CN108742643B - An ultra-wideband antenna suitable for human blood glucose concentration detection - Google Patents

Abstract

The invention relates to an ultra-wideband antenna suitable for human body blood glucose concentration detection. It has a single-sided printed planar structure and is printed on a 20 mm × 20 mm × 1.6 mm substrate. The metal layer includes a radiation metal sheet and a ground plate. Its characteristics The radiating metal sheet has a symmetrical structure. Its periphery is a rectangular metal frame with a feeder connected to the bottom. A slot is opened at the top of the rectangle. The two ends of the slot are recessed into the metal frame through two right-angled metal strips, connecting the two Two opposite right-angled trapezoids; an inverted isosceles trapezoid-shaped blank area is formed in the middle of the two trapezoids, and a proportionally reduced inverted isosceles trapezoidal metal patch is added to it; the specific size of the radiation metal sheet is obtained through simulation. The invention has stable operating characteristics within an ultra-wideband operating frequency band and can effectively transmit and receive high-frequency signals.

Description

An ultra-wideband antenna suitable for human blood glucose concentration detection

Technical field

The invention relates to an ultra-wideband antenna suitable for detecting human blood glucose concentration.

Background technique

At present, the number of diabetic patients is growing day by day, and it is crucial to monitor blood sugar levels. However, many current non-invasive and minimally invasive methods inevitably bring physical pain and mental stress to patients, and increase the risk of infection. People are eager to develop an accurate and non-invasive method for detecting blood sugar.

With the rapid development of modern wireless communication technology, signal frequency band resources are becoming increasingly tight. In order to meet the growing military and civilian needs, the working frequency bands of various microwave devices are gradually broadened to high frequencies. Compared with narrowband technology, ultra-wideband (UWB) technology, which has many advantages such as low power consumption, high precision, high speed, low cost and high performance, has better room for development.

With the rapid development of microwave wireless technology, the applicable fields of ultra-wideband technology are constantly expanding, such as detection radar, material flaw detection, human medicine, etc. The microstrip patch antenna produced by planar printing technology has a compact structure and low cost. Since its development and research, it has been favored by many researchers and engineers and has launched extensive exploration and application development.

An antenna suitable for human body microwave detection should have stable impedance performance on the tissue surface, and should be small enough to be easily arranged on various tissue surfaces, such as for blood glucose concentration detection in earlobe tissue. A good small ultra-wideband antenna for microwave detection on the earlobe surface should also have stable reflection characteristics within the specified frequency band and good signal reception, providing a basis for later signal processing.

Contents of the invention

The invention provides a new type of small planar printed ultra-wideband antenna, which is suitable for ultra-wideband frequency range, has stable operating characteristics within the operating frequency band, and can effectively transmit and receive high-frequency signals. This antenna can be applied to blood sugar on the surface of earlobe tissue. Concentration non-destructive testing. The technical solution of the present invention is as follows:

A small ultra-broadband antenna for earlobe blood glucose concentration detection. It has a single-sided printed planar structure and is printed on a 20mm × 20mm × 1.6mm substrate. Its metal layer includes two parts: a radiation metal sheet and a ground plate. It is characterized by: The radiating metal sheet has a symmetrical structure. Its periphery is a rectangular metal frame with a feeder wire connected to the bottom. A slot is opened at the top of the rectangle. The two ends of the slot are recessed into the metal frame through two right-angled metal strips and connected to two opposite sides. A straight right-angled trapezoid is formed; an inverted isosceles trapezoid-shaped blank area is formed in the middle of the two trapezoids, and a proportionally reduced inverted isosceles trapezoidal metal patch is added to it; the specific size of the radiation metal sheet is obtained through simulation.

Description of the drawings

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

Figure 2 S11 characteristic curve of the antenna

Figure 3 The transmitting and receiving signal waveforms of the antenna

Figure 4 The received signal waveform of the antenna

Detailed ways

The present invention will be described below in conjunction with the drawings and examples.

Before designing the antenna of the present invention, a simple multi-layer earlobe model is first constructed to build a realistic simulation environment. Combined with a simple model of the earlobe tissue structure, the initial antenna size is set. The designed transmitting antenna and receiving antenna are placed on the surface of the skin layer on both sides of the model, and the appropriate antenna structure and size are obtained through appropriate debugging through simulation results.

