Low Band Coaxial Impedance Conversion Why

2 Balance converter 2 balance converter is also called U-shaped balance converter, as shown in Figure 3, when the half-wave oscillator antenna (input impedance is 300 ohms) is connected with a coaxial line of 75 ohms, the impedance of the two does not match, so a U-shaped balance converter must be installed between them. As can be seen from Figure 3, the impedance of the answer to the ground of the feed points A and B is 300 2 = 150 ohms, and the signal is transmitted from the main feed cable to point A and is divided into two ways, which are respectively supplied to the load segments on the left and right sides of the oscillator. Since the wave path difference between the two feed points A and B is 2.

Therefore, the power supply of the two feed points A and B is equal in size and opposite in direction, so as to achieve the purpose of balanced transformation. Looking at the impedance, since the impedance to the ground at points A and B is 150 ohms, then after being synthesized together, the impedance of point A should be the parallel value of the two feed points, that is, 150 2 = 75 ohms, so the impedance is also matched.

There is this kind of plug is too pure, there is an impedance converter inside, and one end is a flat feeder of 300 ohms. The other end is a closed-circuit plug, where the components are sold, you can have it, but the virtual model is used less often.

Can it be used on antenna oscillators? Will there be any loss when I install it?

1. There is no polarization charge in the conductor, the polarization intensity is zero and the internal electric field is zero. Only dielectrics with an infinite dielectric constant have this property.

2. The permittivity (also known as the permittivity) is shown as a surface fiber, =r* 0, 0 is the absolute permittivity of the vacuum, 0=. It is important to emphasize that the value of the dielectric constant of a material is closely related to the frequency of the test.

When a capacitor plate is filled with a substance with a dielectric constant of , the capacitance becomes r times larger. Dielectrics have the property of making a space larger or smaller than its actual size. For example, when a dielectric material is placed between two electric charges, it is instructed to reduce the force acting between them, as if they were moved away.

Don't think about it, there is no point in asking such questions.

A lot of our troubles are our own.

The ratio of the primary impedance to the secondary impedance of the transformer is equal to the square of the ratio of the number of turns on the primary side to the number of turns on the secondary side.

1. Analyze the no-load circuit on the primary side and draw the equivalent circuit on the no-load side.

2. Load on the secondary side.

The circuit is analyzed and the equivalent circuit on the secondary side is drawn.

3. Pass.

The electromagnetic induction between the primary and secondary sides is analyzed, and the impedance of the secondary side is converted to the primary side.

4. Draw the total primary side equivalent circuit including the original no-load primary side and the converted secondary side.

5. Vector analysis is usually used.

It is hypothesized that the ratio of turns of the primary and secondary of the transformer is n:1, and according to the characteristics of the transformer, the secondary voltage is 1 n of the primary and the current is n times that of the primary.

Primary impedance = primary voltage and primary current.

Secondary impedance = secondary voltage Secondary current = (1 n) primary voltage (n primary current) = [1 (nn)] primary impedance. Or that the primary impedance = (nn) secondary impedance.

This shows that the impedance of each coil of the transformer is proportional to the square of the number of coil turns. Taking advantage of this feature, the impedance can be converted by using coils of different turns of the transformer. The simplest, is the TV antenna, the impedance is 300 when using the flat feeder, the antenna input of the TV is 75, and an impedance conversion socket must be used, which is a ferrite core of 2:

1 transformer, 300 and 75 are impedance matched.

The characteristic impedance of a coaxial wire depends mainly on the ratio of its inner and outer conductor radius, and also on the filling material between the inner and outer conductors. The maximum cut-off frequency is related to its overall size. If in its transmission band, the filler material is air, then the ratio of the inner and outer diameters is 7:

At 16 o'clock, the impedance is close to 50 ohms.

One is related to the size of the construction, and the other is related to the use of materials.

Impedance is a physical quantity expressed when resistance, capacitance, and inductance have an obstructive effect on electrical signals in a circuit, and it is a general term for the combination of these three independent resistances, capacitive impedances, and inductive reactances. Because the transistor is a nonlinear component, it has the function of converting impedance through different circuit combinations (connections).

In circuits with resistors, inductors, and capacitors, the impedance that acts as a barrier to the current is called. The impedance is commonly represented by z and is a complex number, the real part is called resistance, and the imaginary part is called reactance. (The obstructive effect of the capacitor on the alternating current in the circuit is called capacitive reactance, and the obstructive effect of the inductor on the alternating current in the circuit is called the inductive reactance.)

The impeding effect of capacitance and inductance on alternating current in a circuit is collectively referred to as reactance. The unit of impedance is ohms.

In practice, the impedance of a port network is equal to the terminal voltage of the circuit divided by the current passing through. Because the transistor has the function of converting and regulating voltage and current, it can naturally be expressed in the change of impedance (i.e., the ratio of voltage to current).

In fact, in addition to the transistor, there are also some other components or circuits that also have the role of impedance conversion.

Because the measurement with an oscilloscope is equivalent to borrowing the circuit into parallel, which will affect the voltage or current of the signal loop itself, so the impedance matching problem must be considered in order to measure the real signal.

The load resistance is fixed, but the impedance value does not match the power supply, in order to obtain the maximum power, the transformer conversion impedance can be matched with the power supply. If the power supply impedance is Zo and the load impedance is Z2, a transformer is added between them, and the primary impedance of the transformer Z1=K Z2, as long as the transformer ratio K is appropriately selected, Z1 can be changed to make it equal to ZO, so as to achieve impedance matching. Maximizing the power of the load.

No, the equivalent impedance of the load as seen from the input.

It's not impedance matching.