Uncertainty of S-Parameter Measurements on PCBs due to Imperfections in the TRL Line Standard

This paper evaluates the uncertainty of S-parameter measurements on multilayer printed circuit boards (PCBs) due to the uncertainties of the dimensions and dielectric properties of the line standard in the Thru-Reflect-Line (TRL) calibration. This evaluation is performed in two ways: one is based on repeated TRL calibrations with a randomly perturbed line standard, and the other is based on equations given by Stumper. The two methods require the uncertainties of the S-parameters of the TRL line standard, which are obtained from the uncertainties of the dimensions and dielectric properties using three-dimensional electromagnetic Monte Carlo simulation. The two methods agree well with each other. This study also shows how to apply impedance renormalization in Stumper’s equations. We design the TRL standards and the devices under test (DUTs) in PCB stripline and precisely measure the cross-sectional dimensions of the fabricated striplines. Uncertainty analysis based on the measured values enables us to investigate the impact of realistic deviations in the dimensions of the TRL line standard on the S-parameter measurement uncertainty of the DUTs. Finally, as an example, we evaluated the uncertainty in the measured S-parameters of a Beatty line on the fabricated PCB.

Metamaterial inspired multi-split square shaped printed antenna for WLAN applications

This paper describes the design of a compact dual band microstrip antenna based on metamaterial inspired split ring radiating element and a complementary spilt ring resonator (CSRR). The antenna has a very compact dimension of 20×20×0.8 mm3. It covers the 2.5/5.2/5.8 GHz frequencies, pertaining to IEEE 802.11 b/g/a standards suitable for WLAN applications with a -10dB impedance bandwidth of 250 MHz and 860 MHz. The CSRR creates a negative permittivity region, thus providing miniaturization of the antenna and the introduction of additional split gaps in the radiating element creates a positive permeability within the desirable frequency range, yielding better impedance matching. The negative properties of those structures are verified using S-parameter retrieval method. A prototype of the proposed antenna is fabricated and the measured results are fairly in good agreement with the simulation results. Dipole like radiation patterns are observed at both the operating frequencies. The measured peak gains are 0.58 dBi, 1.27 dBi and 2.10 dBi at 2.5, 5.2 and 5.8 GHz respectively.

LHCP four patches stack triangular truncated antenna using corporate feed microstrip-line for CP-SAR sensor

<span>In this paper, we acquire the configuration of the left-hand circular polarization (LHCP) array four patches stack triangular truncated microstrip antenna. This construction use the basic corporate feed microstrip-line with modified lossless T-junction power divider on radiating patch for circularly polarized-synthetic aperture radar (CP-SAR) sensor embedded on unmanned aerial vehicle (UAV) with compact, small, and simple configuration. The design of circular polarization (CP) is realized by truncating the whole three tips and adjusting the parameters of antenna at the target frequency, <em>f </em>= 5.2 GHz. The results of characteristic performance and <em>S</em>-parameter for the LHCP array four patches stack antenna at the target frequency show successively about 9.74 dBic of gain, 2.89 dB of axial ratio (<em>Ar</em>), and </span><span>-</span><span>10.91 dB of S-parameter. Moreover, the impedance bandwidth and the 3 dB-<em>Ar</em> bandwidth of this antenna are around 410 MHz (7.89%) and 100 MHz (1.92%), respectively.</span>

Microstrip Impedance Management through Multilayer PCB Stack-Up: Discontinuity Compensation Voids with Asymmetric Dielectrics

To process high-frequency signals on a printed circuit board (PCB), it is often necessary to carefully analyze and select the pad widths of the chip packages and components to match their impedance to the standard Z0. Modern PCBs are complex multilayer designs, utilizing either only high-end laminates, low-end laminates, or a combination of both. The on-board component footprints usually have larger pads that become discontinuities and corrupt the impedance of critical traces. One way to address this issue is to include reference plane cutouts as a measure of compensation. This paper aims to find out how an asymmetric dielectric stack-up affects the microstrip discontinuity impedance compensation using reference plane cutouts. The selected board layer stack-up imitates several different practical design scenarios, including costly PCBs that strictly comprise high-end dielectric materials, as well as trying to lower PCB cost by introducing low-cost materials without major performance sacrifice. S-parameter measurements are performed and confirmed by time domain reflectometry (TDR) measurements.

Multi-modal Scattering and Propagation Through Several Close Periodic Grids

<div>The presented method describes reflection and transmission of electromagnetic waves at multiple closely stacked metal grids using multi-modal S-parameter propagation. For that, the surface admittance of every metal layer was determined, through a novel semi-analytic approach that uses simple Fourier transformations instead of solving an integral equation. The modal components of this surface admittance were used to express the generalized scattering matrices of the individual grids. By applying multi-modal propagation techniques to the resulting scattering parameters, it was possible to model the electromagnetic interactions within a multilayer stack of periodic impedance sheets. Resulting reflection and transmission parameters perfectly matched the corresponding full-wave simulations even above the grating lobe regime. In the end, the universality of the proposed method was proven on a layer stack, connected to lumped components.</div>

Multi-modal Scattering and Propagation Through Several Close Periodic Grids

<div>The presented method describes reflection and transmission of electromagnetic waves at multiple closely stacked metal grids using multi-modal S-parameter propagation. For that, the surface admittance of every metal layer was determined, through a novel semi-analytic approach that uses simple Fourier transformations instead of solving an integral equation. The modal components of this surface admittance were used to express the generalized scattering matrices of the individual grids. By applying multi-modal propagation techniques to the resulting scattering parameters, it was possible to model the electromagnetic interactions within a multilayer stack of periodic impedance sheets. Resulting reflection and transmission parameters perfectly matched the corresponding full-wave simulations even above the grating lobe regime. In the end, the universality of the proposed method was proven on a layer stack, connected to lumped components.</div>