A compact dual-mode BPF base on interdigital structure

Abstract

Based on shorten wavelength effect and lowpass characteristic of interdigital structure, a compact dual-mode narrow band BPF (band-pass filter) is proposed in the paper. This filter combines interdigital structure with conventional dual-mode BPF, and takes full advantage of the blank center of conventional dual-mode loop resonator. The shorten wavelength effect and low-pass characteristic of interdigital structure is analyzed first of all, and then a structure of dual-mode narrow band BPF using interdigital structure is proposed, followed by simulation and optimization. At last, the novel filter is fabricated and the measurement results show that the proposed filter has favorable application value due to its compact size and good performance.

Miniaturized Multiband EBG Reflector Using DICPW Structure for Wireless Communication Systems

“…The connection is characterized by a capacitive connection at the transmission line's end, which generates a large slow wave on the transmission line and causes the electrical length (θt) to differ from the transmission line's physical length. Consequently, it is possible to reduce the physical size of an EBG unit cell from /2 to /8 at 1.8 GHz [26], [31], [46][47][48][49], and the connecting pin between the transmission line and ground plane can remove surface waves on the structure and induce an inductance (L). In the EBG unit cell structure, it is discovered that jXL is lower than -jXC; hence, the total capacitive circuit (Ct) impacts the entire resonance frequency.…”

“…The electrical lengths θa0, θa1, θa2 and θa3 correspond to the first, second, third, and fourth resonant frequencies, respectively. Moreover, f0 through f3 represent the first through fourth resonance frequencies, respectively [46][47][48].…”

“…Generally, the traditional CPW structure creates the capacitances between the transmission line and the ground, which are extremely modest and do not impact the fundamental frequency resonance with harmonic frequency. By raising the capacitance value between the transmission line and ground using the interdigital technique, also known as ICPW [45][46][47][48], the resonance frequency shift of the harmonic frequencies can be regulated according to the desired frequency range, with no change in the resonant frequency of the fundamental frequency, and a dispersion range without surface waves covering the required frequency range can be generated. In addition, raising the capacitance value using ICPW approach may reduce the size of the unit cell to less than /4, and when the unit cell is arranged in an array to be used as an antenna reflector, it can improve the gain compared to a conventional reflector.…”

Dual Band Square Planar Dipole Antennas with Interdigital Capacitors for Base Stations

“…This section presents the design of the dipole antenna with embedded interdigital lines [18][19][20], as the structure shown in Fig. 1.…”

A Compact Multiband BPF Using Step-impedance Resonators with Interdigital Capacitors

“…In addition, the SIRs with capacitive load at the end were proposed for dual band [13] and triple band [14] responses, resulting in further size reduction from λ/2 to λ/4. Whereas, the technique using interdigital capacitor seems to have higher capacitance than capacitive load, therefore, novel microstrip interdigital bandstop filters [15], dual-mode BPF based on interdigital [16] were presented, resulting in further size reduction.…”