Distributed elements have been used to model some parts of the presented transitions. It could be argued that, being electrically short, such pieces could have been modelled as lumped components, thus redounding in further model simplification. However, there are several reasons to follow the transmission line approach: 1) as will be shown in the model assessment section, model transmission lines can be around 30–35 degrees in electrical length at the highest considered frequency, which indicates that distributed behaviour is relevant; 2) on the other hand, as seen in Figure 2, transmission line lengths depend on the iris dimension and can be directly obtained from the geometry of the transition; and 3) all commercial microwave circuit CAD tools implement transmission line elements which can be used straight away to implement the proposed model. It could also be argued that the changes in the cross section will excite higher order modes and produce fringing effects that are not accounted for in the proposed model, but this is not the case due to the fact that cross section variation between different sections is small enough and the energy in higher order modes is negligible.
In amplified use of hybrid, monolithic microwave and millimeter wave circuits the choice of transmission line is coplanarwaveguide (CPW). It is the most striking alternative to conventional used microstrip line and stripline due to its uniplanar geometry. It consist of a centre strip with two ground planes located in the same plane [1-2] i.e., on the same surface of dielectric slab as shown in Figure.1. The ground plane being on the same surface lends itself to easy mounting of circuitelements and active devices; Drilling of holes or slots through the substrate is not needed [3-6]. CPW structures are commonly used in high-speed circuits and interconnect. It offers several advantages over microstrip which are summarized in Table 1. The use of CPW in the design of circuit components and transmission lines is not yet widespread. One reason for this is due to the lack of analytical data pertaining to the characteristics of CPW [7-8].
Considering accurately model the R and L in the equivalent circuit, Tran et al.  proposed a classical RLGC equivalent circuit to describe CPW in MIS behavior, by extracting RLCG eﬀects from the measurement. To have the extractions match the models in R and L , additional elements were added to the serial terms of the model to account for the eddy currents in the conductive substrate and conductor. As related in , the parameters accounting for the eddy current do not have any intrinsic physical meaning. Besides the R and L , the capacitance C is modeled as the Si substrate capacitance in parallel with the capacitance of the SiO 2 layer.
Abstract—This paper presents a coplanar composite right-left handed zeroth-order resonator (CRLH CPW ZOR) and a coplanar composite right-left handed transmission line (CRLH CPW TL). These devices are realized using an elementary cell designed in a coplanarwaveguide configuration on alumina substrate. Additional lumped elements are carried out with an interdigital series capacitor and a short-circuited stub inductor as a shunt. The CRLH CPW ZOR is fabricated and analyzed using equivalent circuit modeling and three dimensional finite element method. The proposed devices are fabricated and measured. The resonator has a measured insertion loss of 2.7 dB and a return loss better than 13 dB. The length of the proposed device is only 5.2 mm; this very small size compared with a traditional half wave resonator, shows the interest of this kind of approach.
Low loss rates provided by superconducting coplanar waveguides (CPW) and CPW res- onators are relevant for microwave applications which require quantum-scale noise levels and high sensitivity, such as mutual kinetic inductance detectors , parametric ampliﬁers , and qubit devices based on Josephson junctions , electron spins in quantum dots , and NV-centers . Transmission line (TL) coupling allows for implementing rela- tively weak resonator-feedline coupling strengths without signiﬁcant oﬀ-resonant pertur- bations to the propagating modes in the feedline CPW. Owing to this property and ben- eﬁting from their simplicity, notch-port couplers are extensively used in frequency mul- tiplexing schemes , where a large number of CPW resonators of diﬀerent frequencies are coupled to a single feedline. The geometric design of such resonators determines the resonant frequencies of their modes, loss rates and coupling coeﬃcients of these modes to other elements of the circuit. 3D electromagnetic simulation software provides excellent means for complete characterization of such structures by ﬁnite element analysis. How- ever, in the case of simple structures, analytical formulas can be devised that are invaluable for engineering of large multi-pixel resonator arrays.
