 A GB0001458 A GB 0001458A GB 0001458 A GB0001458 A GB 0001458A GB 2358533 A GB2358533 A GB 2358533A
- Authority
- GB
- United Kingdom
- Prior art keywords
- antenna
- oscillator
- alarm sensor
- temperature
- circuit
- 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.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
- H01Q21/061—Two dimensional planar arrays
- H01Q21/065—Patch antenna array
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
- H01Q9/04—Resonant antennas
- H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
- H01Q9/04—Resonant antennas
- H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
- H01Q9/0421—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with a shorting wall or a shorting pin at one end of the element
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
- H01Q9/04—Resonant antennas
- H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
- H01Q9/045—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with particular feeding means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/50—Systems of measurement based on relative movement of target
- G01S13/52—Discriminating between fixed and moving objects or between objects moving at different speeds
- G01S13/56—Discriminating between fixed and moving objects or between objects moving at different speeds for presence detection
Abstract
Two patch antennas 11, 12 operating at a frequency . g. , have an electrical length of n. g. 12, and are grounded at a position 18, 19 which is at an electrical distance equal to one quarter of the wavelength of signals having a frequency of interest from one end. At the frequency of interest, a null is present at the grounding position 18, 19, so no attenuation occurs. At other, undesired, frequencies no null is present, and attenuation of signals occurs. A one-quarter wavelength stub 20 is grounded at one end 21 and connected to a feed 16 at the other end. An alarm sensor (Figure 4) has an oscillator and a mixer which have respective semiconductor devices. The alarm sensor also has compensation for temperature-dependent changes in sensitivity.
Description
2358533 0:\SPECSPSD\44595.1wp AN ANTENNA ARRANGEMENT This invention
relates to an antenna arrangement, and in particular, although not exclusively, to an antenna arrangement suitable for use with a microwave frequency Doppler alarm sensor.
It is known to use patch antennas to transmit and receive microwave frequency signals in, for example, Doppler intruder alarm sensors. One example is shown in GB-A2322029. One or more dimensions of an antenna is/are selected to correspond to an integer half wavelength of the signals of interest. For example, a 2.45 GHz alarm sensor will often involve one or more rectangular patch antennas formed on one side of a high dielectric substrate, and with a conducting ground plane formed on the other side of the substrate. The or each patch antenna has one side having a length of around 4 cm. The dielectric properties of the substrate allow the antennas to adopt such small dimensions, whereas an equivalent antenna in free space would have a length of about 6.1 cm. With dimensions corresponding to an integer multiple of the half wavelength, the antennas resonate at the frequency of interest, and sensitivity is at a maximum at that frequency. However, the antennas are also sensitive to signals at other frequencies, albeit with reduced receive efficiency. Where an interfering radiation source operates with sufficiently high power, the interfering signals may swamp the signals of interest, and the integrity of the alarm sensor may be prejudiced.
According to this invention, an antenna arrangement comprises an antenna having a length corresponding substantially to an integer multiple of the half wavelength of a frequency of signals of interest, the antenna being grounded at a distance from an end of its length corresponding substantially to one quarter of the wavelength of the frequency of interest. Preferably the antenna is a patch antenna.
2 yl s All types of antenna are sensitive, to some degree, to signals other than those sil, having desired frequencies. Reducing the sensitivity of an antenna arrangemeni '0 non-desired signal frequencies is desirable.
According to another aspect of this invention, an antenna arrangement compnsesj'. MI antenna, a feed connected to the antenna, and a stub having a length corresponju substantially to an odd integer multiple of one quarter of the wavelength of a desAr( signal frequency, the stub being connected to the feed at one end and being grounded the other end.
These aspects of the invention will now be described, by way of example only, Vvi ji reference to Figures I and 2, each of which shows a plan view of an antem A arrangement according to one or more aspects of the invention.
