A multi-order spiral antenna suitable for superconducting terahertz mixers

Abstract

This invention belongs to the field of wireless communication technology, specifically relating to a multi-stage spiral antenna using a superconducting terahertz mixer. The invention includes a first spiral antenna, a second spiral antenna, a third spiral antenna, a fourth spiral antenna, and a superconducting Josephson junction terahertz mixer. The first and second spiral antennas have the same number of spiral turns, N, and are symmetrically arranged about the diagonal. The third and fourth spiral antennas have the same number of spiral turns, K, and are symmetrically arranged about the diagonal; K is greater than N. The first and third spiral antennas are connected and each is connected to one end of the superconducting Josephson junction terahertz mixer. The second and fourth spiral antennas are connected and each is connected to the other end of the superconducting Josephson junction terahertz mixer. The superconducting Josephson junction terahertz mixer is located at the center of the multi-stage spiral antenna.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically relating to a multi-order spiral antenna suitable for superconducting terahertz mixers. Background Technology

[0002] Terahertz waves, with their abundant bandwidth, make terahertz communication a powerful option for addressing the data rate and capacity limitations of current wireless communication systems. Compared to microwaves and millimeter waves, terahertz waves have shorter wavelengths, which is beneficial for achieving high spatial resolution and also brings the advantages of compactness and lightness for system integration. However, due to limited transmit power and severe atmospheric attenuation at terahertz frequencies, ultrasensitive heterodyne receivers are urgently needed for effective signal detection. Cryogenic superconducting thermionic radiometric mixers and superconductor-insulator-superconductor mixers are the most sensitive downconverters to date. However, these cryogenic superconducting devices require cooling to liquid helium temperatures (4.3K) or lower, necessitating large and expensive cryogenic facilities, thus limiting their applications primarily to astronomical observations. For terahertz wireless communication systems, high-temperature superconducting Josephson junction mixers offer a combination of advantages, including high sensitivity, wide bandwidth, low local oscillator power, and lower cryogenic cost (compared to cryogenic superconducting mixers), making them an ideal choice for receiver front-ends.

[0003] Currently reported high-temperature superconducting mixers can be categorized into fundamental frequency (FFM) and higher harmonic frequency (HFFM) mixers based on their operating modes. The former typically exhibits higher mixing conversion gain but requires an expensive Asia-Pacific Hertz (APH) source to provide a local oscillator pump at a frequency similar to the received signal. In contrast, the latter uses a microwave local oscillator, thus reducing system cost. However, they suffer from considerable performance degradation associated with higher harmonic wavenumbers. At higher frequencies, the drawbacks of both operating modes become more pronounced. In such cases, lower harmonic frequency (HFFM) mixers offer a very good trade-off between cost and performance in Asia-Pacific Hertz receiver systems.

[0004] To unlock the potential of high-temperature superconducting mixers, high-performance on-chip antennas are needed to effectively couple Asia-Pacific Hertzian radiation into the Josephson junction. Planar log-periodic antennas and helical antennas exhibit stable radiation characteristics over a wide bandwidth. However, these complementary structures typically have an input impedance of approximately 80 Ω on the substrate, far exceeding the normal-state resistance of the Josephson junction, which is only a few ohms. This results in low coupling efficiency between the antenna and the device when applied to high-temperature superconducting Josephson junction mixers. Other reported on-chip antennas, such as loop antennas and dual-slot antennas, are much more efficient in coupling radiation, but they are limited to narrowband operation and are not suitable for broadband or multiband applications. Summary of the Invention

[0005] The purpose of this invention is to address the lack of suitable multi-band antennas for current low-order harmonic superconducting terahertz mixers, and to propose a multi-order spiral antenna suitable for superconducting terahertz mixers.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A multi-stage spiral antenna suitable for a superconducting terahertz mixer includes a first spiral antenna, a second spiral antenna, a third spiral antenna, a fourth spiral antenna, and a superconducting Josephson junction terahertz mixer. The first and second spiral antennas have the same number of spiral turns, N, and are symmetrically arranged about the diagonal. The third and fourth spiral antennas have the same number of spiral turns, K, and are symmetrically arranged about the diagonal; K is greater than N. The first and third spiral antennas are connected and respectively connected to one end of the superconducting Josephson junction terahertz mixer. The second and fourth spiral antennas are connected and respectively connected to the other end of the superconducting Josephson junction terahertz mixer. The superconducting Josephson junction terahertz mixer is located at the center of the multi-stage spiral antennas.

[0008] Furthermore, as a preferred embodiment of the present invention, K is 5 and N is 4.

[0009] As a further preferred embodiment of the present invention, the impedance of the superconducting Josephson junction terahertz mixer is 10Ω.

[0010] The multi-order spiral antenna applicable to superconducting terahertz mixers described in this invention has the following technical advantages compared with existing technologies:

[0011] (1) This invention designs a suitable multi-band antenna for low-impedance low-order harmonic superconducting terahertz mixers, enabling simultaneous reception of local oscillator pump and detection signals at multiple resonant frequencies without the need for additional isolation circuits, thus simplifying the mixing circuit.

[0012] (2) The present invention embeds a low-impedance superconducting terahertz mixer at an appropriate position in the antenna to achieve low impedance matching without affecting the antenna performance. Attached Figure Description

[0013] Figure 1 This is a structural diagram of a multi-stage spiral antenna with an embedded low-impedance superconducting mixer according to an embodiment of the present invention.

[0014] Figure 2 This is a schematic diagram of the parameters of a multi-stage spiral antenna with an embedded low-impedance superconducting mixer according to an embodiment of the present invention.

