In this paper, we present a new dual band planar antenna. The proposed antenna consists of a microstrip patch with a U-shaped slot that is fed by a broadband electromagnetic coupling probe, known as L-probe. Radiation characteristics of the antenna and different methods for control of the resonant frequencies are investigated.
Microstrip antennas are widely used in many applications due to their low profile, low cost and ease of fabrication. In some applications it is desired to have a dual band or multiband characteristics. These characteristics can be obtained by coupling multiple radiating elements or by using tuning devices such as varactor diodes.
However, these methods make antenna more complicated. A simple method to achieve the dual band characteristic in a microstrip antenna is embedding a slot in the patch as the structure proposed in which the radiating patch includes a pair of step-slots.
In microstrip antennas, embedded slots can also be used to enhance the impedance bandwidth of a single band antenna. A circular arc slot and a U-shaped slot have been investigated in order to broaden the bandwidth of a single band antenna.
To realize a broadband characteristic in feeding a microstrip antenna, an L-probe can be used. This feeding structure is also known as broadband electromagnetic coupling probe. In this paper, dual band characteristics are achieved by embedding a U-shaped slot in a rectangular patch.
Also, an L-probe is used to realize matching between the feed system and radiating system in a wide frequency range. Radiation performance of the designed antenna is simulated using the HFSS software and the simulated results are validated by experimental results.
Author: J. Ghalibafany | A. R. Attari | F. H. Kashani