The laminate used for microwave components have surface roughness typically in the range of several micrometers. Based on optical profilometer measurements we have seen that the surface is uneven which is suspected to affect the dielectric breakdown characteristics of any protective thin film. Hence the patterned surface of the CPW is mechanically polished. Polishing is done in two steps, first with fine carbon particles powder which removes the microstructures but leaves the scratches on the surface. Scratches are reduced by polishing with diamond paste on nylon cloth. The signal conductor of the CPW is then covered with a dielectric (SU- 8) to avoid the short circuit or arcing while actuating the beams, therefore increasing the device reliability. SU-8 is reported to have good dielectric strength. This is done by spin coating two layers of SU-2002. This is patterned to cover only the signal conductor area under the bridges.
the output pad at the driver and input pad at the receiver, due to the capacitive loads, which cause some mismatch in the termination of the interconnect. From the figure, the ‘one’ and ‘zero’ levels can be estimated to be approximately ±180 mV. The performance of this driver and interconnect is shown in table 4.1, where the bit error rate, signal-to-noise ratio, and eye opening factors have been compiled. The bit error rate was computed using equation 4.3, the signal-to-noise ratio was computed using 4.4, and the eye opening factor was computed using equation 4.5. During the operation of this circuit, the measured power was 13.57 mW; this value is also re- ported in table 4.3. The full schematic and transistor sizing for this driver is provided in appendix A.
Abstract—A shielded, conductor-backed coplanarwaveguide tech- nique is used to determine the complex permittivity and loss tangent of nano magnetic composite materials over X-band. The test composite material is synthesized by reinforcing cobalt ferrite particles with av- erage crystallite diameter 7.36 nm in low density polyethylene matrix with 2% and 4% volume fractions. The complex permittivity for low density polyethylene matrix and the composite samples, evaluated from the present technique at 9.887 GHz, are verified with cavity perturba- tion technique resonating at the same frequency. A new mathematical approach, using element-to-element correspondence of the ABCD ma- trix, is applied to calculate the complex propagation constant. The for- mulation facilitates evaluation of complex propagation constant over the test frequency range using scalar scattering parameters without altering the coplanarwaveguide geometry. The mathematical formu- lation is verified by performing permittivity measurements for air over the X-band.
9. Tsutsumi, M. and T. Ueda, “Left handed transmission characteristics of ferrite microstrip lines without series capacitive load,” IEICE Trans. Electron., Vol. E89, No. 9, 1318–1323, 2006. 10. Abdalla, M. and Z. Hu, “On the study of nonreciprocal left handed coplanarwaveguide over ferrite substrate with only shunt inductive load,” IEEE Microwave and Optical Technology Lett., Vol. 49, No. 11, 2810–2814, 2007.
thickness = 0.787 mm and tan δ = 0.0009. The thickness of copper is 35 µm. The CPW has a center conductor of width 1.8 mm and ground traces of width 4 mm. The gap between them is 0.1 mm. The main component of this ﬁlter is the set of spiral slots on the ground traces of the CPW. It has recently been reported that such spiral shaped slots on the ground traces of a CPW can introduce an inductance in the series path at frequencies well below its self-resonant frequency and can lead to interesting characteristics near its self-resonant frequency . Therefore these spiral slots provide an extra degree of freedom in microwave circuit design .
An ever-growing demand for high data rate in the current wireless applications, has led researchers to pay attention towards designing broadband and ultra-wideband antennas that can support a higher data rate (that has to be transmitted or received). Additionally, almost all wireless handheld devices demand the antennas to be compact, small sized and conformable to matching and un-matching surfaces. Microstrip patch antennas satisfy these properties and are therefore a preferred choice as they are easy integratable with RF circuits [1, 2]. A major drawback with conventional MPA of low bandwidth has been overcome by researchers through the use of techniques like using thick substrates , fractal geometries , stacking , Defected ground structures (DGS) [5, 16], circular shaped patches , slots in MPA , using coplanarwaveguide feeding (CPW)  and use of EBG
radiating elements, antennas, in a specific electrical and geometrical configuration. This occurs because of the vector addition of the total fields radiated by each element. Designing a very directive pattern requires the fields of the elements to interfere constructively in the desired directions and interfere destructively in the remaining space.
