UC-EBG on LTCC for 60-GHz Frequency Band Antenna Applications

The relatively high dielectric constant of the low-temperature cofired ceramic (LTCC) substrate materials can reduce the antenna gain and increase the mutual coupling in antenna arrays due to the increased surface-wave power. We present a design of a uniplanar-compact electromagnetic band-gap (UC-EBG) structure on the Ferro A6-S LTCC tape system operating in the 60-GHz frequency band. The UC-EBG design is used with an aperture-coupled microstrip-line-fed patch antenna (ACMPA) and with a 16-element array to increase the antenna gain. The UC-EBG is also used to reduce the mutual coupling between antennas in the E- and H-planes. The performance of the antennas with and without UC-EBG are evaluated with the probe-station and radiation-pattern measurements. In addition, the reflection from the UC-EBG surface is measured using a WR-15 waveguide excitation. Good agreement is achieved between the simulations and the measurements. An increase of up to 4.5 and 2.3 dBi is achieved in the gain for a single element and for a 16-element array, respectively. A reduction of up to 11.8 dB is observed in the E-plane coupling between two patches. The presented design is suitable for electromagnetic shielding, reduction of coupling in integrated LTCC modules, and providing high gain antennas for low-cost millimeter-wave applications.