A novel millimeter-wave series-fed microstrip line antenna array

A novel millimeter wave series-fed microstrip line antenna array is designed. The antenna array consists of stepped inverted-cone stub sections placed on both edges of the microstrip line at a guided wavelength spacing. The 5 strip stub sections can alter the surface current cancellation at each guided wavelength in an ideal microstrip line. By properly tuning the length and height difference of the strip stubs, the equivalent surface currents can be focused to the stubbed inverted-cone sections present on the microstrip line edges and results in an effective radiation. The fabricated antenna array has return loss better than 10 dB around 27.3 GHz. Peak realized gain of 10.1 dBi is achieved and measured side lobe levels are better than -15 dB. The proposed antenna array has a very good radiation pattern and low side lobe levels which makes it a suitable direction for future integrated millimeter wave antenna arrays.