The current antenna iterations are presented in Fig. 1. And the geometry is given in Fig. 2. The designed antenna consists of paired elliptical curved radiating elements with slots at the upper portion. A coplanarwaveguide feed is used in the structure for simplicity and SRR shaped slots are placed in the ground plane for improving the impedance bandwidth. The split ring resonator slots are in two sizes as shown in the antenna geometry figure. The final dimensions of antenna is 44 X 40 X 1.6 mm on FR4 material with permittivity 4.4. The
Abstract—A novel coplanarwaveguide (CPW) fed wide tapered slot antenna (WTSA) is presented in this paper. A wideband CPW-to- wide slotline (WSL) transition is employed to feed the antenna. The corrugated edge structure and broken line tapered profile are also applied in this design to achieve wideband performance, as well as maintain compact size. A prototype of the antenna is fabricated. The measured results indicate that the antenna is a good candidate for UWB detection and imaging applications.
(Fig. 13(b)) of the proposed CPW-BPF. Note that S 1 is a quarter- wavelength at 17.8 GHz, and S 2 and S 3 are a quarter-wavelength at 6.85 GHz. The equivalent-circuit results are obtained from the circuit solver ADS. In Fig. 13(b), the lumped shunt capacitor in between the CPW-BPS and the CPW bandstop structure is mainly attributed to an increase of capacitive coupling from the small extrusion (w 5 ) of the
necessary time period of τ = 1.7 ms amounts to the transmission of about κτ = 42 photons. As we can see from these numbers, there is, in principle, no fundamental reason which would inhibit reaching the 100% detection eﬃciency for single photons enclosed in a high- Q cavity in this scheme. However, the detection scheme with the detection time around 1 ms is relatively ’slow’ compared to the recently reported fast detection schemes in circuit QED systems [4–7], where the time scale is in the range of μs.
The principle of Coplanar Waveguides (CPWs) is that the location of ground planes is on the same substrate surface as the signal line. This simplifies the fabrication process by eliminating via holes. CPWs are often used in designing power dividers, balanced mixers, coupler and filters. The microshield lines, become a solution to technological problem in the design of coplanar line due to many advantages such as the ability to operate without the need for use of air bridges for ground equalization, reduced radiation loss and reduced electromagnetic
Substrate integrated waveguide (SIW) , a low profile type of waveguide realized on substrate, has become more and more popular in recent years. The SIW circuits features merits of low-loss, low radiation, small size, and easy fabrications. In many cases, SIW can completely replace the rectangular waveguide for any circuit functions. Thus, we can anticipate that the hybrid design of planar structures such as microstrip lines, CPW lines, SIW with the conventional waveguides in microwave/millimeter-wave circuits/systems could be unavoidable. Therefore, transitions between various types of transmission lines are necessary. So far, transitions between different types of transmission lines have well been studied. In high frequency applications, microstrip devices are not efficient, and because wavelength at high frequencies are small, microstrip device manufacturing requires very tight tolerances. At high frequencies waveguide devices are preferred; however their manufacturing process is difficult. SIW is a transition between microstrip and dielectric-filled waveguide (DFW). Dielectric filled waveguide is converted to substrate integrated waveguide (SIW) by the help of vias for the side walls of the waveguide.
A planar microstrip circuit often needs to be cut into a specific shape, which is hard to realize in the millimeter-wave range. Furthermore, rectangular- waveguide components are voluminous and expensive to manufacture, which inevitably make the planar/nonplanar integration bulky and costly . A straightforward solution is to integrate the rectangular waveguide into the microstrip substrate. This will surely reduce the Q factor of the waveguide because of dielectric filling and volume reduction, but the entire circuit including planar circuit, transition and waveguide can be constructed using standard PCB or other planar processing techniques . This planar circuit is very useful for low-cost mass production and high Q value.