A Directional Bridge Based on Coupling Capacitance

Abstract

The present invention proposes a directional bridge based on coupling capacitance, including: a power dividing circuit and a coaxial balun; the power dividing circuit includes a first resistor, a first capacitor, a second resistor and a third resistor connected in series ; The first port is connected to the third port through the first resistor and the first capacitor, and the third port is also connected to the ground potential through the second resistor and the third resistor; the coaxial balun includes a coaxial line and a magnetic ring, The magnetic ring is sleeved on the coaxial line, the coaxial line includes an outer conductor and an inner conductor, the first end of the outer conductor is connected to the common end of the second resistor and the third resistor, and the first end of the inner conductor is connected to the first Port, the first end of the outer conductor and the first end of the inner conductor together form a coaxial balanced end; the second end of the inner conductor is an unbalanced end, connected to the second port, and the second end of the outer conductor is grounded. The present invention makes the operating frequency lower under the premise of ensuring that the high-frequency characteristics are not affected.

Description

technical field [0001] The invention relates to the field of microwaves, in particular to a directional bridge based on coupling capacitance. Background technique [0002] Directional bridges are widely used in phase shifting, power synthesis and distribution, power sampling, directional coupling, directional detection, and dynamic monitoring of signal sources. They are key components in microwave systems and test and measurement. Microwave systems and microwave measuring instruments face the current demand for broadband use, and also have higher requirements for the ultra-wideband performance of the directional bridge. The most typical signal directional separation scheme in general applications is a directional coupler based on a tapered coupling line, which can achieve multi-octave high-directional signal directional separation, but the electrical length is longer at low frequencies, and the length of the coupling line is limited. It is difficult to achieve a relatively ...

AI Technical Summary

Problems solved by technology

[0004] It can be seen that the performance of the bridge is greatly affected by the fixed-ratio power-dividing characteristics of the power dividing circuit and the balance characteristics of the balun. Since the low-frequency characteristics of the balun are limited by the magnetic permeability of the magnetic core and its own volume, as the lower limit frequency decreases, the balance of the two circuits The balance characteristics of the output amplitude and phase deteriorate rapidly, and the two signals at the coupling end of the resistance power are unbalanced, and the isolation and directivity deteriorate seriously.

The simple balun broadband design and the existing resistive power divider circuit design scheme are difficult to broaden the low frequency lower limit while maintaining high frequency performance, so its frequency band adaptability is not particularly ideal

[0005] Therefore, it is difficult for existing bridges to take into account the needs of low-frequency applications of megahertz and below and high-frequency applications above 10GHz

Images