On the Fundamental Resonance of Slot Loop Antenna Inductively Fed by a Coplanar Waveguide

Abstract

The fundamental resonance of a slot loop antenna inductively fed by a coplanar waveguide (CPW) is examined and designed for operation. The input matching at the fundamental resonance is achieved by using a pair of shunt inductors realized by folded thin strips placed across the coupled slotlines of the feeding CPW. Besides, the higher-order resonances, or the harmonics, are suppressed effectively by narrowing the protruded signal trace of the CPW as well as by adding the shunt inductor pair. For verification, a prototype antenna is designed and fabricated. The simulated and measured results agree excellently. The antenna is well matched at its fundamental resonance (2.5 GHz), and the wideband harmonic suppression of at least up to 20 GHz is achieved. The radiation pattern at resonance is slot-like, and the measured peak gain is 3.6 dBi with a radiation efficiency of 80%.Index Terms-Coplanar waveguides, resonant-type antennas, slot antennas, slot loop antennas.

Harmonic Suppressed Slot Loop Antenna Fed by Coplanar Waveguide

“…The corresponding resonant frequencies are , respectively, where is the fundamental resonant frequency. Since the fundamental resonance is hardly excited without adding additional tuning structures [19], the first three resonant frequencies that can be excited would be , and . In the following design, is chosen to be 0.8 GHz, thus the first three harmonic frequencies excited are 2.4, 4.0, and 5.6 GHz.…”

Study of harmonic suppression using defected ground structure for OSRR antenna

“…Due to this, the matching circuit becomes bulky and more insertion losses are introduced into the system . Therefore, harmonic suppression antenna designs with filter circuits are preferred . In order to achieve the harmonic suppression at higher order modes, several techniques have been proposed like adding extra stub, various shaped slot antennas like meandered, T–shaped structures and the Photonic band gap (PBG) technique .…”

“…In order to achieve the harmonic suppression at higher order modes, several techniques have been proposed like adding extra stub, various shaped slot antennas like meandered, T–shaped structures and the Photonic band gap (PBG) technique . However, these techniques have either complicated structures or occupy larger areas, which make them undesirable . Compared to the above techniques, the defected ground structures (DGS) technique , helps in obtaining the harmonic suppression in the wider bandwidth with simple structures.…”

“…Most of the existing harmonic suppression antennas are implemented with larger size. Compactness is an important parameter in antenna domain.…”

A modified CPW-fed slot dipole antenna with wideband harmonic suppression

“…The harmonics can be effectively suppressed by adding different slot stubs along the CPW feed-line [1], [2]; however, additional insertion losses are inevitably introduced by them. In [3], the fundamental resonance of the slot loop antenna inductively fed by a CPW is investigated, in which by placing a pair of folded thin strips across the coupled slotlines of the CPW feed-line and narrowing the protruded signal line of the CPW, good impedance matching at the fundamental resonance and large reflection coefficients at harmonics are achieved. The antenna shows wideband harmonic suppression up to at least 8f 0 , where f 0 is the fundamental resonant frequency.…”