JPH0746762B2 - Circularly polarized microstrip antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a circularly polarized microstrip antenna, and particularly to the movement of an aircraft, a vehicle, or the like that requires a circularly polarized wave pattern over a wide angle from the zenith region to the low elevation angle region. The present invention relates to a circularly polarized microstrip antenna having a two-layer structure suitable for application to body-mounted antennas.

[Conventional technology]

Conventionally, this type of double-layered circularly polarized antenna excites the microstrip antennas (MSA) placed above and below by the main mode, so its coverage area covers only the zenith and its neighboring area. Stayed. Moreover, the circularly polarized microstrip antenna using the higher-order mode has a single-layer structure that covers only the low elevation angle region.

[Problems to be solved by the invention]

The above-mentioned conventional circular polarization MSA is a main mode excitation two-layer structure circular polarization MSA that covers only the zenith and its vicinity region,
Since it is limited to high-order mode excitation single-layer structure circularly polarized MSA that covers only the low elevation angle region, it is difficult to cover a wide coverage area from the zenith region to the low elevation angle region with one antenna system. there were.

Therefore, it is an object of the present invention to provide a circularly polarized MSA capable of covering a wide range of coverage from the zenith region to the low elevation angle region.

[Means for solving problems]

Circular polarization MSA of the present invention, on the upper surface of the MSA for higher-order mode excitation,
It has a two-layer structure in which the MSA for main mode excitation is closely loaded coaxially.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

Referring to FIGS. 1 and 2, one embodiment of the present invention shows that the main mode (TM) is set on the upper surface of the MSA2 for high-order mode (TM ₂₁ mode, etc.) excitation.
_11- mode) It has a double structure in which the excitation MSA1 is closely loaded on the same axis. In addition, the present embodiment further compensates for the symmetry of the main mode and the higher modes with the low permittivity substrates 3 and 6 for the antenna part and the feed circuit configuration having the relative permittivity εr = 2.5 and values in the vicinity thereof, respectively. Center pin 4 arranged on the central axis of the MSA and ground conductor 5 of the dielectric substrate under test
And probes F ₁ and F ₂ for main mode excitation and probes G ₁ , G ₁ ′, G ₂ and G ₂ ′ for higher mode excitation.

Electromagnetic waves having a phase difference of + 90 ° or −90 ° generate circularly polarized waves, and are thus fed to two spatially orthogonal main mode excitation probes F ₁ and F ₂ . Probe F ₁ and
F ₂ is the antenna part substrate 3 and the ground conductor 5 in a non-contact state.
Through a micro hole in the antenna section substrate and is connected to a specific terminal of a power feeding element arranged on the back surface of the antenna section or at another position near the board. Similarly, in order to generate circular polarization,
Electromagnetic waves each having a phase difference of ± 90 ° have two pairs of high-order mode excitation probes G ₁ , G ₁ ′ and
Power is supplied to G ₂ and G ₂ ′. Higher-order mode excitation probe G ₁ ,
G ₁ ′ and G ₂ , G ₂ ′ are symmetrically arranged with respect to the central axis of the MSA in order to generate symmetrical higher-order modes, and G ₁ and G 2
₁ 'and G ₂ and G _2' is a probe to be paired as to the same phase, through a small hole in the antenna unit substrate and a ground conductor is connected to the terminal characteristics of the feeder circuit elements.

FIG. 3 is a configuration diagram of the probe F for main mode excitation and the probe G for higher-order mode excitation. The case is shown. The center pin has a function of improving the symmetry of each mode, but depending on the application, it can be put to practical use even when the center pin is not loaded.

FIG. 4 shows an example of basic characteristics of this embodiment. The pattern in the main mode (TM ₁₁ mode, eigenvalue X ₁₁ = 1.841) is
As shown in Fig. 4 (A), it covers the zenith and the area around it, and the pattern in the first higher-order mode (TM ₂₁ mode, eigenvalue X ₂₁ = 3.054) is shown in Fig. 4 (B). As shown, it covers the low elevation angle region, and the measured values (solid line) are in good agreement with each other in the design significant range including the design value (dotted line) and the radiation back direction.

FIG. 5 (A) schematically shows the distribution of magnetic lines of force in a typical higher order mode that can be used, and FIG. 5 (B) shows the set angle of the excitation probe for the higher order mode, that is, the settable angle α. Is specifically shown.

FIG. 6 shows an example of the configuration of the power supply circuit system. The power supply circuit is the sixth
As shown in FIGS. (A) to (D), a power feeding circuit having the same function is formed at a position near the back surface of the antenna section substrate and when it is directly molded on the power circuit forming board disposed at the back surface of the antenna section substrate. They are roughly classified when molding.

〔The invention's effect〕

As described above, the circularly polarized antenna according to the present invention is
The MSA for high-order mode excitation has a two-layer structure in which the MSA for main mode excitation is coaxially and closely loaded on top of the MSA.
By individually feeding power to each other or simultaneously via the phase adjusting circuit, a wide circular coverage area from the zenith region to the low elevation angle region can be covered with one circular polarization antenna.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, FIGS. 2 (A) and 2 (B) are a front view and a sectional view of this embodiment, and FIG. 3 (A).
1) to (A4) and (B1) to (B4) are arrangement diagrams of probes for main mode and higher mode excitation, and FIGS. 4 (A) and (B) are basic characteristic diagrams of this embodiment, and FIG. (A) is a diagram schematically showing a distribution of magnetic lines of force in a higher-order mode that can be used, FIG. 5 (B) is a diagram showing a spatial power supply position for each mode, and FIGS. 6 (A1) to (A4) [Fig. 4] is a diagram schematically showing a configuration method of a power feeding circuit element and a power feeding circuit. 1 ... MSA for main mode excitation, 2 ... MS for higher mode excitation
A, 3 ... Antenna board, 4 ... Center pin, 5 ... Ground conductor, 6 ... Board for feeding circuit configuration.

Claims (1)

[Claims] 1. A microstrip antenna for high-order mode excitation is co-axially loaded onto a top surface of a microstrip antenna for high-order mode excitation to form a two-layer structure. A circularly polarized microstrip antenna characterized by having characteristics.