CN108742643B

CN108742643B - Ultra-wideband antenna suitable for human blood sugar concentration detection

Info

Publication number: CN108742643B
Application number: CN201810588305.7A
Authority: CN
Inventors: 肖夏; 胡敏
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2018-08-27
Filing date: 2018-08-27
Publication date: 2023-10-17
Anticipated expiration: 2038-08-27
Also published as: CN108742643A

Abstract

The invention relates to an ultra-wideband antenna suitable for detecting the blood sugar concentration of a human body, which is of a single-sided printing plane structure, and is printed on a substrate with the thickness of 20mm multiplied by 1.6mm, wherein a metal layer comprises a radiation metal sheet and a grounding plate; forming an inverted isosceles trapezoid blank area in the middle of the two trapezoids, and adding an inverted isosceles trapezoid metal patch with reduced equal proportion; the specific dimensions of the radiating metallic sheet were obtained by simulation. The invention has stable working characteristics in an ultra-wideband working frequency band and can effectively transmit and receive high-frequency signals.

Description

Ultra-wideband antenna suitable for human blood sugar concentration detection

Technical Field

The invention relates to an ultra-wideband antenna suitable for detecting the blood sugar concentration of a human body.

Background

Currently, the number of diabetics is increasing, and monitoring of blood glucose levels is of paramount importance. However, many existing noninvasive and minimally invasive methods do not avoid bringing physical pain and mental stress to the patient, and increase the risk of infection. The people hope to develop an accurate noninvasive blood sugar detection method.

With the rapid development of modern wireless communication technology, signal frequency band resources tend to be tense, and in order to meet the increasing military requirements and civil requirements, the working frequency bands of various microwave devices are gradually widened to high frequency. Compared with the narrow-band technology, the ultra-wideband (UWB) technology has the advantages of low power consumption, high precision, high speed, low cost, high performance and the like, and has better development space.

With the rapid development of microwave wireless technology, the applicable fields of ultra-wideband technology are continuously expanded, such as detection radar, material flaw detection, human medical field and the like. Microstrip patch antennas manufactured by the planar printing technology have compact structures and low cost, are favored by a plurality of researchers and engineering personnel after being developed and researched, and are widely explored and applied.

An antenna suitable for human microwave detection should have a stable impedance behavior at the tissue surface and should be of a sufficiently small size to be conveniently placed on various tissue surfaces, for example for blood glucose concentration detection of the earlobe tissue. A good small ultra-wideband antenna for detecting microwaves on the surface of an earlobe is provided, stable reflection characteristics are also required in a specified frequency band, the signal is received well, and a foundation is provided for later signal processing.

Disclosure of Invention

The invention provides a novel small planar printing ultra-wideband antenna which is suitable for an ultra-wideband frequency range, has stable working characteristics in a working frequency band, can effectively transmit and receive high-frequency signals, and can be applied to nondestructive detection of blood glucose concentration on the surface of earlobe tissues. The technical scheme of the invention is as follows:

a small ultra-wideband antenna for detecting the blood sugar concentration of earlobe is a single-sided printing planar structure, and is printed on a substrate with the thickness of 20mm multiplied by 1.6mm, and a metal layer comprises a radiation metal sheet and a grounding plate, and is characterized in that the radiation metal sheet is of a symmetrical structure, the periphery of the radiation metal sheet is a rectangular metal frame with the bottom connected with a feeder line, a slot is formed in the top of the rectangle, two ends of a slot are recessed into the metal frame through two right-angle metal strips, and two opposite right-angle trapezoids are connected; forming an inverted isosceles trapezoid blank area in the middle of the two trapezoids, and adding an inverted isosceles trapezoid metal patch with reduced equal proportion; the specific dimensions of the radiating metallic sheet were obtained by simulation.

Drawings

Fig. 1 is a schematic diagram of the front structure of the antenna

FIG. 2 is an S11 characteristic of the antenna

Fig. 3 transmit and receive signal waveforms for the antenna

FIG. 4 is a received signal waveform of the antenna

Detailed Description

The invention is described below with reference to the drawings and examples.

Before designing the antenna of the invention, a simple multi-layer earlobe model is constructed to build a realistic simulation environment. The initial antenna size is set in conjunction with a simple model of the earlobe tissue structure. And placing the designed transmitting antenna and receiving antenna on the skin layer surfaces at two sides of the model, and properly debugging through simulation results to obtain proper antenna structure and size.

