Compact Microwave Components with Harmonic Suppression Based on Artificial Transmission Lines

Abstract

In this paper, compact microwave components, including a Wilkinson power divider and a 3 dB branch-line coupler based on artificial transmission lines (ATLs) with harmonic suppression, are presented. A section ATL is consisted of microstrip stepped impedance transmission lines and a microstrip interdigital capacitor. To achieve a compact size, the stepped impedance transmission lines are folded into a right-angled triangle shape. For the ATL, the interdigital capacitor is used to suppress harmonics. By employing two sections of 70.7 Ω ATLs with a right-angled triangle shape to replace conventional transmission lines, the proposed power divider working at 0.9 GHz achieves a size miniaturization with the 58.8% area of a conventional case. In addition, the power divider has good harmonic suppression performance. In the design of a branch-line coupler, two pairs of ATLs with 50 Ω and 35.4 Ω are utilized. For 50 Ω ATLs, the ATLs are designed to a right-angled triangle shape. Meanwhile, to obtain a more compact size, these 35.4 Ω ATLs are modified to an isosceles trapezoid shape. The proposed branch-line coupler operating at 0.9 GHz accounts for merely 33.4% of a coupler adopting conventional microstrip transmission lines. Moreover, the harmonics of a branch-line coupler are suppressed effectively as well. Finally, measured results of the proposed Wilkinson power divider and branch-line coupler display good performance and agree with their simulated results well.

Electromagnetic band gap based in Peano fractal geometry for harmonic suppression

“…3 These parameters interfere directly with the signal-to-noise ratio in communication systems. 4 A conventional alternative to reduce propagation of harmonics in circuits design for communications in microwave range is the use of filters. However, this technique can increase the complexity and dimensions of the printed circuit.…”

“…1 In addition, other techniques are proposed in the literature for harmonic suppression, for example, photonic band gap, electromagnetic band gap (EBG), defective ground structure (DGS) with different shapes (Dumbbell, U and V Slot, Spiral), open stubs, inductively slow-wave transmission lines, compact micro resonant cell strips (CMSRC), slotted filtering antenna, and square sing slotted antenna with rectangular slots in the ground plane. 2,[4][5][6][7][8][9][10][11] However, other approaches are reported, such as a compact low pass filter, 12 spur-line filter, 13 microstrip patch antenna integrated with complementary split ring resonator etched in the ground plane, 14 frequency selective rasorber, 15 single-layer microstripfed patch antenna. 16 Thus, some of these techniques use fractal geometry in device design, as the application of DGS fractal array in a rectangular microstrip patch antenna (RMPA) to act as filters.…”

“…16 Thus, some of these techniques use fractal geometry in device design, as the application of DGS fractal array in a rectangular microstrip patch antenna (RMPA) to act as filters. 4,7,10 In this paper, we present a new model of rectangular microstrip antenna with air slots (RMAS) inserted into the substrate, obtained from an EBG structure with fractal geometry based on Peano curves (PCs). The main objective of this work is to combine EBG tchniques with fractal distribution to suppress higher-order harmonics, attenuating, and/or avoiding the propagation of degenerate modes.…”

“…In this context, the suppression of these harmonics becomes of fundamental importance for the good performance of the system, especially regarding the antennas resonance range, the width of these ranges, frequency selectivity, and gain response 3 . These parameters interfere directly with the signal‐to‐noise ratio in communication systems 4 …”

“…However, other approaches are reported, such as a compact low pass filter, 12 spur‐line filter, 13 microstrip patch antenna integrated with complementary split ring resonator etched in the ground plane, 14 frequency selective rasorber, 15 single‐layer microstrip‐fed patch antenna 16 . Thus, some of these techniques use fractal geometry in device design, as the application of DGS fractal array in a rectangular microstrip patch antenna (RMPA) to act as filters 4,7,10 …”