Balun bandpass filter based on multilayer substrate integrated waveguide power divider

Abstract

A compact multilayer substrate integrated waveguide (SIW) balun bandpass filter is proposed. A 1808 reverse phase characteristic between the input/output ports can be easily achieved by the middle metal-ground of the SIW power divider. Four inductive posts are added to the multilayer SIW power divider to realise a passband. Good in-band balance performance (amplitude and phase imbalance are less than 0.35 dB and 28) over the passband are achieved for the balun bandpass filter.Introduction: As one of most important RF front-end functional passive devices, the balun bandpass filter integrating balun and bandpass filter is a necessary component for converting a balanced signal into an unbalanced one for a specified bandpass characteristic in RF/microwave communication systems. In the past few years, several techniques have been proposed to design narrow/dual-band, and wideband balun bandpass filters [1][2][3][4]. The characteristics of balun and bandpass filtering can be easily realised in these filter structures. However, the application of these filters is limited because the optimisation of the in-band balun performances is not convenient to realise.In the authors' previous works [5,6], two planar substrate integrated waveguide (SIW) magic-T structures with wide band and simple design based on E-plane power dividers were proposed. Compared with the T/Y-junction planar SIW power divider structures [7], the size reduction of the circuits is almost 50 and 75%, respectively. In this Letter, a compact balun bandpass filter with four inductive posts based on the multilayer SIW power divider [5] is designed. A high-order passband (centre frequency 12.5 GHz, bandwidth 4.8%) with high selectivity and extended stopband for the balun filter can be achieved.

A Novel Power Divider Integrated With Siw and DGS Technology

“…In addition, the proposed band-pass power divider is relatively compact, it is smaller than other two SIW and HMSIW based band-pass power dividers in [29] and [30]. Although, the size of power divider in [27] and [31] is smaller than our proposed one, these two power dividers are based on microstrip line which means they will suffer from high radiation loss when they are used in high frequency applications such as in microwave and millimeter wave circuits.…”

“…And the group delay is quite smooth with variation of less than 0.1 ns which indicates that the proposed power divider gets a linear phase. Table 2 illustrates the performance comparison between the proposed power divider and some reported power dividers integrated with filers [27][28][29][30][31].…”

A Substrate Integrated Waveguide to Substrate Integrated Coaxial Line Transition

“…The selection of the operation frequency bandwidth should keep the SIW operating in the fundamental mode TE 10 . In other words, the operation frequency of the SIW must satisfy the condition: f TE 10 < Figure 5.…”

“…At present, many SIW passive components have been studied, such as filters [10][11][12], power dividers [13], phase shifters [14,15], diplexers [16], antennas [17,18], and so on. However, active SIW circuits are hardly ever used.…”

“…However, there are no papers that report such a transition to the best of our knowledge. In this paper, a novel SIW-to-SICL transition based on the SIW 3 dB power divider (PD) [10] and SIW 180 • phase shifter (PS) [15] is proposed. The SIW-to-SICL transition with centre operating frequency of 7 GHz is constructed, fabricated, and measured.…”