JPH0260083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a dual-frequency microstrip antenna that can be used at two frequencies.

[Technical background of the invention]

A conventional dual frequency microstrip antenna is constructed as shown in FIGS. 1 and 2. Figure 1 is a perspective view, and Figure 2 is a perspective view.
The figure is shown in side view.

In both FIGS. 1 and 2, a center post 1 is intended to support a radiating strip conductor 2 of radius a through an air layer of thickness d.
A ground conductor plate 3 is placed between the radiating strip conductor 2 and the air layer. A diode loading post 4 is arranged at a distance _r3 from the axis of the center post 1. A diode 5 is loaded on the diode loading post 4.

Further, a power feeding post 6 having a diameter of 2rf is arranged at a distance r ₁ from the axis of the center post 1 . A power supply line 7 is connected to the power supply post 6, and the radiating strip conductor 2 is supplied with power by this power supply line 7.

In this way, by turning the diode 5 on or off at two desired frequencies using the diode 5, etc., and changing the loading reactance of the equivalent parasitic diode loading post 4 to 0 and ∞, The impedance was matched at two frequencies.

For example, the design was such that at frequency = ₁ , impedance matching can be achieved with diode 5 in the on state (loading reactance = 0), and at frequency = ₂ , impedance matching can be achieved with the diode in the off state (loading reactance = ∞).

[Problems with background technology]

Therefore, conventional dual-frequency microstrip antennas not only require a control circuit to turn on and off the diode depending on the frequency used, but also require a power supply, driver cables, etc. As a result, the configuration became complicated and inconvenient. Further, in this conventional dual frequency microstrip antenna, the operating frequency is switched by turning on and off a diode, and two desired frequencies cannot be shared at the same time.

[Purpose of the invention]

This invention was made in consideration of the above-mentioned circumstances, and is a dual-frequency common microstrip that can be shared by two frequencies simultaneously without requiring additional cables, power supplies, or control circuits. The purpose is to provide a flexible antenna.

[Summary of the invention]

The dual-frequency microstrip antenna according to the present invention can be used at two different frequencies by providing a non-feeding post as well as a feeding post, and loading the non-feeding post with a reactance that changes with frequency. This is what I did.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the dual-frequency microstrip antenna of the present invention will be described below with reference to the drawings. FIGS. 3 and 4 are diagrams showing the configuration of one embodiment. FIG. 3 is a perspective view, and FIG. 4 is a side view, which correspond to FIGS. 1 and 2, respectively.

In FIGS. 3 and 4, to avoid duplication, the same parts as in FIGS.
I will focus on the parts that differ from the diagram.

In the embodiment shown in FIGS. 3 and 4,
In addition to a center post 1 and a feeding post 6 for supporting a radiation strip conductor 2 on an air layer having a thickness d, a parasitic loading post 8 is provided, and a reactance element 9 is loaded on this post. This loading post 8 is loaded with a reactance element 9, and by utilizing its resonance and anti-resonance phenomena, its loading reactance is 0 and ∞ for each of two frequencies.
It has a frequency characteristic such that This loading post 8 is arranged at a distance r ₂ from the center post 1.

The reactance element 9 is constituted by a reactance line having a branch path that provides an impedance value such that it is short-circuited for one frequency transmitted through the power supply post 6 and open for other frequencies, as shown in FIG. 5, for example. be done. The terminals 91 and 92 are connected to the loading post 8, and the terminals 93 and 94 and the terminal 9
5,96 is opened.

In the embodiment shown in Figs. 3 and 4, the dimensional conditions are a = 10 cm (radius of the radiating strip conductor 2) d = 1.2 cm (thickness of the air layer) r ₁ = 4 cm (center post 1 and power supply (distance between each axis of post 6) r ₂ = 5 cm (distance between each axis of center post 1 and loading post 8) rf = 0.05 cm (radius of power feeding post 6), and reactance shown in Figure 5. In element 9, a line with characteristic impedance R _c = 50Ω is used, and lengths L ₁ = 28.23 cm, L ₂ = 28.23 cm, and L ₃ respectively.
= 6.44cm, the loading reactance is
₁ = 858MHz becomes 0, ₂ = 798MHz becomes ∞.

FIG. 6 is a diagram showing the input impedance characteristics in this case.

