Microstrip antenna

 

The invention relates to the field of antenna technology and is intended for use in radio systems for various purposes. Microstrip antenna contains two planar dielectric plates lying one on the other, the lower of which is made asymmetric strip line conductor and a grounding plate supply through capacitive coupling planar radiating elements, made on the outer side of the upper dielectric plate in the form of rectangular metal plates alternately arranged in different directions relative to the conductor microstrip line. The dimensions of the radiating elements and the distances between them vary along the conductor asymmetric strip line according to the principle of logarithmic periodicity. To stabilize the width and direction of maximum beam within the working range of frequencies simultaneously and in phase included the second microstrip antenna, identical to the first, located it in the same plane on a common longitudinal axis and which is its reflection on the part of the radiating element with a minimum size. The distance between the lowest emitting elements hr/955.gif">min- the minimum wavelength of the operating frequency range. Parallel and in-phase connection of microstrip antennas and can be carried out by any known method, for example, by dual power splitter. The technical result is to stabilize the width and direction of maximum radiation pattern in the frequency range. 1 Il.

The invention relates to the field of antenna technology and is intended for use in radio systems for various purposes, in particular in wide-band portable radio systems.

Known microstrip antennas [1,2], with small weight and dimensions, good frequency characteristics in mass production, low cost and adaptability.

A significant disadvantage is the narrow band of operating frequencies.

Closest to the technical nature of the claimed invention is selected as a prototype microstrip antenna [3], containing two planar dielectric plates lying one on the other, the lower of which is made asymmetric strip line feeding through capacitive coupling flat emitting eih plates, alternately located in different directions relative to the conductor asymmetric strip line. With the aim of expanding the band of operating frequencies the dimensions of the radiating elements and the distances between them vary along the asymmetric strip line according to the principle of logarithmic periodicity. The pattern of this microstrip antenna is directed along the normal to the plane of the dielectric plates.

The experimental sample of microstrip antennas is investigated in the prototype, had a frequency of the order of 30%. At the same time, from the point of view of matching supply with asymmetric strip line, such microstrip antenna can operate in the frequency band more than an octave.

Significant disadvantages of microstrip antennas [3], limiting its use as a broadband antenna of a portable radio unit is the instability of the width of its pattern and direction of maximum radiation in the frequency range. In particular, conducted by the author studies have shown that disabling maximum beam from the normal to the plane of the dielectric plate reaches twice the bandwidth h is mind pattern in the frequency range.

The task is achieved by the fact that the microstrip antenna that contains two planar dielectric plates lying one on the other, the lower of which is made asymmetric strip line feeding through capacitive coupling planar radiating elements, made on the outer side of the upper dielectric plate in the form of rectangular metal plates alternately arranged in different directions relative to the conductor asymmetric strip line, and the sizes of the emitting elements and the distances between them vary along the conductor asymmetric strip line according to the principle of logarithmic periodicity, according to the invention in parallel and in phase included the second microstrip antenna, identical to the first, found it in one plane on a common longitudinal axis and which is its reflection on the part of the radiating element with a minimum size, and the distance between the lowest emitting elements of the first and second micropa-Laskovich antennas selected in the range of (0.3 to 0.5)minwheremin- the minimum wavelength of the operating frequency range.

Comparative analysis with about parallel and in phase included the second antenna, identical to the first, located it in the same plane on a common longitudinal axis and which is its mirror image, and the distance between the lowest emitting elements of the first and second microstrip antennas are selected in a certain way.

Thus, the invention meets the criterion of “Novelty.”

Analysis of the known technical solutions known in the area and adjacent allow us to conclude that these symptoms are known, but the properties that thanks to them acquires the invention, leads to stabilization of the width and direction of maximum radiation pattern in the frequency range, providing a positive effect and gives grounds to conclude that the technical solutions according to the criterion of “significant differences”.

The invention involves an inventive step, because the specialist is not obvious from the prior art.

The invention is industrially applicable as it can be used in various fields of national economy.

In Fig.1 shows a schematic representation of a microstrip antenna, where:

1 - the first microstrip antenna;

2 - the second microstrip antenna;

3 is a top dielectric plate;

7 - grounding plate asymmetric strip line;

8 - channel power divider;

R - active load.

Microstrip antenna 1 or 2 contains two planar dielectric plates 3 and 4, lying one on the other, the lower of which is made asymmetric strip line. Explorer 6 asymmetric strip line located on the upper side of the dielectric plate 4, on which lies the second dielectric plate 3. The lower side of the dielectric plate 4 has a metallization role of the grounding plate 7 asymmetric strip line. On the upper side of the dielectric plate 3 is made in the form of rectangular metal plates radiating elements 5, are alternately located in different directions relative to the conductor 6 of the asymmetric strip line. The dimensions of the radiating elements and the distances between them vary along conductor 6 asymmetric strip line according to the principle of logarithmic periodicity. The first microstrip antenna 1 and the second microstrip antenna 2 are located in one plane on a common longitudinal axis. After this, the second microstrip antenna 2 is a mirror image of the first microstrip mi 5 with a minimum size selected in the range of (0.3 to 0.5)min. Structurally, both microstrip antennas 1 and 2 can be performed on a single dielectric plates 3 and 4. Each of microstrip antennas 1 and 2 has its own independent asymmetric strip line, loaded with side emitting elements 5 with a maximum size on the resistance R, and the side emitting elements 5 with minimum dimensions of both asymmetric strip lines are connected in parallel and in phase. Parallel and in-phase connection of microstrip antennas 1 and 2 can be carried out by any known method, for example, by dual power splitter 8.