Referring to Figure 1, an antenna arrangement 10 comprises first and secipAd rectangular patch antennas 11 and 12 each connected to a power divider 13 by.; 3. respective connecting arm 14 and 15. The connecting arms 14 and 15 each constitute a 50 f2 transmission line. The power divider 13 is connected to an alarm sensor ci. it (not shown) by a feed 16. The antennas 11 and 12 are formed on an upper side (f a substrate 17, and a ground plane (not shown) is formed over the whole of the underlit-, of the substrate. The patch antennas 11 and 12 are edge fed by their respee.jive connecting arms 14 and 15.
The antennas 11 and 12 each have a longer side x of length 3 cm, and a shorter side y f j length 2 cm. The length of each side x corresponds to half the wavelength of a Z,.+5 GHz frequency signal, since the substrate 17 has a high dielectric constant (4.0. f example). The length of each side y is chosen to avoid spurious modes.
The antennas 11 and 12 are each connected to the ground plane by a respecti: re through-substrate via 18 and 19 which is located at the geometric centre of! ts respective antenna. The through-substrate vias 18 and 19 connect the antennas I I. M k I 12 to ground at a distance from each end of the length of the side x which correspoin s 3 to one quarter of the wavelength of the frequency of interest, i.e. 2. 45 GHz. Received signals at or around 2.45 GHz are substantially unaffected by the grounding of the antennas, since there is a signal null at the position of the vias 18 and 19. However, any received signal having a different wavelength is unlikely to be resonant along the length of the side x, and there is no signal null at the centre of the antennas 11 and 12 for these signals. These signals are attenuated by the grounding, and are therefore less likely to interfere with the correct operation of the alarm sensor.
In another embodiment (not shown) a patch antenna has a side having a length corresponding to one whole wavelength of the frequency of signals of interest. Two through-substrate vias connect the antenna to ground, one via being one quarter of the wavelength along the length of the antenna, and the other via being three-quarters of the wavelength along the length of the antenna. Received signals having substantially the frequency of interest produce nulls at the via positions, so are not affected by the antenna grounding. Signals at other frequencies are grounded.
Referring to Figure 2, an antenna arrangement 30 is shown, with reference numerals retained from Figure 1 for like elements. The antenna arrangement 30 includes a onequarter wavelength stub 20 connected to the feed 16. The stub 20 is connected to the ground plane (not shown) by a through-substrate via 21 at its end remote from the feed 16.
The quarter wavelength stub 20 acts as an impedance transformer at the desired frequency. At this frequency, a short circuit at one end of the stub 20 is transformed to an open circuit at the opposite end. The grounded end of the stub 20 is transformed to an open circuit at the connection of the stub and the feed 16, resulting in no attenuation of signals at the desired frequency. Signals at other frequencies are, however, grounded by the via 21 and the ground plane (not shown). It will be appreciated that the stub 20 can be connected at any position on the feed 16, and that more than one stub can be used to increase rejection of signals at unwanted frequencies.
4 In another embodiment (not shown) a stub having a length corresponding to 0" e quarters of the wavelength of the desired frequency is connected to the feed. The sf'u ie effect is achieved, although this embodiment requires more board area. The end of te stub remote from the feed is grounded by edge metalisation of the substrate bom (1, 5 instead of by a through substrate via to a ground plane.
Alarm sensors such as that described in GB-A-2322029 traditionally use a si#. E le transistor arranged to function both as an oscillator and as a mixer of the transrnitt signal with the received signal. A typical arrangement is shown in Figure 3. 10 Referring to Figure 3, an alarm sensor 40 is shown comprising generally first Pj second patch antennas 41 and 42, which are connected together and to a sensor cir0h arrangement by a power divider formed by resistors 4345. The sensor cirpd I arrangement includes an npn bipolar transistor 46, having its emitter connected to:
power divider by a dc blocking capacitor 47. The non-linearity of the transistor, 1) base-emitter junction provides the mixing function, the baseband signal being presert the emitter. The collector and the base of the transistor 46 are biased extern8 d L, I- Trimming of the frequency of operation of the alarm sensor is achieved by varying I i 1 capacitance of a ftirther capacitor 50. The oscillator frequency is stabilised by a 20 ceramic resonator 48.
The transistor is biased to have an emitter current of approximately 2 mA, to optil e oscillator performance and thereby provide good stability of the transmitted sio Stability is important particularly where the alarm sensor 40 is required to operate in;I 25 narrow frequency band, such as the 2.45 GHz ISM band.