As is clear from Fig. 6, matching is achieved at the two frequencies, ₁ = 858MHz _{and 2} = 798MHz. The microstrip antenna in this embodiment can be used at frequencies ₁ and ₂ simultaneously.

FIG. 7 and FIG. 8 are the second embodiments of this invention, respectively.
This is an example of the following. FIG. 7 is a perspective view, and FIG. 8 is a side view. They correspond to FIGS. 3 and 4, respectively.

This second embodiment is provided with two parasitic loading posts 8a and 8b. That is, the loading post 8a has a spacing r ₃ from the center post 1, and the loading post 8b has a spacing r ₂ from the center post 1.
The reactance element 10 is further loaded onto the loading post 8a.

The reactance element 10 is composed of a reactance line, for example, as shown in FIG. That terminal 1
1 and 12 are connected to the loading post 8a, and the terminal 1
3, 14 and 15, 16 are open.

In this second example, each dimensional condition is a
= 10 cm (radius of radiating strip conductor 2) d = 1.2 cm (thickness of air layer) r ₁ = 4 cm (distance between each axis of center post 1 and feeder post 6) r ₂ = 1 cm (center post 1 and The distance between the axes of the loading post 8b) _r3 = 5 cm (the distance between the axes of the center post 1 and the loading post 8a) rf = 0.05 cm (radius of the power feeding post 6), and in the reactance element 10, When using a line with characteristic impedance R _c = 50Ω and setting the lengths L ₁ = 28.13cm, L ₂ = 28.13cm, and L ₃ = 6.48cm, the loading reactance is ₁ = 860M.
It becomes 0 at Hz, and becomes ∞ at ₂ = 800MHz.

FIG. 10 is a diagram showing the input impedance characteristics in this case. In this case as well, it can be seen that the two frequencies ₁ = 860MHz _{and 2} = 800MHz are matched. The microstrip antenna of this second embodiment can be used simultaneously at frequencies ₁ and ₂ .

In the above two embodiments, the number of parasitic loading posts is one or two, but good characteristics can generally be obtained by using a plurality of them.

Furthermore, it goes without saying that the shape of the radiating strip conductor is not limited to a circular shape, and a dielectric layer may be provided between the radiating strip conductor 2 and the ground conductor plate 3. In this case, center post 1
It doesn't have to be there.

〔Effect of the invention〕

As described above, according to the dual-frequency microstrip antenna of the present invention, a power source is additionally provided.
It can be easily used at two different frequencies at the same time without requiring any control circuits, cables, etc., and has great practical effects.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams explaining the configuration of a conventional dual-frequency microstrip antenna;
4 and 4 are diagrams illustrating the configuration of an embodiment of a dual-frequency microstrip antenna according to the present invention, and FIG. 5 is a diagram illustrating the reactance element shown in FIGS. 3 and 4. , Figure 6 shows the third
The input impedance characteristic diagrams of the dual frequency microstrip antenna shown in FIG. 4 and FIGS. 7 and 8 illustrate other embodiments of the dual frequency microstrip antenna according to the present invention Figure 9 is a diagram explaining the reactance element shown in Figures 7 and 8, and Figure 10 is a diagram explaining the reactance element shown in Figures 7 and 8.
FIG. 9 is an input impedance characteristic diagram of the dual-frequency microstrip antenna shown in FIGS. 1... Center post, 2... Radiation strip conductor, 3... Ground conductor plate, 6... Power supply post, 7...
Power supply line, 8, 8a, 8b...Loading post, 9, 1
0...Reactance element.

Claims (1)

[Claims] 1. A radiating strip conductor disposed on a ground conductor via a dielectric layer or an air layer, a power feeding post that feeds power to this radiating strip conductor, and a radiating strip conductor located between the ground conductor and the radiating strip conductor and between the radiating strip conductor and the radiating strip conductor. A parasitic loading post disposed at a position facing the power feeding post about the center, and a short-circuit for one frequency that is connected to the parasitic loading post and transmits the power feeding post, and an open circuit for other frequencies. 1. A dual-frequency microstrip antenna, comprising: a reactance element having a branch path that provides such an impedance value to the loading post, and is configured to achieve impedance matching at two frequencies at the same time.