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Guided Wave Propagation and Transmission Lines
Published in Mike Golio, Commercial Wireless Circuits and Components Handbook, 2018
W.R. Deal, V. Radisic, Y. Qian, T. Itoh
Coplanar Waveguide (CPW), shown in Fig. 12.6b, consists of a signal line and two ground planes on a dielectric slab with metallization on one side. For a given substrate, characteristic impedance is determined by the signal line width, s, and the two gaps, w1 and w2. This structure often demonstrates better dispersion characteristics than microstrip. Additionally, three terminal devices are easily integrated into this uniplanar transmission line that requires no vias for grounding. For this reason, parasitics are lower than microstrip making CPW a good choice for high frequency operation where this is a primary design concern.
Planar Transmission Lines
Published in S. Raghavan, ®, 2019
Coplanar waveguide (CPW), proposed by C.P. Wen in 1969, is another basic transmission line where all the conductors are situated on one side of the dielectric substrate. It consists of a strip conductor separated by a slot on either side from the two adjacent ground planes as shown in Figure 2.13a. Its electrical and magnetic field distributions are shown in Figure 2.13b.
On-Body Low-Profile Compact AMC-Integrated Wideband Antenna for Body Area Network Applications
Published in IETE Technical Review, 2023
The antenna feed structure is calculated in Equations (1)–(7). The width of the CPW strip (W), gap (g), thickness (h), and dielectric constant (ϵr) of the substrate determine the effective dielectric constant (ϵeff) and characteristic impedance (Z0) of the CPW line. The effective dielectric constant and characteristic impedance (Z0) of a coplanar waveguide on a dielectric substrate of finite thickness [31, 32] are given by k1 and k2 can be defined from the W, g and h parameters.
A Flexible Multiband Antenna for Biomedical Telemetry
Published in IETE Journal of Research, 2023
Abdullah Al-Sehemi, Ahmed Al-Ghamdi, Nikolay Dishovsky, Gabriela Atanasova, Nikolay Atanasov
Figure 1(a) illustrates the procedure used to construct the proposed flexible multiband antenna. The design is based on a monopole fed by a coplanar waveguide (CPW) transmission line. This design was chosen because of its advantages of a single-layer fabrication process and wide bandwidth. As a first step, a CPW having 50-Ω impedance over 0.5–6 GHz (Figure 1) was design. Next, a monopole antenna was designed and optimized to operate in 0.75–0.96 GHz and 2.06–2.54 GHz frequency bands. The main reason to choose the monopole as a radiating element is that it exhibits an omnidirectional radiation pattern and simple structure which are highly preferable in biomedical telemetry applications. The length of the monopole was adjusted according to the general design guideline that the lowest resonance is determined when the length of the monopole, is approximately λeff/4 [22], where λeff (λeff = λair/√(εrμr)) is the effective wavelength at 0.850 GHz. As observed from Figure 1(c), two peaks appear over the frequency band at about 0.85 and 2.27 GHz with bandwidths covering MBAN and most of the ISM bands. Moreover, the antenna suffers from a relatively large footprint, the overall dimension is 26 mm × 75.5 mm × 2 mm.
A modified proposed capacitance model for step structure capacitive RF MEMS switch by incorporating fringing field effects
Published in International Journal of Electronics, 2020
K. Girija Sravani, Koushik Guha, K. Srinivasa Rao
The proposed step-down structure RF MEMS switch consists of a thick substrate made up of single-crystal silicon. The substrate is subjected to the oxidation process to form a SiO2 layer which prevents the passage of leakage currents into the substrate during signal transmission. A coplanar waveguide made up of gold is taken over the SiO2 layer which is used as the transmission line for the switch. The central conductor of the CPW is acting as the signal line and other two conductors which are on either side of the signal line acts as the ground planes and the RF signal is fed across these signal and ground planes. A thin dielectric layer placed over the signal line to develop capacitance between beam and signal line. The beam is suspended over the signal line with the help of meanders to regulate the passing of RF signal as shown in Figure 2.