Conducting Side Sheet Loading to Enhance the Bidirectional Gain of a Wide Rectangular Slot Antenna in the 6–8.5 GHz Band

Abstract

Bidirectional gain of a wide rectangular slot antenna resonating over the 6 − 8.5 GHz band is enhanced by loading a pair of conducting sheets on the ground plane edges. These sheets are vertically loaded with respect to the slot antenna for meeting two purposes – (i) to appropriately converge the oblique radiation of the slot towards the broadside direction for enhanced gain and (ii) to retain the original impedance band (reflection coefficient ≤ −10 dB) of the slot by avoiding the formation of a resonant cavity (as in the case of superstrate loaded antennas). Optimized antenna using FR-4 substrate of side 50 mm has an overall size of 2.2λ₀ × 1.2λ₀ × 0.5λ₀, where λ₀ is the free-space wavelength at the mid-band frequency of the operating band. Measurements of fabricated antenna prototype demonstrate an impedance band of 5.97–8.53 GHz with bidirectional radiation pattern, with peak in-band gain of 5.52 dBi. The average gain improvement in the band is 3.99 dB, relative to the wide-slot antenna without sheet loading. The main attraction of the proposed method is its non-resonant nature, which enables almost uniform gain enhancement throughout the original impedance band, with bidirectional radiation pattern.

KEYWORDS:

• Conducting side sheets
• Gain enhancement
• Microstrip slot antenna
• Non-resonant method
• Offset feed
• Wideband

ACKNOWLEDGEMENTS

This work is financially supported by DST-FIST [Grant Ref: SR/FST/ETI-346/2013]. The first author thanks the UGC (University Grants Commission), India, for grant of fellowship scheme under the NET-JRF/SRF. Technical assistance of Mr. Mahesh Saini, EEE Department, BITS Pilani, is also acknowledged.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Ritish Kumar

Ritish Kumar received his BTech degree in electronics and communication engineering from UPTU, Lucknow, India, and ME degree in electronics engineering from Devi Ahilya Vishwavidyalaya (DAVV), Indore, India. He is currently working towards the PhD degree at Birla Institute of Technology and Science, Pilani (BITS Pilani), Rajasthan, India. His research interests are microstrip antennas, ultra-wideband antennas, time-domain analysis, and non-destructive microwave testing. E-mail: [email protected]

A. V. Praveen Kumar

A V Praveen Kumar received PhD degree in microwave electronics from the Department of Electronics, Cochin University of Science and Technology (CUSAT), Kerala, India, in 2009. From 2008 to 2013, he was a post-doctoral fellow in the Engineering Department, Lancaster University, UK, where he was involved in the design of radio-frequency cavities for particle accelerators. Presently, he is an associate professor in the Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science, Pilani (BITS Pilani), Rajasthan, India. His research interests are from the field of radiofrequency and microwave engineering, on antennas, cavity resonators, and material characterization.