Design of Miniature Planar Dual-Band Filter With 0â° Feed Structures

Abstract

Abstract-A novel dual-band planar filter is proposed in this paper. It is shown that the two transmission bands can be excited and designed using proposed resonators which combine different sizes of open-loop resonators. The main resonators control the low-band resonant frequency and the sub resonators control the high-band resonant frequency. With 0 • feed structures added, the frequency selectivity of the filter is greatly improved. And the proposed filter also has advantages as low insertion loss and miniature size. The measurement of the filter is in good agreement with the simulation.

A New Approach of Dual-Band Filters by Stepped Impedance Simplified Cascaded Quadruplet Resonators With Slot Coupling

“…However, these approaches may cause some problematic issues, such as extra insertion loss and poor circuit size [4,6,8]. For considerations of improving insertion losses and selectivity in both dual passbands, a dual-band filter can be designed by using cascaded quadruplet (CQ) filter with stepped impedance resonator (SIR) to obtain a high selectivity performance [9]. But, large size due to a fourth-order design has become the key problematic issue in this approach.…”

“…Unfortunately, this solution suffers from large overall size due to extra cascaded circuits. Different design procedures have been proposed in [2][3][4][5][6][7][8][9]. In [7] and another general approach [5], dual-mode dualband bandpass filters were initially reported.…”

“…Unfortunately, this solution suffers from high insertion loss and none high selectivity near the passband. Moreover, there has been improved insertion loss [9,10]. Stepped impedance resonator (SIR) can control second passband by adjusting the impedance ratio and electric lengths of SIRs.…”

“…Recently, the subject of dual-band bandpass filters is generating great interest in the design of dual-band bandpass filters with compact size and high selectivity performance [1][2][3][4][5][6][7][8][9]. Conventional microwave filter design procedures suitable for wideband passband and narrowband stopband operation have been discussed in previous studies [1].…”

Multiple Order Dual-Band Active Ring Filters With Composite Right/Left-Handed Cells

“…The basic ring resonator consists of two feeding lines that are coupled to a ring, whose electrical length is a multiple of the wavelength at the desired resonance frequency. Additionally, some modifications may be introduced in this structure in order to obtain a dual-band response in different passive configurations [19][20][21][22][23][24][25]. On the other hand, active components can be added in the ring in order to compensate the losses introduced by the transmission lines [26].…”