KR20020085105A - Short-ended coaxial slot-coupled strip array antenna - Google Patents

Abstract

PURPOSE: A short-ended coaxial slot-coupled strip array antenna is provided to improve efficiency of an antenna without using a half wavelength impedance converter. CONSTITUTION: The radiative efficiency of an antenna is increased by shortcircuiting an end portion of a coaxial waveguide. A plurality of slots is periodically formed on an external conductor of the coaxial waveguide. A dielectric is coated on the slots. The radiative efficiency is improved by forming periodical conductor strips and coupling the strips with an electromagnetic field. An additional feeding conversion device is unnecessary by forming an antenna feeder as a coaxial line. An antenna fabricating process is simplified by reducing a connecting process and an aligning process of an internal conductor and an external conductor. A loss due to surface wave power is disregarded since the since incident wave power is almost radiated to spacer wave power.

Description

Short-ended coaxial slot-coupled strip array antenna

In the present invention, a high antenna efficiency and antenna gain are obtained without the half-wave impedance converter required in the conventional electromagnetic coupled coaxial dipole array, and a structure that is easy to manufacture has been proposed. This structure eliminates the transmission wave through the short end of the coaxial waveguide and optimizes the length of the short end so that the radiation efficiency is maximized through the electromagnetic coupling with the strip through the slot.

The coaxial collinear antenna, which replaces the two-dimensional dipole array due to its simple feeding structure and structural simplicity, has been considered as a base station antenna, and has recently proved its usefulness as a PCS base station antenna through equivalent line analysis for coaxial collinear antennas and coaxial slot antennas. .

In addition, an electromagnetic coupled coaxial dipole array antenna composed of a half-wave conductor circular pipe, which is electromagnetically fed by an annular slot of an outer conductor of a feed coaxial line, is presented, suggesting the possibility as a base station antenna.

As a disadvantage of the conventional structure, the coaxial collinear antenna needs to be bonded with an inner conductor and an outer conductor, so that the bonding precision and element-to-element alignment are required, and the electromagnetically coupled coaxial dipole array antenna has a change in the dipole length and radius for impedance matching at the feeder. There are disadvantages to be given.

In the present invention, the coaxial collinear antenna needs to be bonded to the inner conductor and the outer conductor, so there is precision in bonding and difficulty in element alignment, and the electromagnetic coupled coaxial dipole array antenna has a 1 / 4λ converter design for impedance matching at the feeder. Required and must vary in dipole length and radius.

1 is an illustration of an electromagnetically coupled strip array antenna through a short-ended coaxial slot of the present invention.

Conventional coaxial collinear antennas have been considered as array elements replacing the two-dimensional dipole array because of their simple feeding structure. Due to its low cost and structural simplicity, it was considered as a base station antenna for personal mobile communication.

It consists of several half-wave coaxial lines, with the inner conductor of one line electrically connected to the outer conductor of the neighboring line, which excites voltage across all slots to induce an in-phase current distribution on the outer surface of the coaxial line. This in-phase and the same size allow for broad side gains.

Another type of antenna structure is an electromagnetically coupled coaxial dipole array antenna consisting of a half-wave conductor circular pipe that is electromagnetically fed by an annular slot on an outer conductor of a feed coaxial line. Interpreted. Here, the antenna characteristics were obtained by impedance matching by opening the coaxial waveguide terminal and setting the open length to be matched, and attaching a half-wave impedance converter to the feeder.

An electromagnetically coupled strip array antenna structure through a short-ended coaxial slot designed to increase antenna radiation efficiency is invented as shown in Figure 1.

In order to increase the radiation efficiency of the antenna, the end of the coaxial waveguide is electrically shorted.

Periodic slots are placed on the outer conductor of the coaxial waveguide, and dielectrics are coated on the outside of the slots, and periodical conductor strips are placed to increase the radiation efficiency to free space through electromagnetic coupling with the strips.

The antenna feed part is made of coaxial line, so it does not need a separate feed conversion device, and it is possible to use commonly used coaxial feed.

The antenna fabrication process is much simpler than coaxial collinear antennas that require connection and alignment of existing internal and external conductors.

Since the majority of incident power (Pinc) is radiated into the space power by the strong electromagnetic coupling between the slot and the strip, the surface wave power (Psurf) lost through the dielectric coating area in the form of surface wave is almost negligible and actually the terminator It can be used without design.

Various design parameters such as the short end length of the coaxial waveguide, the width of the coaxial waveguide slot, the width of the conductor strip, the relative permittivity of the coated dielectric, the thickness of the dielectric coating, and the like make it possible to obtain desired antenna patterns and characteristics.

The principle of operation of an electromagnetically coupled strip array antenna via a short-ended coaxial slot is as follows.

The TEM (Transverse Electromagnetic) wave, which is the basic mode of the coaxial waveguide, is incident by the antenna power supply generator.

Incident waves pass through each slot and are radiated into the space wave through strong electromagnetic coupling with the conductor strip, and some exit in the form of surface waves trapped in the coating area.

The remaining transmitted wave, which has been electromagnetically coupled, is reflected by the electrical termination of the antenna's termination and is again radiated through the electromagnetic coupling with the conductor strip through the slot.

Match the exiting with the surface wave corresponding to the minimum by Terminator and eliminate the reflection. In fact, less than 1% of the incident power, there is no problem if you do not have a terminator.

The present invention is easier to fabricate than a coaxial collinear antenna that requires the connection and alignment of existing coaxial waveguide inner and outer conductors.

The feeding structure has the same coaxial feeding structure as the existing coaxial collinear, and thus can be used without changing the feeding structure.

The dielectric coating on the outside of the outer conductor replaces Radome's ability to protect the electrical properties inside the slot from the outside environment.

There are more design parameters than conventional ones, so there are various factors to meet the required performance.

The antenna of the present invention can be replaced with the conventional one out of the characteristics of the antenna for commercial base stations, there is an advantage that can be sufficiently used as an antenna of the millimeter wave band in the future.

When the antenna of the present invention is used, the feeding structure is simple and easy to manufacture, and also has excellent antenna radiation characteristics, so that it can be used to replace the existing base station antenna for mobile communication.

Claims (1)

Electromagnetically coupled strip array antenna via short-ended coaxial slots.