What is an Acoustic Coupler?

In a microwave system, it is often necessary to divide one microwave power into several channels in proportion, which is a problem of power allocation. The components that realize this function are called power distribution components or couplers, which mainly include: directional couplers, power distributors and various microwave branch devices.

Coupler

In a microwave system, it is often necessary to divide one microwave power into several channels in proportion, which is a problem of power allocation. The element that accomplishes this is called a power distribution element.

Principle analogy:

The cabbage fields on the north and south sides of Lao Zhang are divided into 3 parts. Lao Zhang hopes that through a one-time water channel modification, each part will get a small part of the water flow from the main waterway. Show.

Use a multimeter to judge the quality, as shown in Figure 3. Disconnect the power at the input terminal, and measure 1, 2 with R × 1k file.

Compose switch circuit

When the input signal ui is at a low level, the transistor V1 is in an off state, the current of the light-emitting diode in the photocoupler B1 is approximately zero, and the resistance between the output terminals Q11 and Q12 is very large, which is equivalent to the switch opening; At a high level, v1 is turned on, and the light-emitting diode in B1 is turned on, and the resistance between Q11 and Q12 becomes smaller, which is equivalent to the switch on. This circuit is in a high-level on state because Ui is low when the switch is off. Similarly, when there is no signal (Ui is low level), the switch is turned on, so it is in a low level conducting state.

2. Make up a logic circuit

The circuit is an AND gate logic circuit. its

Table 2 Technical specifications of the coupler

project	specification
	5dB	7dB	10dB	15dB	20dB
Insertion loss	1.7dB	1.2dB	0.7dB	0.3dB	0.3dB
VSW standing wave ratio	1.4
Coupling loss	5dB	7dB	10dB	15dB	20dB
Input power	15W
Connector (Interface) Type	N-Female

The isolator is also called a reverser. There is almost no attenuation when the electromagnetic wave passes through it in the forward direction, and the attenuation is great when it passes in the reverse direction. Commonly used isolators are harmonic

Coupler

Vibration and field shift.

Coupler Resonant Isolator

Due to the anisotropy of ferrite, the left and right circularly polarized rotating magnetic fields that have a left and right spiral relationship with the Hi direction under the constant magnetic field Hi have different magnetic permeability (set to - and + respectively) . At a certain point on the microwave transmission line containing ferrite materials, a left-handed magnetic field is transmitted in the + z direction, and a right-handed magnetic field is transmitted in the -z direction. Both transmit the same distance, but the corresponding magnetic permeability is different, so the left-right magnetic field Different phase speeds produce different phase shifts. This is the irreversibility of ferrite phase shifts. On the other hand, ferrites have a ferromagnetic resonance effect and a resonance absorption effect of a circularly polarized magnetic field.

The so-called ferromagnetic resonance effect of a ferrite means that when the working frequency of the magnetic field is equal to the resonance angular frequency 0 of the ferrite, the absorption of the microwave energy by the ferrite reaches a maximum value. For circularly polarized magnetic fields, left and right-handed polarized magnetic fields have different magnetic permeability, so that they also have different absorption characteristics.

For the right-handed polarized magnetic field transmitted in the reverse direction, the magnetic permeability is +, which has a ferromagnetic resonance effect, and for the left-handed magnetic field transmitted in the forward direction, the magnetic permeability is -, which does not have the ferromagnetic resonance characteristic. This is the resonance effect of a circularly polarized magnetic field. Ferrite resonance isolators are made using this characteristic of ferrite.

Coupler Field Shift Isolator

Field-shift isolators are made based on the different field-shift effects of ferrites on the wave modes transmitted in two directions.

It adds an attenuator on the side of the ferrite sheet. Due to the difference in the fields generated by the two directions of transmission, the electric field of the transmitted wave in the forward direction (-z direction) is biased to the side without the attenuator, and in the reverse direction ( + z direction) The electric field of the transmitted wave is deflected to one side of the attenuator, thus achieving the isolation function with small forward attenuation and large reverse attenuation, as shown in Figure 5-32.

Because of its small size, light weight, simple structure and wide operating frequency band, the field-shift isolator is widely used in low-power applications.

Coupler related terminology: ^[1]

1.	acoustic coupler Acoustic coupler
2.	access coupler Access coupler
3.	broadband directional coupler Broadband directional coupler
4.	coupler, token ring interface (TIC) Token Ring Interface Coupler
5.	coupler, star Star coupler
6.	coupler, fused fiber Fusion Spliced Fiber Optic Coupler
7.	coupler, broadband directional Broadband directional coupler
8.	coupler, acoustic Acoustic coupler
9.	coupler Coupler
10.	directional coupler Directional coupler
11.	fused fiber coupler Fusion Spliced Fiber Optic Coupler
12.	token-ring interface coupler (TIC) Token Ring Interface Coupler
13.	Token Ring Interface Coupler Token Ring Interface Coupler