Capacitive Electromagnetic Antenna (CEM Antenna)

Abstract

The present invention discloses a capacitive electromagnetic (CEM) antenna for use in generating and / or detecting time-varying electromagnetic fields over a wide frequency range. The antenna includes an electrical circuit comprising a support structure (e.g., a printed circuit board) and a signal feed mechanism that electrically connects an input signal to a plurality of single-layer capacitors mounted on the support structure and arranged in a specific geometric configuration. The single-layer capacitors are composed of two conductive plates separated by a dielectric material, and each capacitor has two input terminals, a ground terminal and a signal terminal, connected to each conductive plate. The capacitors, acting as radiating elements, are fed with signals via two terminals: the ground terminal of the feed mechanism connected to the capacitor's ground, and the signal terminal of the feed mechanism connected to the capacitor's signal terminal.

Description

[Technical Field]

[0001] The present invention relates to a capacitive electromagnetic antenna, which will be abbreviated as a "CEM antenna" hereinafter. [Background technology]

[0002] One of the most widely used types of antennas in high frequency applications is the microstrip patch antenna. One of the drawbacks of this type of antenna is that, under its optimum operating conditions, the length of a microstrip antenna is approximately equal to one-quarter of the wavelength of the signal being transmitted or received. For transmitting antennas, this factor limits the electromagnetic energy per unit area of ​​the antenna.

[0003] Similarly, receiving antennas are limited in the amount of energy received per unit area of ​​the antenna, as are other types of antennas. Furthermore, at optimum operating parameters, microstrip patch antennas, like other types of antennas, have a radiation resistance on the order of approximately 102 Ω, which further limits the electromagnetic energy transmitted from individual elements in the array. Summary of the Invention

[0004] The proposed CEM antenna is characterized by an array of single-layer capacitors as antenna elements arranged in a specific geometric configuration on a support surface, such as a PCB (printed circuit board), containing a feed mechanism through which the individual single-layer capacitor elements are coupled to a signal to be transmitted or to an electronic circuit that extracts information from a received signal. The CEM antenna overcomes two drawbacks of microstrip patch antennas by:

[0005] First, the energy emitted from a particular radiating element (in this case a single-layer capacitor element) depends on the capacitance, the frequency of the signal, and the design and manufacturing constraints of those capacitors and their associated circuits (e.g., stray inductance and resistance), but not on the size of the capacitor. Thus, the energy per unit area of ​​the antenna is not limited.

[0006] Second, the resistance of the radiating element in a CEM antenna (which is given by the capacitive reactance) can be as low as 0.01 Ω, limited only by the design and manufacturing constraints of the capacitor element (i.e., factors including, but not limited to, parasitic inductance and resistance). [Brief explanation of the drawings]

[0007] [Figure 1a] FIG. 1a shows an example of a single-layer capacitor. [Figure 1b] Figure 1b is a circuit diagram of a single-layer capacitor. [Figure 2] Figure 2 shows the spatial distribution of electromagnetic energy radiated by an individual single-layer capacitor. [Figure 3] Figure 3 shows a simple implementation of a CEM antenna. [Figure 4] Figure 4 shows the spatial distribution of the electromagnetic field radiated by the CEM antenna. DETAILED DESCRIPTION OF THE INVENTION

[0008] Figure 1a shows an example of a single layer capacitor, and Figure 1b shows a circuit diagram of a single layer capacitor. Because single layer capacitors can take many different shapes, the drawings in Figures 1a and 1b show the most identifiable parts of a single layer capacitor in relation to the physical capacitor and the circuit diagram, so that parts can be easily identified when the two illustration methods are used interchangeably.

[0009] Figure 2 shows the spatial distribution of electromagnetic energy radiated from an individual single-layer capacitor, an example of which is shown in Figures 1a and 1b. In this graph, the axis labeled FS represents "field strength" and the axis labeled DEG represents "angle" in degrees.

[0010] Figure 3 shows a simple implementation of a CEM antenna. This CEM antenna consists of a 3 x 6 array of radiating elements (single-layer capacitors) mounted on a support structure (e.g., a printed circuit board) and a feed mechanism consisting of a simple transmission line feeding each of the single-layer capacitor elements. The single-layer capacitor is depicted as its schematic symbol, showing the orientation of the plates relative to each other and to the support structure and feed point.

[0011] Figure 4 shows the spatial distribution of the electromagnetic field radiated by the CEM antenna.

[0012] The present invention relates to a capacitive electromagnetic antenna (CEM antenna) that has an array of single-layer capacitor radiating elements mounted on a support structure (one example of which is a printed circuit board). The CEM antenna has a clearly defined feed mechanism for each capacitor in the array. The single-layer capacitor has two terminals, one designated as ground and the other designated as a signal.

[0013] An example of a single-layer capacitor is shown in Figure 1a, and its circuit diagram is shown in Figure 1b. These single-layer capacitors are geometrically arranged in a specific manner with respect to the spatial orientation and terminals (i.e., the plate designated as ground) of capacitor plates 1 and 2 shown in Figures 1a and 1b to produce a desired radiation pattern or to be sensitive to electric fields with a particular spatial and / or temporal distribution. The radiation pattern shown in Figure 4 is a superposition of the radiation patterns of individual single-layer capacitors in an array such as that shown in Figure 2.

[0014] An example of a single-layer capacitor, shown in Figures 1a and 1b, consists of two parallel conductive plates 1 and 2 of defined surface area, with a dielectric material 5 sandwiched between plates 1 and 2. Extending from each of plates 1 and 2 are two connecting leads 3 and 4, one of which functions as ground and the other as signal. These leads serve as the signal input for a single element when the array is operating as a transmitting antenna, and as the signal output for a single element when the array is operating as a receiving antenna.

