RU2074406C1 - Module of doppler radar - Google Patents

Abstract

FIELD: radiolocation. SUBSTANCE: proposed invention can be used in devices for detection of movements of man and various objects and for burglar alarm in different rooms. Module additionally includes conductive screen layer and dielectric layer. Transistor with load in the form of stripline antenna is used for generation of signal. Biasing of radiated and received signals is carried out on emitter junction of same transistor. As result module does not need waveguide, circulator, mixer diode, waveguide-stripline junctions. Lack of waveguide-stripline junctions enables range of action of module to be increased as there is no less of power of SHF signal. EFFECT: simplified design and increased range of action of module. 6 cl, 1 dwg

Description

 The invention relates to radio engineering, and more specifically to devices for detecting the movement of a person and various objects, and can be used for burglar alarms in various rooms.

 A known Doppler radar module comprising a dielectric layer, an antenna, an active element unit connected to a radiating end of an antenna located on a dielectric layer (Microwave Plus Passine Jnfrared Detector MICRO-X from Electronics Line (EL) Ltd).

 The disadvantages of this module include greater complexity, i.e. the active element is carried out separately from the strip antenna, which necessitates special matching circuits for the generator and mixer.

 The closest technical solution to the proposed and adopted as a prototype is a Doppler radar module containing an antenna, coupler element, generator element (Japanese application 56-100369, publ. 1981, class G 01 S 13/50, 7/02).

 A disadvantage of the known technical solution is its complexity, because To transmit a signal from a generator to a radiating antenna and from an antenna to a mixing diode, a complex waveguide, resonator, and circulator are required.

 Multiplication of the emitted and received signal is performed on a special element of the mixing diode, and to transfer part of the power from the generator to the mixing diode, a special element is also required - a directional coupler.

 To match the generator and the mixing diode with a rectangular waveguide, a waveguide-strip transition is necessary.

 Another disadvantage of the known module is the limited range, because matching transitions are not located at the maximum concentration of the microwave electric field.

 The purpose of the invention is to simplify the module and increase the range of its action.

 The goal is achieved in that the Doppler radar module containing the antenna, the coupler element, the generator element further comprises a conductive shielding layer, a dielectric layer located on the conductive shielding layer, the antenna being rectangular in shape and located on the dielectric layer, the first and second microwave filters oscillations, the generator element is made on a transistor, the collector of which is connected to the radiating end of the antenna, an emitter with the first output of the first filter of microwave oscillations, the second in the water of which is the output of the module, the first output of the second microwave filter is connected to the base of the transistor, and the second output is the first input of the bias of the module, the coupler element is made in the form of a conductive strip located on the dielectric layer along the radiating end of the antenna, and the first end of the conductive strip connected to the base of the transistor, the second bias input of the module is connected to the non-radiating end of the antenna.

,
l_и длина излучающих торцов антенны;
l_н.и длина неизлучающих торцов антенны;
ε_д диэлектрическая проницаемость диэлектрического слоя.To further increase the range of the radar, the lengths of the radiating and non-radiating ends of the antenna are correlated as follows:

,
l _{and the} length of the radiating ends of the antenna;
l _{N. and the} length of the non-radiating ends of the antenna;
ε _{d is the} dielectric constant of the dielectric layer.

средняя диэлектрическая проницаемость слоев, составляющих диэлектрический слой.To increase the efficiency of the module, the dielectric layer can be multilayer. In this case, the lengths of the radiating and non-radiating ends of the antenna are correlated as follows:

the average dielectric constant of the layers constituting the dielectric layer.

 To increase the efficiency of the module, it may contain a rectangular conductive region located on the dielectric layer adjacent to the second end of the conductive strip of the coupler element.

 The proposed Doppler radar module has the following new features compared to the prototype: the presence of a conductive shielding layer, a dielectric layer, the execution of the generator element on the transistor, the implementation of the coupler element in the form of a conductive strip of the first and second microwave oscillation filters, as well as the relative position of the above elements.

 The implementation of the rectangular antenna and its location on the dielectric layer is a feature known from other technical solutions (Microwove Plus Passive Jnfrared Detector MICRO-X from Electronics Line (EL) Ltd.).

 The implementation of the generator element on the transistor can significantly simplify the module, because the transistor in combination with the antenna generates microwave oscillations, and at the same time the emitter-base transition of the transistor performs the function of multiplying the emitted signal and the received signal. Reception of the reflected signal is made by the same antenna. This feature allows you to exclude from the module separately executed in the prototype generator, mixing diode, strip waveguides.

 The implementation of the element of the coupler in the form of a conductive strip with a specified location relative to the antenna also allows you to simplify the module, because transmission from part of the received power of the microwave signal to the coupler element and, accordingly, to the transistor base is made directly from the radiating end of the antenna. This avoids the use of a coupler as a special element in the module, as well as associated strip waveguides.

 Microwave energy filters are designed for decoupling the microwave signal paths from the low-frequency output of the module, and from the bias circuits of the emitter junction of the transistor.

 The implementation of the antenna with the specified ratio of the lengths of the radiating and non-radiating ends allows you to increase the efficiency of the module, because while the generator on the transistor and the antenna operates at a given frequency in resonance. The implementation of the dielectric layer multilayer allows you to optimally choose a combination of dielectric materials to reduce the tangent of the loss angle in it.

 The presence of a rectangular conducting region allows you to optimize the power transmitted from the antenna to the base of the transistor, depending on the choice of operating frequency.

 The drawing shows a view of the Doppler radar module in plan.

