Method for calculating the loss asymmetric vibrators with a remote power point

Existing software tools such as Altair FEKO, Ansys HFSS do not allow correct optimization of asymmetrical vibrators, the design of which includes grounding and counterweights. Meanwhile, counterweights often have large dimensions and high cost, comparable to the cost of antenna radiating elements. These circumstances make the development of a method for calculating the input impedance of an asymmetrical vibrator with a partially recessed base urgent. The proposed method for calculating the input resistance was built in the electrostatic approximation, which made it possible to exclude the radiation resistance from the calculation, leaving only heat losses in the underlying surface. The combination of the mirror image method and the average potential method allows one to take into account the influence of the interface between the media. The calculations performed using the developed technique allow making recommendations for determining the grounding depth and the need to install counterweights, depending on the type of soil and the electric length of the vibrator

Circular Shape Coplanar Waveguide Antenna Sensors for Cancer Detection Application

A compact microwave breast imaging (MBI) Omni-directional antenna applications has been proposed. As a primary health observation, the built antenna is inexpensive and has no health risk. Two antenna designs have been used together with the viable signal processing technology to identify the tumor available in breast phantom. At the 3.3 GHz frequency band, the electric length of the antenna is 0.22 λ × 0.176 λ × 0.0088 λ antenna has been offering the bandwidth is 40.6%.

Numerical study and experimental validation of a four-way feeding network with 45 deg broadband phase shifts for antenna array applications

A four-way network with 45 deg output phase shifts for feeding antenna array is studied in this work. To widen the phase imbalance, quarter wavelength short stubs with suitable characteristic impedances are introduced and numerically analyzed. Meanwhile, the wideband magnitude imbalance is also discussed by extending the inter-stage transmission line with proper electric length. The study is further confirmed by developing a prototype feeding network centered at 3 GHz. Results from the fabricated prototype network exhibit wideband good performance, both from numerical evaluations and experimental demonstrations.

Compact Diplexer with High Isolation and Wide Stopband Based on SIRs

A compact microstrip diplexer with a high isolation and improved out-of-band performance is proposed in this paper. The proposed diplexer is based on cascaded-quadruplet (CQ) bandpass filters (BPFs), which is composed of λ/4 stepped-impedance resonators (SIRs). By employing the edge and quasi-lumped coupling topology, a compact diplexer with improved passband selectivity can be achieved. Meanwhile, by appropriately adjusting the impedance and electric length ratios of SIRs, the stopband can be extended to 20 GHz with a rejection level of 10 dB, which is 12.7 times of the fundamental frequency. The predicted results on S parameters are compared with the measured ones and good agreement is achieved.

Design of Single- and Dual-Band Power Dividers Integrated Filtering Responses Based on SIRs

In this paper, two single- and dual-band equal power dividers (PDs) integrated filtering responses are proposed using quarter-wavelength stepped-impedance resonators (SIRs). By appropriately adjusting the impedances and electric length ratios of SIRs, the proposed structures can achieve compact sizes and wide stop-band performances. In addition, source-load coupling is applied to create a pair of transmission zeros at each side of the pass-bands, which can improve effectively the frequency selectivity and the out-of-band rejection. To validate the design theory, two single- and dual-band PDs with good filtering responses are designed, implemented and measured, respectively. The predicted results on S parameters are compared with the measured ones and good agreement is achieved.

Dispersion analysis of the solid helical pulse-forming line

In this paper, a solid helical pulse-forming line (HPFL) is described. The electromagnetic (EM) dispersion theory is used to calculate the important parameters of the HPFL based on tape helix model. Dispersion effects on the important EM parameters of HPFL, such as electric length and characteristic impedances, are analyzed. When Al2O3 ceramic is applied to be the dielectric in the HPFL, the pulse width of the HPFL is calculated nearly 50 ns only with the length of 305 mm. EM field simulation can draw the dispersion curve of the HPFL directly, which can describe the dispersion effect on the electric length of HPFL. Furthermore, the EM field simulation and experiments are carried out to verify the theoretical calculations of the pulse wide and characteristic impedances. Both simulation and experimental results can prove the EM analyses and calculations in this paper.

Effects of dielectric discontinuity on the dispersion characteristics of the tape helix slow-wave structure with two metal shields

In the tape helix slow-wave system, discontinuous dielectrics have great effects on the dispersion characteristics. In this paper, the tape helix slow-wave system, including an inner and an outer metal shield, tape helix, nylon support, and de-ionized water as filling dielectric, was analyzed. Effects of dielectric discontinuity caused by the support dielectric and filling dielectric on the dispersion characteristics were studied in detail. The dispersion relations, phase velocities, slow-wave coefficients, and electric lengths of the spatial harmonics in the system were calculated. Results showed that, if the permittivity of support dielectric was smaller than that of the filling dielectric, frequencies of the spatial harmonics in the system rose, phase velocities and slow-wave coefficients increased, the slow-wave effect of the system was weakened so that the previous electric length was shortened. The reverse condition corresponded to the reverse results, and the electromagnetic simulation also proved it. By use of the helical pulse forming line of accelerator based on the studied tape helix slow-wave system, the electric lengths of the system were tested as 188.5 ns and 200 ns in experiments where the thicknesses of nylon support were 6 mm and 3 mm, respectively. The theoretical calculation results 198 ns and 211 ns basically corresponded to experimental results, which only had relative errors as 5 and 5.5%, respectively.

Effects of dielectric discontinuity on the dispersion characteristics of the tape helix slow-wave structure with two metal shields

In the tape helix slow-wave system, discontinuous dielectrics have great effects on the dispersion characteristics. In this paper, the tape helix slow-wave system, including an inner and an outer metal shield, tape helix, nylon support and de-ionized water as filling dielectric, was analyzed. Effects of dielectric discontinuity caused by the support dielectric and filling dielectric on the dispersion characteristics were studied in detail. The dispersion relations, phase velocities, slow-wave coefficients and electric lengths of the spatial harmonics in the system were calculated. Results showed that, if the permittivity of support dielectric was smaller than that of the filling dielectric, frequencies of the spatial harmonics in the system rose, phase velocities and slow-wave coefficients increased, the slow-wave effect of the system was weakened so that the previous electric length was shortened. The reverse condition corresponded to the reverse results, and the electromagnetic simulation also proved it. By use of the helical pulse forming line of accelerator based on the studied tape helix slow-wave system, the electric lengths of the system were tested as 188.5 ns and 200 ns in experiment when the thicknesses of nylon support were 6 mm and 3 mm, respectively. The theoretical calculation results 198 ns and 211 ns basically corresponded to experimental results, which only had relative errors as 5 and 5.5%, respectively.