According to another aspect of the invention, there is provided an alarm se s comprising an oscillator arranged to provide output signals to an antenna, and a mix 1. arranged to mix the oscillator output signals with signals received by the or ano,h 30 antenna, the oscillator and the mixer each having a respective semiconductor device.
Using this invention, it is possible to increase the sensitivity of an alarm sensor, compared to the equivalent alarm sensor using a common oscillator and mixer transistor, since the oscillator semiconductor device and the mixer semiconductor device can be independently biased. This allows the biasing of the mixer semiconductor device to be optimised for mixing, thereby increasing the sensitivity of the alarm sensor.
The inventors have discovered that the Figure 3 alarm sensor 40 has a sensitivity characteristic which decreases with increasing temperature. Analysis has shown that this is a result of the oscillator output power decreasing with increasing temperature.
This results from the gain of the transistor 46 changing with changing temperature. The effects of the change in sensitivity is not great over an operating temperature range, such as -40 'C to +95 T, but the effect is significant.
In accordance with another aspect of this invention, there is provided an alarm sensor comprising an antenna, an oscillator, a mixer, a sensor circuit, and a temperature compensation circuit arranged to compensate at least in part for temperature-dependent changes in sensitivity.
The temperature compensation circuit may be associated with the sensor circuit, or it may be associated with the mixer. Preferably, however, the temperature compensation circuit is associated with the oscillator. More preferably, the temperature compensation circuit is arranged to vary the bias current of a transistor forming part of the oscillator with varying temperature.
These inventions will now be described, by way of example only, with reference to Figure 4, which shows part of an alarm sensor constructed in accordance with the invention. Reference numerals are retained from Figure 3 for like elements.
Referring to Figure 4, an alarm sensor 50 comprises an oscillator 51, based around an oscillator transistor 52, a mixer or detector 53, and a temperature compensation circuit 54.
6 The oscillator transistor 52 is biased with a current of 3 niA, which is optimunq i or oscillator performance, by appropriate resistors 60 and 61 at its base and its emittex. A' transistor 5 5, forming the core of the mixer 53, is biased with a current of 1 mA, so uit the transistor 55 operates in a non-linear region, by appropriate resistors 62 and 63 tt i is base and its emitter. The transistor 55 is coupled to the antennas 41 and 4.2i y capacitors 56 and 47. Operating the transistor 55 with a bias current optimisedl or mixing allows improved sensitivity without any compromise of the performance oli 1 e oscillator 5 1.
A diode (not shown) may be used in place of the transistor 55. The use of a diode; ILS the advantage.of smaller size and lower cost compared to a transistor. Diode bia i 9 may be necessary to provide optimum conversion efficiency.
The temperature compensation circuit 54 comprises a thermistor 57 connecte,4 10 ground on one side by a first resistor 56, and connected to the emitter of a series S regulator transistor 64 on the other side by a second resistor 58. A third resistor 9.1s connected across the thermistor 57. The node connecting the thermistor 57 with 1,,e first resistor 56 is connected to the base of the oscillator transistor 52 by a fbi: 1h resistor 60. The transistor 64 regulates the collector bias for the transistors 52 and.55.
The effect of the temperature compensation circuit 54 is to vary the emitter curre,t f the oscillator transistor 52 so that the output power of the alarm sensor 50 rein! is substantially constant with temperature. This is achieved by increasing the base hh &S voltage of the transistor 52 as the temperature increases, since the voltage at the 4c,,ie connecting the thermistor 57 with the resistor 56 is temperature dependent, thef e y 1 1 causing the oscillator 51 output power to be maintained at a substantially constant ICIIIIAL Alternatively, the gain of baseband amplifier stages feeding the threshold input a 30 comparator (not shown) in the sensor circuitry (not shown) is decreased with increasi g temperature. This adjustment results in substantially constant sensitivity v.l,,,h temperature if the gain adjustment per unit temperature is correctly selected. HowdAr, 7 the oscillator bias current compensation is preferred, since it is simple and inexpensive to implement.
