RU2793081C1 - Q-range microband antenna array - Google Patents

Abstract

FIELD: antenna equipment.

SUBSTANCE: invention relates to antenna equipment, in particular to UHF range printed antennas, and serves as an irradiator of a parabolic antenna of mobile terminals. Q-range printed antenna array is proposed, which includes functionally and structurally connected printed active irradiators, as well as two-stage power divider forming an asymmetric microband line and passive irradiators, while eight active irradiators in the form of rectangular metal plates have four cutouts, which, together with parallel outer sides of active irradiators, create electromagnetic radiation, and a passive irradiator in the form of a rectangular metal plate is placed next to each active irradiator to form a side connection. The power divider consists of T-shaped primary divider performing primary division of signal power and two symmetrically located and connected in parallel T-shaped secondary dividers providing signal transmission from the first divider arms to each active irradiator.

EFFECT: formation of directional characteristics not worse than those of horn antennas to irradiate a parabolic mirror, reduction in overall dimensions, and expansion of a working frequency band.

3 cl, 6 dwg

Description

The invention relates to microwave technology, in particular to printed antennas, and is intended for use as a parabolic antenna feed for mobile satellite communication terminals and in other broadband transceiver devices.

A known design of a printed antenna array for transmitting information in the millimeter frequency range, described in the patent [US 7675466 B2 dated March 9, 2010], which uses coupled lines to distribute energy between the radiating elements and the supply line.

The disadvantages of the known design are a narrow band of operating frequencies and high accuracy requirements for ensuring small gaps between the conductors to obtain a given value of the voltage coupling coefficient, which complicates the manufacturing technology of the antenna.

A known design of a printed antenna array [US 9391375 B1 dated 07/12/2016] with a slot method of excitation of printed emitters.

The disadvantage of the known design is the narrow band of operating frequencies and the additional parasitic effect of the supply lines - the added capacitance created in the dielectric between the strip radiator, the layers with a gap and the supply lines.

The closest technical solution, taken as a prototype, is an antenna array [SU 1756992 A1 dated 11/23/1989], designed to transmit linear polarization signals and containing a dielectric substrate, on one side of which there is a metal screen, on the other - a microstrip power divider and rectangular strip radiators.

The disadvantage of the prototype is the narrow band of the operating frequency, which is limited not only by the bandwidth of the used radiating elements, but also by the distribution line.

The objective of the invention is the formation of directional characteristics (width of the radiation pattern, gain, direction of the radiation maximum) no worse than those of horn antennas that act as feeds for a parabolic mirror, reduction in overall dimensions and expansion of the operating frequency band.

The technical result is achieved due to the fact that the microstrip antenna, which is a printed antenna array, into which active radiators are functionally and structurally connected and made with the original geometry of the printed pattern, as well as a two-stage power divider forming an asymmetric microstrip line and passive ( parasitic) radiators, while eight active radiators in the form of rectangular metal plates have four cutouts, which, together with the outer sides of the active radiators parallel to them, create electromagnetic radiation, and each active radiator has a passive radiator in the form of a rectangular metal plate in such a way that between they were lateral (capacitive) connection; The power divider consists of a T-shaped primary divider that performs the initial division of the signal power, quarter-wave impedance transformers and two symmetrically located relative to each other and connected in parallel T-shaped secondary dividers that provide signal transmission from the arms of the first divider to each active radiator, and which with a supply line are the connecting link between the active emitters and the input port, and the excitation of active emitters is carried out due to their direct connection with the power divider. In this case, the microwave signal is fed through the input connector of the antenna to the supply line and enters the input of the primary divider, from which it is fed through quarter-wave transformers to the arms of two secondary dividers and enters the active radiators, where the electric field is excited in the gaps of the active radiators, which ensures co-directional the flow of an equivalent current along each of the sides of the antenna, parallel to the cutouts, and the excitation of an electromagnetic wave by six sections of the current flow in each active radiator. The currents flowing along the edges of active radiators, using capacitive coupling through the gap, create inductive conduction currents on parallel sides of passive radiators, acting as a passive resonator, changing the shape of the radiation pattern, directing radio waves emitted by active radiators into one beam, increasing the directivity of the antenna array . Passive radiators are tuned to a lower frequency relative to the operating range of the antenna and, thereby, expand the operating frequency band; in addition, the effect of expanding the operating frequency band compared to the traditional, rectangular active radiator is achieved by adding cutouts of different lengths in it.

The microstrip Q-band antenna array is shown in the drawings:

- fig. 1 - axonometric schematic representation of the antenna;

- fig. 2 is a top view of the radiating side of the antenna;

- fig. 3 is a plot of the voltage standing wave ratio versus frequency;

- fig. 4 - radiation pattern of the microstrip antenna array in the H-plane in the Cartesian coordinate system;

- fig. 5 - radiation pattern of the microstrip antenna array in the E-plane in the Cartesian coordinate system;

- fig. 6 is a plot of the maximum gain of the microstrip antenna array versus frequency;

The design of the Q-band microstrip antenna array is shown in Fig. 1 and 2, where the following designations are used: 1 - conductive pattern; 2 - substrate; 3 - screen; 4 - antenna power connector; 5 - supply line; 6 - primary power divider; 7 - secondary power divider with quarter-wave transformers; 8 - active emitter; 9 - passive radiator.

All eight active radiators are made in the form of rectangular microstrip antennas with four cutouts (see Fig. 2), which, together with the outer sides of the radiators parallel to them, create electromagnetic radiation.