As shown in fig. 1, the antenna has a single-sided printed planar structure, and is printed on an FR-4 type dielectric substrate with a dielectric constant of 4.4, and has an overall size of 20mm×20mm×1.6mm, and the double-layer structure of the antenna is a metal layer and a dielectric substrate layer, respectively. The metal layer is composed of a radiation metal sheet and a grounding plate. The grounding plate part consists of two symmetrical rectangular metal sheets. The radiating metallic sheet is a resonant cell that achieves the radiation of electric field energy into space. The design is a symmetrical structure, which is favorable for maintaining good directivity of the antenna and eliminating the influence caused by cross polarization, so the radiation metal sheet part is designed into a symmetrical structure. The periphery of the radiation metal sheet is a rectangular metal frame with the bottom connected with the feeder, the top of the rectangle is grooved, and two ends of the notch are recessed into the metal frame through two right-angle-shaped metal strips and connected with two opposite right-angle trapezoids. At this time, a blank area of an inverted isosceles trapezoid is formed in the middle of the two trapezoids, and an equal-proportion reduced inverted isosceles trapezoid metal patch is added into the blank area, so that the design of the whole radiation metal sheet part is formed. The radiating metal sheet is connected with a signal wire of the radio frequency connector, and the connector suitable for the antenna is an SMA joint, so that electromagnetic waves can be transmitted to the radiating metal sheet through the transmission line. Fig. 1 is a schematic diagram of the front structure of the ultra-wideband antenna. The dark portion of fig. 1 is the printed metal plane (0.035 mm copper foil). The white part of the antenna is the dielectric layer. The radiating metal plate part is calculated by cst software according to the corresponding structure. And obtaining the geometrical size parameters of the antenna through multiple times of optimization. Specific geometric parameters of the antenna were l=20mm, w=20mm, l1=1 mm, l2=2 mm, l3=9 mm, l4=2 mm, l5=7mm, l6=1 mm, l7=4 mm, w1=1 mm, w2=6.5 mm, w3=3 mm, w4=1 mm, w5=2 mm, w6=5 mm, w7=8 mm, w8=1 mm, w9=5 mm, w10=3.1 mm, w11=3 mm.

Fig. 2 is an S11 diagram of the antenna. S11 denotes return loss characteristics. Return Loss (RL) characterizes the power Loss efficiency of a transmission line port, which is the ratio of the reflected wave power to the incident wave power of the transmission line port, expressed in logarithmic form, in dB, generally

Negative values, the absolute values of which may be referred to as reflection losses. It is expressed as: rl= -20log|Γ| (dB). (Γ is the reflection coefficient)

The formula can infer that the larger the value of the return loss RL is, the more radiation power is not reflected, the better the matching performance is, and when RL is 0, the antenna is in a total reflection state, and no wave transmission from the feeder line to the antenna occurs, namely no loss of the feeder line wave occurs, and no energy is radiated. From FIG. 2, it is intuitively seen that the return loss of the antenna in the working frequency bands of 1.22-1.63GHz and 3-19.45GHz is below-10 dB, and the antenna has good matching characteristics, high standing wave ratio and high energy transfer efficiency.

Fig. 3 is a graph of input and received signal waveforms for an antenna when in operation. Fig. 4 is a waveform of a reception signal in operation. It can be seen that after reflection through the inside of the earlobe tissue, multiple waveforms appear due to multipath effects, however, the appropriate waveform can be deduced from the time delay perspective. Because the attenuation of the waveform is relatively large when operating at high frequencies. However, compared with the transmitted wave, the waveform fluctuation trend of the received wave is unchanged, the amplitude is changed only, and the amplitude change can be recovered through subsequent signal amplification processing, so that the antenna meets the actual detection requirement.

The antenna is an ultra-wideband antenna for detecting blood sugar concentration of earlobe tissues, has good performance in the whole working frequency band, and is suitable for the surfaces of the earlobe tissues and tissues with dielectric constants similar to those of human skin tissues. The electromagnetic wave transmission medium emitted by the antenna is skin tissue, and when the antenna is used for detecting the blood sugar concentration of the earlobe tissue, the antenna is closely attached to the skin surface layer to send signals.

Claims

1. The small ultra-wideband antenna for detecting the blood sugar concentration of earlobe is characterized in that the radiation metal sheet is of a symmetrical structure, the periphery of the radiation metal sheet is a rectangular metal frame with the bottom connected with the feeder line, a slot is formed in the top of the rectangle, two ends of a slot are recessed into the metal frame through two right-angle metal strips, and two opposite right-angle trapezoids are connected; forming an inverted isosceles trapezoid blank area in the middle of the two trapezoids, and adding an inverted isosceles trapezoid metal patch with reduced equal proportion; the specific dimensions of the radiating metallic sheet were obtained by simulation.