 The module contains a conductive shielding layer 1, a dielectric layer 2, an antenna 3, a transistor 4, the collector of which is connected to the radiating end of the antenna 3, a first microwave oscillation filter 5, a second microwave energy filter 6, a conductive strip 7 of the coupler element, a conductive region 8 of a rectangular shape. The second output of the filter 5 is the output 9 of the module, and the second output of the filter 6 is the first input 10 of the offset module. The second input 11 of the bias module. Filters 5, 6, depending on the operating frequency, can be conductors (for higher frequencies) or chokes (for lower frequencies). The implementation of filters is not an essential feature of this device and is known from the literature (Elements of electronic equipment, vol. 48, M. Radio and communications, 1985, p. 20, Fig. 1.15).

 The Doppler radar module is a heterodyne type Doppler system and operates as follows.

. Часть принятой антенной 3 мощности передается в элемент 7 ответвителя, а из него на эмиттерный переход транзистора 4. На эмиттерном переходе, который является смесителем, принимаемая частота преобразуется в напряжение на выходе 9 модуля на частоте

V скорость перемещения объекта;
λ_o длина волны, излучаемой антенной 3;
f_o частота, излучаемая антенной 3;
f_д доплеровская частота.Antenna 3 emits microwave energy into the space with a frequency f _o , which is generated in a resonant system consisting of a transistor 4 and antenna 3. The oscillation energy reflected from a moving object is received by the same antenna 3 at a frequency

. Part of the power received by antenna 3 is transmitted to the coupler element 7, and from there to the emitter junction of transistor 4. At the emitter junction, which is a mixer, the received frequency is converted to voltage at the output of module 9 at a frequency

V is the speed of the object;
λ _o the wavelength emitted by the antenna 3;
f _{o the} frequency radiated by the antenna 3;
f _d Doppler frequency.

Tuning the generator on transistor 4 in frequency is carried out by choosing the length of the non-radiating ends of the rectangular antenna 3, which is the load of the transistor 4,
l _and = 0.5λ _o , where
l _{and the} length of the radiating ends of the antenna 3.

 Since transistor 4 must operate in the "common base" mode, a constant voltage must be applied to its base, which for a microwave signal is equivalent to the ground potential. Filter 6 represents a significant resistance for the microwave signal and ensures maximum passage of the microwave signal to the base of the transistor. At the same time, filter 6 does not prevent a constant bias from being applied to the base of transistor 4. Similarly, filter 5 passes a low Doppler frequency to the output, delaying the microwave signal.

l_н.и длина неизлучающих торцов антенны 3;
ε_д относительная диэлектрическая проницаемость диэлектрического слоя 2.The highest radiation power of the antenna 3 is achieved when the generator operates in resonance. The resonance condition is

l _{N. and the} length of the non-radiating ends of the antenna 3;
ε _{d the} relative dielectric constant of the dielectric layer 2.

Для уменьшения тангенса угла потерь в диэлектрике, слой 2 может представлять собой композицию из нескольких диэлектрических материалов, в том числе и воздуха. В этом случае в формуле для соотношения длин излучающих и неизлучающих торцов берется средняя диэлектрическая проницаемость.To work in resonance, the ratio of the length of the radiating and non-radiating ends of the antenna must be

To reduce the loss tangent of the dielectric, layer 2 may be a composition of several dielectric materials, including air. In this case, the average dielectric constant is taken in the formula for the ratio of the lengths of the radiating and non-radiating ends.

The optimum is the dielectric constant ε _d = 2.5-10 and the loss tangent tg≈10 ^-4 10 ^-3 . The thickness of the dielectric layer 2 may be (0.1 ÷ 0.01) λ _o ..

 To increase the efficiency of the module, the second input 11 of the bias of the module can be connected to the middle of the radiating end of the antenna 3, because at this point is the virtual zero of the microwave energy potential. The location of the contact at another point of the non-radiating end shorts part of the microwave currents to the ground, which reduces the efficiency.

Claims (6)

 1. A Doppler radar module containing a dielectric substrate, on one side of which there is a conductive shielding layer, and on the other a rectangular strip antenna, a first decoupling filter and a conductive strip located parallel to one of the antenna ends, as well as the first and second bias circuit terminals, characterized the fact that the input element is made on the transistor, and the second decoupling filter, the first output of which is connected to the emitter of the transistor, and the second output is the output m having pulled, the collector of the transistor is connected to the radiating end of the antenna, to the non-radiating end of which the first output of the bias circuit is connected, the conductive strip is located along the radiating end of the antenna and is connected at one end to the base of the transistor and to the first terminal of the first decoupling filter, the second terminal of which is connected to the second terminal of the circuit displacement. 2. The module according to claim 1, characterized in that the lengths of the radiating and non-radiating ends of the antenna are selected from the ratio

where l _{and the} length of the radiating end of the antenna;
l _{n. and the} length of the non-radiating end of the antenna;
ε _{d is the} dielectric constant of the material of the dielectric substrate.  3. The module according to claim 1, characterized in that the dielectric substrate is multilayer. 4. The module according to claim 3, characterized in that the lengths of the radiating and non-radiating ends of the antenna are selected from the ratio

where ε _{d.cp is the} average dielectric constant of the materials constituting the dielectric substrate.  5. The module according to claim 1, or 2, or 3, or 4, characterized in that the end of the conductive substrate is provided with a conductive rectangular plate.  6. The module according to claim 1, or 2, or 3, or 4, or 5, characterized in that the first output of the bias circuit is connected to the middle of the non-radiating end of the antenna.