# Design of a Filtering Power Divider with Simple Symmetric Structure Using Stubs
###### Abstract  
A power divider (PD) with a wide stopband and simple symmetric structure using open- and short-ended stubs is analyzed and implemented in this paper. In the proposed power divider, for the first time, the output resistor is divided into two sections and open- and short-ended stubs are used between the resistors. The incorporated open- and short-ended stubs have resulted in a controllable bandwidth for the proposed PD, which resulted in 40% of the fractional bandwidth considering 3 dB attenuation of insertion loss. The proposed PD operates at 2 GHz, which shows more than 20 dB attenuation for the return and isolation losses. In addition, the obtained insertion loss at the operating frequency is approximately 0.3 dB, which shows a minor loss, and also, high isolation is achieved in the device. Moreover, 20 dB and 30 dB attenuation levels have been achieved for second and third harmonics. The results show high performance for the proposed power divider.  
power divider; microstrip; open-ended; short-ended; resonator; radio frequency; 2 GHz; harmonics +
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in this work, but the insertion losses in the pass bands are high and the suppression band is not wide enough.  
In [24], metamaterial and ring resonators were used to design a tri-band power divider for different applications. However, this divider size is rather large, and bandwidths of operating frequencies are narrow, such that the shifted frequencies in the fabrication process degraded the performance of the divider at operating frequencies. Open stubs, radial stubs, and rectangular resonators have been used to design a WPD (Wilkinson power divider) for GSM applications [25]. A Gysel divider based on composite transmission lines has been designed in [26]. The proposed transmission lines in [25] can be used to control the three operating bandwidths of the divider, but the divider size is rather large.  
A generalized architecture for the power divider was presented in [27], using open stubs, radial lines, and a multi-stage structure. The dividers presented in [27] show dual- or triple-band operation, but the device size is larger than the typical one. A divider with open stubs and tapered resonators was presented [28] to obtain a wide suppression band. The divider designed in [28] was used for antenna array applications, but the size of this divider was rather large. A multi-band divider was presented in [29] using open stubs and multi-mode resonators, which achieved a wide suppression band. Furthermore, the open stubs in [29] were used to amend the isolation of the divider.  
Recently, new design techniques have been presented to design wideband power dividers [30; 31; 32]. In [30], coupled lines and the multi-section technique were used to achieve dual-band and wideband operations. Furthermore, in [31; 32], a multi-section structure and analytic design method were used to design power dividers with wideband and dual-band operations. Coupled lines and open stubs were used in [33] to design filtering response dividers with frequency reconfigurable ability. However, in [33], a wide suppression band was not achieved.  
In all of the mentioned works, open- and short-ended stubs and other resonators were utilized for miniaturization or to provide a suppression band. However, in the proposed work, the open- and short-ended stubs are not only used to provide the suppression band, but are also utilized to control the operating bandwidth with a very simple structure. Furthermore, in the presented structure, two resistors are employed to obtain high isolation. Although a very simple structure is designed for the proposed WPD, high performances, such as more than 20 dB attenuation for the return loss and isolation, are achieved. In addition, the obtained insertion loss at the operating frequency is approximately 0.3 dB, which shows a minor loss, and also, high isolation is achieved in the device. Moreover, 20 dB and 30 dB attenuation levels have been achieved for second and third harmonics.