The width of the active radiator, obtained experimentally, depends on the wavelength in the line λ _B calculated at the center frequency of the operating range:

с - скорость света, м/с; fв и fн - верхняя и нижняя границы рабочего диапазона частот; ε - диэлектрическая проницаемость материала подложки.Where

c is the speed of light, m/s; fv and fn - upper and lower limits of the operating frequency range; ε is the permittivity of the substrate material.

The emitter length was calculated by the formula:

Additionally, each active radiator has a passive radiator in such a way that there is a lateral capacitive coupling between each active and the corresponding passive radiators.

Dividers with a feed line are the link between the active radiators and the input port and perform the distribution of the signal coming from the antenna power connector. At the same time, the dividers and the supply line, together with active emitters, are made in the form of an asymmetric microstrip line on a substrate common in production for microwave printed circuit boards, for example, brand RO4003C, thickness h=0.508 mm, dielectric constant ε=3.55 and dielectric loss tangent tgδ= 0.0027.

The claimed antenna works as follows. The microwave signal is fed to the input connector of the antenna 4, from it, through the supply line 5, it enters the input of the primary power divider 6, being distributed, passes through the quarter-wave transformers to the output arms of the two secondary dividers 7 and enters the active radiators 8. An electric field is excited in the cutouts active radiators, which ensures the co-directional flow of the equivalent current along each of the outer sides of the antenna, parallel to the gaps of the active elements, and the excitation of an electromagnetic wave by six sections of the current flow in each active radiator. The currents flowing along the edges of active radiators, due to capacitive coupling through the gap, create inductive conduction currents on the parallel sides of passive radiators 9, acting as passive resonators, changing the shape of the radiation pattern, directing radio waves emitted by active radiators into one beam, increasing the directivity of the antenna gratings. Passive radiators are tuned to the lower frequency of the antenna's operating range and, thereby, expand the operating frequency band.

In addition, the effect of expanding the operating frequency band compared to an antenna with traditional rectangular (without cutouts) active radiators is achieved by adding cutouts of different lengths in it.

As can be seen from the plot of the standing wave ratio (VSWR) for voltage versus frequency (see Fig. 3), obtained by electrodynamic simulation using the CST Suite Studio software product, the power loss in the microstrip line does not exceed 25% at VSWR ≤ 3 within frequencies marked on the graph, and at frequencies of 40 GHz and 44 GHz, the losses are below 10%. In FIG. Figure 4 shows the antenna radiation pattern in the H-plane in the Cartesian coordinate system, which shows that at a frequency of 40 GHz, the radiation maximum is directed parallel to the normal to the antenna plane and is approximately 11 dB (main lobe), with increasing frequency, several maxima are formed. In FIG. 5 shows the radiation pattern in the E-plane, which shows that the direction of the maximum radiation, which is 13.5 dB, also falls on the normal to the plane of the antenna. The dependence of the maximum antenna gain on frequency, shown in the graph of Fig. 6 shows that the antenna has maximum gain at 40 GHz (which is also illustrated by the plots of FIGS. 4 and 5).

The overall dimensions of the antenna, obtained experimentally, are: 34.6×30.0×0.578 mm.

The original shape of the longitudinal cutouts of active radiators provides radiation at the upper limit of the working frequency range of the antenna, the outer side edges of the radiators create electromagnetic radiation at the lower limit of the frequency range.

In the proposed design of the microstrip antenna, the excitation of active radiators is provided using an asymmetric microstrip transmission line laid between active radiators, the distance between the centers of which does not exceed 1.1 wavelengths of the radiated electromagnetic field to obtain the maximum gain towards the normal of the antenna plane, and also - for transmitting a signal in the frequency range from 39 GHz to 46 GHz with a power loss not exceeding 11% of the power supplied to the antenna connector in the specified frequency range (the level of the voltage standing wave ratio is less than two).

The technical result consists in achieving directional characteristics (width of the radiation pattern, gain, direction of the radiation maximum) comparable with the characteristics of horn antennas acting as feeds of a parabolic mirror, as well as in reducing the overall dimensions and expanding the operating frequency band compared to analogues.

Claims (3)

1. Q-band microstrip antenna array, which is a printed antenna array, the design of which includes functionally and structurally connected printed active radiators, as well as a two-stage power divider that forms an asymmetric microstrip line and passive radiators, with eight active radiators in the form rectangular metal plates have four cutouts, which, together with the outer sides of the active emitters parallel to them, create electromagnetic radiation, and each active emitter has a passive emitter in the form of a rectangular metal plate so that there is a lateral connection between them; The power divider consists of a T-shaped primary divider, which initially divides the signal power, and two T-shaped secondary dividers symmetrically located relative to each other and connected in parallel, ensuring signal transmission from the arms of the first divider to each active radiator, and which, with the supply line, are a link between the active emitters and the input port, and the excitation of active emitters is carried out due to their direct connection with the power divider. 2. Microstrip Q-band antenna array according to claim 1, characterized in that the asymmetric microstrip transmission line that excites the radiators is laid between active radiators, the distance between the centers of which does not exceed 1.1 wavelengths of the radiated electromagnetic field to obtain the maximum gain towards normal to the antenna plane, and is configured to transmit a signal in the frequency range from 39 to 46 GHz with power losses of not more than 11% of the power supplied to the antenna connector, in the entire frequency range in terms of the voltage standing wave ratio level below two. 3. Microstrip Q-band antenna array according to claim 1, characterized by cutouts of different lengths in the geometric shape of active radiators, which are secondary sources of electromagnetic radiation in relation to the outer side edges of the active radiators and determine the upper limit of the operating frequency range of the radiation of the antenna 46 GHz.

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