PIER Letters | PIER Journals

2026-01-25 Latest Published

Methods for Evaluating PN Sequences in Spread Spectrum TDR
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By Phat Nguyen Mouad Addad Samuel Makin Joel B. Harley Cynthia Furse Paul K. Kuhn

Progress In Electromagnetics Research Letters, Vol. 129, 15-20, 2026

doi:10.2528/PIERL25102405 | Google Scholar

Abstract

This paper describes a Pseudo-Noise (PN) sequence evaluation tool that analyzes potentially corrupted PN sequences and assigns a metric score indicating the quality of the received sequence. The PN tester is designed to support Spread Spectrum Time Domain Reflectometry (SSTDR) by evaluating reflected PN sequences and determining whether the received signal is valid or too corrupted for use. Signal degradation is influenced by noise levels and channel filters encountered by the sequence. To simulate real-world conditions, various types of noise and filtering effects - representing capacitive or inductive coupling - were applied to a maximum-length PN sequence. The evaluation model demonstrated a consistent decline in correlation as signal distortion increased, confirming its effectiveness in assessing signal quality.

2026-01-25

PIER Letters

Vol. 129, 15-20, 2026

doi:10.2528/PIERL25102405

download: 26

Methods for Evaluating PN Sequences in Spread Spectrum TDR

Phat Nguyen, Mouad Addad, Samuel Makin, Joel B. Harley, Cynthia Furse and Paul K. Kuhn

2026-01-25

PIER Letters

Vol. 129, 9-14, 2026

doi:10.2528/PIERL25110306

download: 46

Characterization of Complex Permittivity Using Microwave Diffraction of Spheres

Elio Samara, Jean-Michel Geffrin and Amelie Litman

The determination of the complex permittivity of materials is a fundamental aspect of experimental electromagnetics. This study introduces a method that estimates the complex permittivity by comparing the measured bistatic field diffracted by spherical samples in an anechoic chamber with fields computed using Mie theory. The approach is applied to a molded PMMA sphere and two 3D-printed materials (Clear Resin V4.1 and Rigid 10K) over the 2-18 GHz band. The retrieved permittivity values show excellent agreement with reference data for PMMA and enable reliable characterization of low-loss 3D-printed materials, with uncertainties quantified from both experimental and numerical contributions. These results confirm the effectiveness of microwave-diffraction-based characterization and highlight promising perspectives for future investigations on an even larger frequency band.

$Characterization of Complex Permittivity Using Microwave Diffraction of Spheres$

2025-12-18

PIER Letters

Vol. 129, 1-8, 2026

doi:10.2528/PIERL25102202

download: 330

Compact Gap-Coupled Circularly Polarized Broadband Metasurface Antenna Based on Characteristic Mode Analysis

Xuemei Zheng and Ao Gui

In response to the demand for broadband antennas in satellite communications, this paper sets out the proposal of a broadband circularly polarised metasurface antenna. Based on the theory of characteristic mode analysis of super surface, a pair of characteristic modes with the potential to realize circular polarization broadband are obtained and used as the modes to be excited. At the same time, the metasurface current is analyzed; the position of the floor gap is determined according to the results; and the shape of the floor gap is designed to better stimulate the characteristic mode. Subsequently, the power is transmitted through the microstrip line gap coupling feeding structure to excite the selected mode. Finally, an MTS antenna with dimensions of 0.9λ₀ × 0.9λ₀ × 0.076λ₀ at a centre frequency of 5 GHz was determined. The antenna was modeled using CST, a 3D electromagnetic simulation software, and then physically tested for verification. The experimental findings indicate that the impedance bandwidth of the antenna in question is 4.20-5.83 GHz (relative bandwidth of 32.6%). Furthermore, the 3 dB axial ratio bandwidth is 4.38-5.97 GHz (relative bandwidth of 30.7%).