[0015] Applying a sinusoidal signal to the single-layer capacitor via leads 3 and 4 produces the radiation pattern shown in Figure 2. In this graph, the vertical axis labeled FS represents "field strength," and the horizontal axis labeled DEG represents "angle" in degrees. This angle is the angle at which the field is measured relative to the single-layer capacitor, which is centered at the origin (0,0,0) of a Cartesian coordinate system. The field is measured on a circular path with a specific radius from the origin, ranging from 0 degrees to 360 degrees in the (x,z) plane, defined as the z-axis.

[0016] The power available from a single element (single-layer capacitor) depends on the capacitive reactance of the individual capacitor at a particular frequency (signal frequency). An example of an implementation is shown in Figure 3. This example consists of a 3 x 6 array of single-layer capacitors mounted on a support surface 6. Each single-layer capacitor is fed via two sets of transmission lines 7. One set of transmission lines 7 is ground and the other set is the signal or live connection. These are electrically connected in parallel to each other to the leads 3 and 4 of each single-layer capacitor. The two sets of transmission lines 7 are connected to an external signal source, one set to the signal source's ground and the other to the signal terminals of the signal source.

[0017] The electromagnetic field strength at any point away from the CEM antenna is the vector sum of the field strengths due to the individual single-layer capacitor elements, resulting in the radiation pattern shown in Figure 4. In this graph, the vertical axis labeled FS represents "field strength," as measured in a circular path of a particular radius from the origin (0,0,0) in a Cartesian coordinate system on the (x,z) plane, over an angular range from 0 to 360 degrees. This angle is measured relative to the CEM antenna, which is positioned on the (x,y) plane and has its center at the origin (0,0,0) of the Cartesian coordinate system. In this case, the 0-degree axis is along the z-axis, represented as "DEG" on the horizontal axis of the graph.

[0018] The above assumptions assume that the wavelength of the input signal is much larger than the length L of the CEM antenna, and is at least 20 times larger than the length L of the CEM antenna (where L represents the length of the path that the current travels from the signal source to the single element farthest from the signal source). The relationship between the wavelength (λ) of the signal and the length L of the CEM antenna is given by the following approximate formula, where L represents the length of the path that the current travels from the signal source to the single element farthest from the signal source: JPEG2026508346000002.jpg17126

[0019] Similarly, to maximize the power available from a CEM antenna or to direct the energy in a particular direction (beamforming), phase altering circuits can be used in feeding each element or specific, predetermined groups of elements. In this way, maximum output power can be achieved by feeding signals of the same phase to all elements or groups of elements. On the other hand, beamforming can achieve a specific beamforming pattern by providing specific, predetermined signal phase angles to each element or group of elements.

Claims

1. a support structure; a signal supply mechanism; and an electrical circuit including an array of single layer capacitors geometrically arranged on the support structure; Generate specific radiation patterns or increase sensitivity to specific signals or signals with specific spatial and / or temporal configurations; Capacitive Electromagnetic (CEM) Antenna.

2. 10. The capacitive electromagnetic (CEM) antenna of claim 1, wherein each single-layer capacitor comprises two conductive plates separated by a dielectric material, each of said single-layer capacitors having two input terminals, a ground terminal and a signal terminal connected to each conductive plate.

3. 3. The capacitive electromagnetic (CEM) antenna of claim 2, wherein the single layer capacitor as a radiating element is supplied with a signal through the two terminals, the ground terminal being supplied by a supply mechanism connected to the ground of the single layer capacitor, and the signal terminal being supplied by a supply mechanism connected to the signal terminal of the single layer capacitor.

4. 3. The capacitive electromagnetic (CEM) antenna of claim 2, wherein the signal feed mechanism electrically connects an input signal to each of the plurality of single-layer capacitors, the ground terminal being fed by a feed mechanism connected to the ground of the single-layer capacitor, and the signal terminal being fed by a feed mechanism connected to the signal terminal of the single-layer capacitor.

5. 4. A capacitive electromagnetic (CEM) antenna as claimed in claim 3, wherein an electromagnetic field is generated orthogonal to a current in the single layer capacitor forming the basis of a transmitter, and a current is generated in the single layer capacitor by an electromagnetic field orthogonal to a current path in the single layer capacitor forming the basis of a receiver.

6. A capacitive electromagnetic (CEM) antenna according to any one of claims 1 to 5, wherein the array of single layer capacitors is arranged on the support structure to form a transmitter or receiver.

7. The capacitive electromagnetic (CEM) antenna of claim 1 , wherein the support structure is a printed circuit board (PCB).

8. The capacitive electromagnetic (CEM) antenna of claim 1 , wherein the particular radiation pattern is achieved by the geometric placement of the single layer capacitor on the support structure.

9. 10. The capacitive electromagnetic (CEM) antenna of claim 1, wherein a particular sensitivity to signals is achieved by the geometric placement of the single layer capacitor on the support structure.

10. 10. The capacitive electromagnetic (CEM) antenna of claim 1, wherein the energy radiated by a particular radiating element depends on capacitance, frequency of the signal, and design and manufacturing constraints of the single-layer capacitor and circuitry associated with the single-layer capacitor, including but not limited to parasitic inductance and parasitic resistance.

11. 10. A method of generating and / or detecting time-varying electromagnetic fields over a wide frequency range using a capacitive electromagnetic (CEM) antenna according to claim 1.

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