Design and Parametric Sensitivity Analysis of a Six-Disc Short-Backfire Disc-on-Rod Antenna for 2.4 GHz Applications

Ashikur Mollik, Md Emadur Rahman Ekra*, Md Nadim Hosain, Md Daud Ibrahim

Abstract

This study designs and analyzes a copper disc-on-rod endfire antenna for the 2.4 GHz industrial, scientific, and medical (ISM) band. Six coaxial copper discs of graded radius are mounted on a continuous copper rod of 2 mm radius, and a cylindrical copper cavity at the feed end serves as a surface-wave launcher, impedance-matching element, and rear shield. Although the structure resembles a Yagi-Uda array, this paper shows that it belongs to the disc-on-rod class of surface-wave radiators and analyzes it with slow-wave and travelling-wave theory. This paper models the complete geometry using the finite element method in Ansys HFSS and sweeps twelve-dimensional parameters individually. The final design resonates at 2.400 GHz with a simulated reflection coefficient of −39.08 dB and a −10 dB band extending from approximately 2.31 to 2.58 GHz. The far field shows a single forward lobe with rear radiation suppressed by more than 20 dB. Converting the simulated far-field data to absolute units gives a peak realized gain of 10.67 dBi, which lies within the envelope of analytical endfire estimates for the same electrical length and corresponds to 55% of the Harrington normal-gain bound. The normalized disc size and pitch of the uniform guiding section fall within the design window established empirically in the classical disc-on-rod literature. The sensitivity analysis shows that the launcher region governs both the resonant frequency and the quality of the match and requires sub-millimetre accuracy, whereas the guiding section tolerates errors of about 1 mm and the conductor thickness has no electromagnetic effect. All results are simulation-based; this study states the limitations and outlines a validation protocol.

Keywords

disc-on-rod antenna; surface-wave antenna; slow-wave structure; 2.4 GHz ISM band; finite element method

Cite This Article

Mollik, A., Ekra, M. E. R., Hosain, M. N., Ibrahim, M. D. (2026). Design and Parametric Sensitivity Analysis of a Six-Disc Short-Backfire Disc-on-Rod Antenna for 2.4 GHz Applications. International Journal of Scientific Advances (IJSCIA), Volume 7| Issue 5: Sep – Oct 2026, Pages 704-714. URL: https://www.ijscia.com/wp-content/uploads/2026/10/Volume7-Issue5-Sep-Oct-No.1091-704-714.pdf

Volume 7 | Issue 5: Sep – Oct 2026