Microstrip antenna operates as follows.

The signal generator is included in the entrance channel of the power splitter 8, excites in single-ended strip lines, microstrip antennas 1 and 2 THE wave. Asymmetric strip line, loaded emitting elements 5, equivalent to a line parallel conductances. If emitting elements 5 located near the top, for example, microstrip antenna 1 (near the point of feed), the resonance frequency is much higher than the frequency of the signal generator, the equivalent prone this section only to a slight deceleration of the propagating wave. As the wave propagation along a microstrip antenna 1 or 2 and bring it to the so-called “active region” where the resonant frequency emitting elements 5 is close to the frequency of the signal generator, shunt conductance increase and more and more influence propagation in asymmetric strip line wave. In the “active area” is equivalent conductivity is very high in relation to wave conductivity asymmetric strip line and is active in nature, so the energy from the asymmetric strip line enters emitting elements 5, included in the “active region”, and radiates them. The remainder emitting elements 5 located outside of the “active region”, in fact, does not affect the operation of microstrip antennas 1 and 2. When changing the frequency of the signal generator hotspot moves along the microstrip antenna 1 and 2, providing them with broadband. The relative phase of the currents in the adjacent light emitting elements 5, due to their location along the asymmetric strip line, is approximately equal to 180. Alternating their location relative to the conductor 6 of the asymmetric strip line on agenie fields at the point of reception. When the common mode ravnoapostolnomu the distribution of currents in studying the elements 5 microstrip antennas 1 and 2 form a unidirectional pattern, the directions of maximum radiation which is directed normal to the plane of the dielectric plates 3, 4. Amplitude-phase distribution of the currents in the radiating elements 5 forming an active region depends on their size, precision manufacturing and the degree of capacitive coupling with the conductor 6 asymmetric strip line. Since the sizes of the emitting elements 5 and the degree of their capacitive coupling with the conductor 6 (at a constant thickness of the dielectric plate 3) are different, the distribution of currents in them will be different from ravnoapostolnogo phase distribution. When this amplitude and phase errors excitation emitting elements 5 increase with increasing frequency, which leads to a distortion of the shape of the pattern and change in the direction of maximum radiation. In this case, as is known, the direction of maximum radiation deviates from the normal to the side emitting elements 5 with minimum dimensions. As introduced microstrip antenna 2 identical microstrip antenna 1 is located with it in one plosko the s direction of the radiation from the normal will be the same value as the microstrip antenna 1, but in the opposite direction. When in-phase addition of the resulting radiation will take constant direction, namely, along the normal to the plane of the dielectric plates 3, 4. However, the selected value of the distance d between the radiating elements 5 with a minimum size (0,3mind0,5min) eliminates the possibility of interference maxima in the resulting pattern and the change of the input impedance due to the mutual influence of microstrip antennas 1 and 2 to each other. Thus, the introduction microstrip antenna 2 as stated above leads to the fact that the deviation pattern of one microstrip antenna in the operating frequency range is in sync with the off pattern to another, but in opposite directions, so their resultant pattern occupies a stable position in space over the entire operating frequency range. As with increasing frequency pattern of each individual microstrip antenna is narrowed, and od is the directional diagrams from two separate microstrip antennas 1 and 2 at different frequencies will be carried out at different levels of their intersection, ensure the constancy of the width of the resulting pattern and, as a consequence, the gain in the operating frequency range.

Manufactured in accordance with the proposed technical solution, the layout of the microstrip antenna and the measurement results confirmed theoretical background. In particular, in octave band frequency deviation maximum beam was3the uneven pattern width, including measurement error amounted to no more than5%. In addition, the increase in gain compared with the prototype was (1,6-1,9) dB.

Sources of information

1. Patent U.S. CL 343/700 (H 01 Q 00/00) no 4163236 from 31.07.79.

2. Patent U.S. CL 343/700 (H 01 Q 1/38) No. 4160976 from 10.07.79.

3. ELECTRONICS LETTERS. 1980, 14 February, v.16, No. 4, p. 127-128.

Claims

Microstrip antenna that contains two planar dielectric plates lying one on the other, the lower of which is made asymmetric strip line feeding through capacitive coupling planar radiating elements, made on the outer side of the upper dielectric plate in the form of a rectangle is Raskovoy line, the sizes of the emitting elements and the distances between them vary along the conductor asymmetric strip line according to the principle of logarithmic periodicity, characterized in that in parallel and in phase included the second microstrip antenna, identical to the first, located it in the same plane on a common longitudinal axis and which is its reflection on the part of the radiating element with a minimum size, and the distance between the lowest emitting elements of the first and second microstrip antennas selected in the range of (0.3 to 0.5)minwheremin- the minimum wavelength of the operating frequency range.

 

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