A Narrow-strip Broadband Microstrip Patch Antenna Based on Conducting Block Transition Fed

In this paper, a narrow-strip broadband microstrip antenna based on conducting block transition is designed. In order to meet narrow-strip dimensions (width is less than 0.22λ), a feed structure combining conducting block and short probe is applied, which plays a role of transition tuning. The formulas of transmission line mode and
$Q$
factor are analyzed to guide antenna design. An impedance bandwidth of 90% (-10dB) and 56% (-16dB) at operating frequency 3.5GHz is obtained. A parametric study of the antenna is described, including the thickness of the air layer, relative position of the feed source and the dimensions of the radiating patch. The antenna without the radiating patch is constructed and studied. By analyzing the current distribution on the patch surface, a anti-symmetric cross-feed structure in the longitudinal direction of the antenna is presented, which effectively improves the cross-polarization in H-plane.