In this article, a novel microstrip antenna offering four operation bands to WiMAX (3.3–3.7 GHz), INST (4.5–4.8 GHz), downlink of X-band satellite communication (7.25–7.75 GHz) and X-band (8–12 GHz) is studied. The ring string-shaped radiator in the antenna consists of a circular ring patch and three elliptical rings of different sizes contributing to quad-band characteristics. The proposed antenna is fabricated on a FR-4 substrate with volume of 16 × 24 × 0.8 mm3. The measured reflection coefficient is lower than −20 dB and the peak gai...