[0015] Figure 3 This is a simulation diagram of the reflection coefficient at the low-impedance superconducting mixer in the multi-stage spiral antenna of this invention embodiment;

[0016] Figure 4 Simulation diagram of the far-field radiation direction of a multi-order spiral antenna with an embedded low-impedance superconducting mixer according to an embodiment of the present invention at different resonant frequencies;

[0017] The attached figures are labeled as follows: 1-1, first helical antenna; 1-2, second helical antenna; 2-1, third helical antenna; 2-2, fourth helical antenna; 3, superconducting Josephson junction terahertz mixer. Detailed Implementation

[0018] The present invention will be further explained in detail below with reference to the accompanying drawings, so that those skilled in the art can better understand and implement the present invention. However, the following examples are only used to explain the present invention and are not intended to limit the present invention.

[0019] like Figure 1 As shown, a multi-stage spiral antenna suitable for a superconducting terahertz mixer includes a first spiral antenna 1-1, a second spiral antenna 1-2, a third spiral antenna 2-1, a fourth spiral antenna 2-2, and a superconducting Josephson junction terahertz mixer 3. The first spiral antenna 1-1 and the second spiral antenna 1-2 have the same number of spiral turns (4) and are symmetrically arranged about the diagonal. The third spiral antenna 2-1 and the fourth spiral antenna 2-2 have the same number of spiral turns (5) and are symmetrically arranged about the diagonal. The first spiral antenna 1-1 and the third spiral antenna 2-1 are connected and each is connected to one end of the superconducting Josephson junction terahertz mixer 3. The second spiral antenna 1-2 and the fourth spiral antenna 2-2 are connected and each is connected to the other end of the superconducting Josephson junction terahertz mixer 3. The superconducting Josephson junction terahertz mixer 3 is located at the center of the multi-stage spiral antenna. The impedance of the superconducting Josephson junction terahertz mixer 3 is 10Ω.

[0020] The first helical antenna 1-1 and the second helical antenna 1-2 form one pair, and the third helical antenna 2-1 and the fourth helical antenna 2-2 form another pair. The width, spacing, number of turns, and total length of the two pairs of helical antennas can be unequal. They operate in resonant mode, and the structural parameters are adjusted according to the frequency required for the multi-band. The total length of the two pairs of helical antennas is related to the resonant frequency of the antennas. This invention is applicable to other arbitrarily low-impedance terahertz devices.

[0021] In practical applications, when a multi-stage spiral antenna with an integrated superconducting Josephson junction terahertz mixer 3 is placed on a thick dielectric substrate, its surface wave effect can be eliminated by placing a silicon super-hemispherical lens or an electromagnetic bandgap structure on the back side.

[0022] In practical implementation, in the CST simulation software, the antenna material is set as an ideal conductor, placed on a magnesium oxide (relative permittivity of 9.6) substrate, and the superconducting Josephson junction terahertz mixer 3 is represented by a discrete port of 10Ω. For example... Figure 2 As shown, when the antenna parameters are l = 170 μm, w1 = w2 = 4 μm, c1 = c2 = 4 μm, g1 = 6 μm, g2 = 4 μm, s1 = 10 μm, s2 = 6 μm, and the number of turns of the first spiral antenna 1-1 and the second spiral antenna 1-2 is 4, and the number of turns of the third spiral antenna 2-1 and the fourth spiral antenna 2-2 is 5, the reflection coefficient at point 3 of the superconducting Josephson junction terahertz mixer is as follows: Figure 3 As shown, the resonant frequency bands achieve multi-band resonance at four centers: 137 GHz, 179 GHz, 208 GHz, and 373 GHz. The corresponding far-field radiation patterns at their center frequencies are shown in the figure. Figure 4 As shown, the directional coefficients are 7.91 dBi, 8.23 ​​dBi, 8.54 dBi and 8.17 dBi, respectively.

[0023] The purpose of this invention is to propose a multi-order spiral antenna suitable for low-order harmonic superconducting terahertz mixers; the local oscillator pump and detection signals can be directly received and mixed by the on-chip antenna without the need for additional isolation circuits, thus completing the integration of the on-chip multi-band antenna and the high-temperature superconducting Josephson junction and simplifying the mixing circuit.

[0024] The specific implementation schemes described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific implementation schemes of the present invention and are not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A multi-order spiral antenna suitable for superconducting terahertz mixers, characterized in that, The system includes a first helical antenna (1-1), a second helical antenna (1-2), a third helical antenna (2-1), a fourth helical antenna (2-2), and a superconducting Josephson junction terahertz mixer (3). The first helical antenna (1-1) and the second helical antenna (1-2) have the same number of helical turns, N, and are symmetrically arranged about the diagonal. The third helical antenna (2-1) and the fourth helical antenna (2-2) have the same number of helical turns, K, and are symmetrically arranged about the diagonal. K is greater than N. The first helical antenna (1-1) and the third helical antenna (2-1) are connected and are respectively connected to one end of the superconducting Josephson junction terahertz mixer (3). The second helical antenna (1-2) and the fourth helical antenna (2-2) are connected and are respectively connected to the other end of the superconducting Josephson junction terahertz mixer (3). The superconducting Josephson junction terahertz mixer (3) is located at the center of the multi-stage helical antenna.

2. A multi-order spiral antenna suitable for a superconducting terahertz mixer according to claim 1, characterized in that, K is 5 and N is 4.

3. A multi-order spiral antenna suitable for a superconducting terahertz mixer according to claim 1, characterized in that, The impedance of the superconducting Josephson junction terahertz mixer (3) is 10Ω.

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