With either embodiment, an active transistor-based, temperature compensation circuit could be used in place of the passive temperature compensation circuit 54. Such an active temperature compensation circuit could be implemented in an ASIC.
Forming patch antennas onto circuit boards is usually advantageous in terms of a saving in the number of individual components that make up an alarm sensor, or any other device incorporating patch antennas. However, since it is usual for an antenna to be associated with a metalised ground plane on the opposite side of the circuit board, the incorporation of patch antennas can take up a significant area of the board. There is a continuing drive to reduce the size of circuit boards in such devices.
According to another aspect of the invention, there is provided an antenna arrangement comprising a patch antenna and a circuit board, the circuit board having first and second sides, circuitry, a ground plane and a feed being provided on the first side, and a launcher being provided on the second side, a through-board via connecting the feed to the launcher, and the patch antenna being spaced from the launcher.
This aspect of the invention is now described, by way of example only, with reference to Figures 5A and 5B which show plan views of second and first sides respectively of a circuit board forming part of the invention, and with reference to Figure 6, which shows, in cross-section, the circuit board of Figures 5A and 513 installed in an antenna arrangement constructed in accordance with this invention.
Referring to Figure 5A, a circuit board 70 has a metalised launcher 72 and a substantially rectangular ground plane 73 on its second side 71. The launcher 72 is 6 mm wide and 20 mm long, the length being substantially equal to one quarter of the wavelength of a 2.45 GHz ISM signal, since the circuit board 70 has a relatively high dielectric constant, for example 3.0. The launcher 72 is separated from the ground plane 73 by a gap which is small compared to the wavelength of the 2.45 GHz signal. The 8 launcher 72 has, at one end, first and second through-board or through- substrate vias 74 and 75. These vias 74 and 75 connect the launcher 72 to a feed 77 metalised on thef ST side 78 of the circuit board 70, which is shown in Figure 5B.
Referring to Figure 513, the first side 78 of the circuit board 70 is shown ha1v ag metalised thereon a second ground plane 79 and the feed 77. The second ground Pl, ne 79 is aligned with the launcher 72 on the second side 71 of the circuit board 70. 1 lie ground plane 79 is larger than the aperture in the ground plane 73 on the second si4e 71 of the circuit board 70, so as to shield the first side 78 (other than the area occupic d by 10 the ground plane) from the electromagnetic energy radiated by the launcher 72. T allows the remainder of the first side 78 to be occupied with electronic circuitry (I kDt shown), which is shielded from the launcher 72. Referring to Figure 6, the circuit board 70 of Figure 5 is mounted onto a base 80 by 15 supporting legs 81 and 82. The launcher 72 is on the uppermost surface of the citc ait board 70 as shown. A plastics lid 83, having downwardly-extending walls 84 and 815 is located on the base 80, surrounding the circuit board 70. A patch antenna 86 is attapI ed to the lowermost surface of the lid 83, the antenna being spaced from, and parallO,l to, the circuit board 70. The antenna 86 is spaced from the launcher 72 by a distance:o 5 20 mm. The antenna 86 is formed from aluminium foil cut into a rectangular shape.; I lie length of at least one of the sides of the antenna 86 is selected to correspond to integer multiple of half of the wavelength of the signals of interest. In this embodiq-ic the antenna 86 has a length of 6 cm, ie half of the wavelength of a 2.45 GHz signal in air. 25 In use, signals are radiated from the launcher 72 onto the antenna 86, which is thep by excited into radiating signals of the same frequency. Aside from the space sav'h Lgs which may be achieved using this invention, the antenna arrangement of Figure as an increased bandwidth and improved symmetry compared to the equivalent direol ly30 fed antenna arrangement. The increased bandwidth is especially advantageous whom a spread spectrum signal is used with the antenna arrangement. The Figure 6 antei ha 9 arrangement of Figure 6 also has better directivity, and is, therefore, of particular advantage when used in automotive alarm sensor applications.
