Dual-Fed Microstrip Patch with Higher-Order Radiating Mode Achieving Port-to-Port Isolation

This paper presents design guide and applications of a newly proposed dual-fed patch antenna. Four shunt stubs and slots form slow-wave edges and reduce the length of radiating edge by 40 %. The slow-wave edge and non-central feedings excite the first higher-order mode for radiation. The proposed design provides broadside radiation pattern with antenna gain of 7 dBi. The signal injected to one port can be radiated by the half patch and no signal is leaked to another port. Port-to-port isolation is achieved and it is proposed in the dual-fed linearly polarized antenna. The dual-fed structure is convenient for the direct integration to the balanced circuits without use of power divider/combiner or balun. The proposed design is useful to compact balanced active integrated antenna designs. The disadvantage of power divider such as electrically large size and lumped element requirement can be eliminated. Most importantly, the devices working with the proposed antenna operate independently to avoid unwanted feedback and oscillation.