Compact dual-frequency circular microstrip antenna with an offset circular slot

✍ Scribed by Jui-Han Lu; Kin-Lu Wong

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 129 KB
• Volume: 22
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/(sici)1098-2760(19990820)22:4<254::aid-mop11>3.0.co;2-s

✦ Synopsis

This paper presents a new, compact, dual-frequency design of single-feed circular microstrip antennas with an offset circular slot placed close to the patch boundary. It is found that, when the radius of the offset slot is about 0.38᎐0.62 times the radius of the circular patch, dual-frequency operation can be achie¨ed using a single probe feed. The two operating frequencies ha¨e orthogonal polarization planes, and ha¨e a low frequency ratio of about 1.15᎐1.18. The two frequencies can also be much lower than the fundamental resonant frequency of a corresponding simple circular patch antenna without the offset slot. This beha¨ior makes the proposed antenna ha¨e a reduced antenna size as compared to a simple circular patch antenna operated at either one of the two frequencies. Details of the antenna design and experimental results are presented.