Claims (8)
1. An antenna arrangement comprising an antenna having a length correspon4i. g substantially to an integer multiple of the half wavelength of a frequency of signalS' If interest, the antenna being grounded at a distance from an end of its 1(> i12th corresponding substantially to one quarter of the wavelength of the frequencyl:f interest. Preferably the antenna is a patch antenna.
2. An antenna arrangement comprising an antenna, a feed connected to the ant(,.1V,.,1, and a stub having a length corresponding substantially to an odd integer multiple o C 0 ic quarter of the wavelength of a desired signal frequency, the stub being connected to t feed at one end and being grounded at the other end.
3. An alarm sensor compnsing an oscillator arranged to provide output signals tel antenna, and a mixer arranged to mix the oscillator output signals with signals rec(,.ilv 1 by the or another antenna, the oscillator and the mixer each having a respeclip, semiconductor device.
4. An alarm sensor comprising an antenna, an oscillator, a mixer, a sensor circuit, 11 a temperature compensation circuit arranged to compensate at least in part temperature-dependent changes in sensitivity.
5. An alarm sensor according to claim 4, in which the temperature compensal.+ circuit is associated with the sensor circuit.
6. An alarm sensor according to claim 4, in which the temperature compensali( n circuit is associated with the mixer.
7. An alarm sensor according to claim 4, in which the temperature compensal,i(ii circuit is associated with the oscillator. 30
8. An alarm sensor according to claim 7, in which the temperature compensation circuit is arranged to vary the bias current of a transistor forming part of the oscillator with varying temperature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0001458A GB2358533A (en) | 2000-01-21 | 2000-01-21 | Antenna; feed; alarm sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0001458A GB2358533A (en) | 2000-01-21 | 2000-01-21 | Antenna; feed; alarm sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0001458D0 GB0001458D0 (en) | 2000-03-15 |
| GB2358533A true GB2358533A (en) | 2001-07-25 |
Family
ID=9884143
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0001458A Withdrawn GB2358533A (en) | 2000-01-21 | 2000-01-21 | Antenna; feed; alarm sensor |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2358533A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20220123473A1 (en) * | 2020-10-19 | 2022-04-21 | Qualcomm Incorporated | Shorted-stub antenna |
Citations (33)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1316087A (en) * | 1919-09-16 | Differential car wheel and axle | ||
| GB1312285A (en) * | 1970-09-11 | 1973-04-04 | Shorrock Dev | High-frequency intruder detector |
| GB1465925A (en) * | 1973-04-02 | 1977-03-02 | Lignes Telegraph Telephon | Moving target indicators |
| US4053895A (en) * | 1976-11-24 | 1977-10-11 | The United States Of America As Represented By The Secretary Of The Air Force | Electronically scanned microstrip antenna array |
| US4074214A (en) * | 1976-09-20 | 1978-02-14 | Motorola, Inc. | Microwave filter |
| US4103293A (en) * | 1975-11-21 | 1978-07-25 | Tri-Century Industries, Inc. | Intrusion alarm apparatus |
| US4195289A (en) * | 1975-12-03 | 1980-03-25 | I.E.I. Proprietary Limited | Microwave intrusion or movement detectors |
| US4241312A (en) * | 1979-07-27 | 1980-12-23 | Barnes James R | Self-calibrating threshold detector |
| US4417157A (en) * | 1979-09-11 | 1983-11-22 | E-Systems, Inc. | Radio frequency switch for coupling an RF source to a load |
| US4484163A (en) * | 1981-05-27 | 1984-11-20 | U.S. Philips Corporation | Arrangement for biasing high-frequency active components |