As shown in Figure 1, this antenna has a single-sided printed planar structure, printed on an FR-4 dielectric substrate with a dielectric constant of 4.4. The overall size is 20mm × 20mm × 1.6mm. The double-layer structure of this antenna is made of metal. layer and dielectric substrate layer. The metal layer consists of two parts: a radiating metal sheet and a ground plate. The ground plate part is composed of two symmetrical rectangular metal pieces. The radiating metal sheet is a resonant unit that radiates electric field energy into space. The symmetrical structure is designed to help maintain good directivity of the antenna and eliminate the influence of cross-polarization. Therefore, the radiating metal sheet part is designed to have a symmetrical structure. The periphery of the radiating metal sheet is a rectangular metal frame with a feeder wire connected to the bottom. A slot is cut at the top of the rectangle. The two ends of the slot are recessed into the metal frame through two right-angled metal strips and connected to two opposite right-angled trapezoids. . At this time, an inverted isosceles trapezoid-shaped blank area is formed in the middle of the two trapezoids, and a proportionally reduced inverted isosceles trapezoidal metal patch is added to it to complete the design of the entire radiating metal sheet part. The radiation metal piece is connected to the signal line of the RF connector. The connector suitable for this antenna is an SMA connector, which can transmit electromagnetic waves from the transmission line to the radiation metal piece. Figure 1 is a schematic diagram of the front structure of this ultra-wideband antenna. The dark part in Figure 1 is the printed metal plane (0.035mm copper foil). The white part of the antenna is the dielectric layer. The radiation metal sheet part is calculated by cst software according to the corresponding structure. After many optimizations, the geometric size parameters of the antenna are obtained. The specific geometric size parameters of the antenna are L=20mm, W=20mm, L1=1mm, L2=2mm, L3=9mm, L4=2mm, L5=7mm, L6=1mm, L7=4mm, W1=1mm, W2=6.5 mm, W3＝3mm, W4＝1mm, W5＝2mm, W6＝5mm, W7＝8mm, W8＝1mm, W9＝5mm, W10＝3.1mm, W11＝3mm.

Figure 2 is the S11 diagram of the antenna. S11 represents the return loss characteristics. Return Loss (RL) represents the power loss efficiency of the transmission line port. It is the ratio of the reflected wave power to the incident wave power of the transmission line port. It is expressed in logarithmic form. The unit is dB, usually

Negative value, its absolute value can be called reflection loss. Its expression is: RL=-20log|Γ|(dB). (Γ is reflection coefficient)

It can be inferred from the formula that the larger the value of return loss RL, the more unreflected radiated power is, and the better the matching. When RL is 0, it means that the antenna is in a state of total reflection, and no wave transmission from the feeder to the antenna occurs. , that is, no feeder wave loss occurs and energy is not radiated. From Figure 2, we can intuitively see that the return loss of the antenna in the operating frequency bands 1.22-1.63GHz and 3-19.45GHz is below -10dB. It has good matching characteristics, high standing wave ratio, and high energy transfer efficiency.

Figure 3 shows the input and received signal waveforms when the antenna is working. Figure 4 shows the received signal waveform during operation. However, it can be seen that after the signal is reflected inside the earlobe tissue, multiple waveforms appear due to the multipath effect. However, the appropriate waveform can be found from the perspective of time delay. Because it works under high frequency conditions, the attenuation of the waveform is relatively large. However, compared with the transmitted wave, the waveform fluctuation trend of the received wave remains unchanged, and only the amplitude changes. The amplitude change can be restored through subsequent signal amplification processing, so the antenna meets the actual detection needs.

This antenna is an ultra-wideband antenna suitable for detecting blood glucose concentration in earlobe tissue. It has good performance in the entire working frequency band and is suitable for the surface of earlobe tissue and some tissues with dielectric constants similar to human skin tissue. The electromagnetic wave transmission medium emitted by the antenna is skin tissue. When the antenna is used to detect blood glucose concentration in earlobe tissue, it should be closely attached to the surface of the skin to receive and receive signals.

Claims (1)

1. A small ultra-wideband antenna for earlobe blood glucose concentration detection. Its metal layer is a single-sided printed plane structure, printed on a 20mm×20mm×1.6mm substrate. The metal layer includes two parts: a radiation metal sheet and a ground plate. The ground plate part is composed of two rectangular metal sheets symmetrically arranged on both sides of the feeder. It is characterized in that the radiating metal sheet has a symmetrical structure, and its periphery is a rectangular metal frame with the bottom connected to the feeder, with a slot on the top of the rectangle. Both ends of the slot are recessed into the metal frame through two right-angled metal strips, connecting two opposite right-angled trapezoids; an inverted isosceles trapezoid-shaped blank area is formed in the middle of the two trapezoids, and equal proportions are added to it. A reduced inverted isosceles trapezoidal metal patch; the specific size of the radiation metal patch is obtained through simulation.