Wideband balun based on microstrip line-slot structure

Abstract

The invention discloses a wideband balun based on a microstrip line-slot structure. The wideband balun comprises an input end microstrip line conduction band and two output end microstrip line conduction bands, which are arranged on the upper surface of a dielectric substrate, wherein two sections of U-shaped slot lines and a metal ground plate are arranged on the lower surface of the dielectric substrate; the input end microstrip line conduction band and the middle portions of the two sections of U-shaped slot lines form a vertical three-dimensional cross structure, and the input end microstrip line conduction band is parallel to internal slot lines; the two output end microstrip line conduction bands are respectively arranged on two sides of the input end microstrip line conduction band, extend from the edge of the dielectric substrate to the input end microstrip line conduction band and have tail ends folded to be L-shaped; the folded portions of the two output end microstrip line conduction bands are parallel to the external slot lines of the U-shaped slot lines, and the output end microstrip line conduction bands on the two sides are distributed in central symmetry about the midpoint of the input end microstrip line conduction band. The wideband balun has the advantages of compact structure, low insertion loss, good matching characteristic and the like, and facilitates broadband and miniaturization development of wireless communication.

Description

technical field [0001] The invention relates to the technical field of microwave passive devices, in particular to a broadband balun based on a novel interconnection structure. Background technique [0002] The balun is a balanced unbalanced converter, which can realize the equal-amplitude and anti-phase distribution of power and the function of impedance matching. Its application fields are very wide. For example, in the antenna field, for a differential antenna, a balun is needed to convert an unbalanced signal into a balanced signal to feed it. At present, the most common signal transmission line in microwave integrated circuits is microstrip line, which transmits unbalanced signals, while coplanar waveguide and coplanar stripline are single-sided transmission lines, which are small in size, easy to integrate, and easy to realize with microstrip structure. Features such as broadband interconnection structure. Based on this background, we use the microstrip line-slot lin...

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Problems solved by technology

[0004] Literature 1 (ZhanXu, and LeonardMacEachern, OptimumDesignofWidebandCompensatedandUncompensatedMarchandBalunsWithStepTransformers, IEEE Transaction on Microwave Theory Tech., 2009,57,(8): 2064-2071), by using the equivalent circuit of Marchand balun, by analyzing its chained scattering matrix, cascading multi-step impedance, so as to design a broadband balun with equal ripple in the passband, But this balun is larger in size and has higher insertion loss

[0005] Literature 2 (PengWu, YongZhang, Yu-LiangDong, and QinZhang, AnovelKa-bandplanarbalunusingmicrostrip-CPS-microstriptransition, IEEEMicrowaveWirelessCompon. Lett. ,2011,21,(3):136-138) used the interconnection structure of two symmetrical microstrip lines-coplanar striplines to realize a broadband balun, but the size of the balun is relatively large and the structure is relatively complicated

[0006] Document 3 (JinShao, RongguoZhou, ChangChen, Xiao-HuaWang, HyoungsooKim, and HualiangZhang, Designofawidebandbalunusingparallelstrips, IEEEMicrowaveWirelessCompon. Lett. ,2013,23,(3):125-127) used a phase shifter to realize a wideband balun, which has better port matching characteristics, but the size of the balun is larger

[0007] To sum up, the wideband balun in the prior art is designed based on the traditional Marchand balun in a cascaded manner, the impedance matching is not easy to achieve, and its size is large and the structure is complex

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