| US4489292A (en) * | 1982-01-22 | 1984-12-18 | Nippon Electric Co., Ltd. | Stub type bandpass filter |
| US4491809A (en) * | 1981-08-12 | 1985-01-01 | Hitachi, Ltd. | Matching circuit for a pre-amplifier of SHF band television signal receiver |
| EP0147925A1 (en) * | 1983-10-19 | 1985-07-10 | C & K Systems, Inc. | Combination infrared microwave intrusion detector |
| US4536725A (en) * | 1981-11-27 | 1985-08-20 | Licentia Patent-Verwaltungs-G.M.B.H. | Stripline filter |
| US4542358A (en) * | 1982-01-05 | 1985-09-17 | Societe Anonyme Dite: Les Cables De Lyon | Device protecting a coaxial cable against high-powered, low-frequency spurious pulses |
| US4696191A (en) * | 1986-06-24 | 1987-09-29 | The United States Of America As Represented By The United States Department Of Energy | Apparatus and method for void/particulate detection |
| US4700179A (en) * | 1982-04-12 | 1987-10-13 | Ici Americas Inc. | Crossed beam high frequency anti-theft system |
| EP0264056A2 (en) * | 1986-10-07 | 1988-04-20 | Sumitomo Electric Industries Limited | Vehicle antenna with shiftable gain patterns |
| US4757286A (en) * | 1986-07-04 | 1988-07-12 | Uniden Corporation | Microwave filter device |
| US4791420A (en) * | 1987-07-23 | 1988-12-13 | The Weston Corporation | Radar detector/security device for automobiles |
| EP0373452A2 (en) * | 1988-12-02 | 1990-06-20 | Fujitsu Limited | A second-harmonic-wave choking filter |
| US5028920A (en) * | 1984-02-10 | 1991-07-02 | Steven F. Sommers | Driver alerting device |
| GB2252676A (en) * | 1990-12-21 | 1992-08-12 | Marconi Gec Ltd | Patch antenna |
| EP0537798A1 (en) * | 1988-11-11 | 1993-04-21 | Matsushita Electric Industrial Co., Ltd. | Microwave filter |
| US5280256A (en) * | 1991-08-23 | 1994-01-18 | The United States Of America As Represented By The Secretary Of The Army | Limiting filter |
| GB2277640A (en) * | 1993-04-07 | 1994-11-02 | Woldroy Limited | Antenna |
| US5581236A (en) * | 1993-01-28 | 1996-12-03 | C & K Systems, Inc. | Methods and apparatus for intrusion detection having improved immunity to false alarms |
| WO1997007596A1 (en) * | 1995-08-21 | 1997-02-27 | Philips Electronics N.V. | A low voltage temperature and vcc compensated radio frequency mixer |
| GB2312098A (en) * | 1996-04-11 | 1997-10-15 | Siemens Ag | Antenna comprising two sides of circuit board |
| EP0803927A2 (en) * | 1996-04-26 | 1997-10-29 | SHARP Corporation | Attenuating filter for a DBS tuner for satellite broadcasting receivers |
| EP0831547A2 (en) * | 1996-09-20 | 1998-03-25 | Murata Manufacturing Co., Ltd. | Microstrip antenna |
| GB2327301A (en) * | 1997-07-11 | 1999-01-20 | Visonic Ltd | Microwave intruder detector using printed antenna |
| WO1999039432A1 (en) * | 1998-02-01 | 1999-08-05 | Marconi Aerospace Electronic Systems, Inc. | Structure and method for super fet mixer having logic-gate generated fet square-wave switching signal |
-
2000
- 2000-01-21 GB GB0001458A patent/GB2358533A/en not_active Withdrawn
Patent Citations (33)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1316087A (en) * | 1919-09-16 | Differential car wheel and axle | ||
| GB1312285A (en) * | 1970-09-11 | 1973-04-04 | Shorrock Dev | High-frequency intruder detector |
| GB1465925A (en) * | 1973-04-02 | 1977-03-02 | Lignes Telegraph Telephon | Moving target indicators |
| US4103293A (en) * | 1975-11-21 | 1978-07-25 | Tri-Century Industries, Inc. | Intrusion alarm apparatus |
| US4195289A (en) * | 1975-12-03 | 1980-03-25 | I.E.I. Proprietary Limited | Microwave intrusion or movement detectors |
| US4074214A (en) * | 1976-09-20 | 1978-02-14 | Motorola, Inc. | Microwave filter |
