Design Study of Normal Mode Helical Antenna with Dual-Frequency and Circular Polarization Used in Mobile. J. eng. sustain. dev. [انترنت]. 1 أغسطس، 2013 [وثق 18 مايو، 2024];17(3):79-93. موجود في: https://jeasd.uomustansiriyah.edu.iq/index.php/jeasd/article/view/999