| US4053895A (en) * | 1976-11-24 | 1977-10-11 | The United States Of America As Represented By The Secretary Of The Air Force | Electronically scanned microstrip antenna array |
| US4241312A (en) * | 1979-07-27 | 1980-12-23 | Barnes James R | Self-calibrating threshold detector |
| US4417157A (en) * | 1979-09-11 | 1983-11-22 | E-Systems, Inc. | Radio frequency switch for coupling an RF source to a load |
| US4484163A (en) * | 1981-05-27 | 1984-11-20 | U.S. Philips Corporation | Arrangement for biasing high-frequency active components |
| US4491809A (en) * | 1981-08-12 | 1985-01-01 | Hitachi, Ltd. | Matching circuit for a pre-amplifier of SHF band television signal receiver |
| US4536725A (en) * | 1981-11-27 | 1985-08-20 | Licentia Patent-Verwaltungs-G.M.B.H. | Stripline filter |
| US4542358A (en) * | 1982-01-05 | 1985-09-17 | Societe Anonyme Dite: Les Cables De Lyon | Device protecting a coaxial cable against high-powered, low-frequency spurious pulses |
| US4489292A (en) * | 1982-01-22 | 1984-12-18 | Nippon Electric Co., Ltd. | Stub type bandpass filter |
| US4700179A (en) * | 1982-04-12 | 1987-10-13 | Ici Americas Inc. | Crossed beam high frequency anti-theft system |
| EP0147925A1 (en) * | 1983-10-19 | 1985-07-10 | C & K Systems, Inc. | Combination infrared microwave intrusion detector |
| US5028920A (en) * | 1984-02-10 | 1991-07-02 | Steven F. Sommers | Driver alerting device |
| US4696191A (en) * | 1986-06-24 | 1987-09-29 | The United States Of America As Represented By The United States Department Of Energy | Apparatus and method for void/particulate detection |
| US4757286A (en) * | 1986-07-04 | 1988-07-12 | Uniden Corporation | Microwave filter device |
| EP0264056A2 (en) * | 1986-10-07 | 1988-04-20 | Sumitomo Electric Industries Limited | Vehicle antenna with shiftable gain patterns |
| US4791420A (en) * | 1987-07-23 | 1988-12-13 | The Weston Corporation | Radar detector/security device for automobiles |
| EP0537798A1 (en) * | 1988-11-11 | 1993-04-21 | Matsushita Electric Industrial Co., Ltd. | Microwave filter |
| EP0373452A2 (en) * | 1988-12-02 | 1990-06-20 | Fujitsu Limited | A second-harmonic-wave choking filter |
| GB2252676A (en) * | 1990-12-21 | 1992-08-12 | Marconi Gec Ltd | Patch antenna |
| US5280256A (en) * | 1991-08-23 | 1994-01-18 | The United States Of America As Represented By The Secretary Of The Army | Limiting filter |
| US5581236A (en) * | 1993-01-28 | 1996-12-03 | C & K Systems, Inc. | Methods and apparatus for intrusion detection having improved immunity to false alarms |
| GB2277640A (en) * | 1993-04-07 | 1994-11-02 | Woldroy Limited | Antenna |
| WO1997007596A1 (en) * | 1995-08-21 | 1997-02-27 | Philips Electronics N.V. | A low voltage temperature and vcc compensated radio frequency mixer |
| GB2312098A (en) * | 1996-04-11 | 1997-10-15 | Siemens Ag | Antenna comprising two sides of circuit board |
| EP0803927A2 (en) * | 1996-04-26 | 1997-10-29 | SHARP Corporation | Attenuating filter for a DBS tuner for satellite broadcasting receivers |
| EP0831547A2 (en) * | 1996-09-20 | 1998-03-25 | Murata Manufacturing Co., Ltd. | Microstrip antenna |
| GB2327301A (en) * | 1997-07-11 | 1999-01-20 | Visonic Ltd | Microwave intruder detector using printed antenna |
| WO1999039432A1 (en) * | 1998-02-01 | 1999-08-05 | Marconi Aerospace Electronic Systems, Inc. | Structure and method for super fet mixer having logic-gate generated fet square-wave switching signal |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20220123473A1 (en) * | 2020-10-19 | 2022-04-21 | Qualcomm Incorporated | Shorted-stub antenna |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0001458D0 (en) | 2000-03-15 |
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