D. S. Chandu and S. S. Karthikeyan, "Broadband circularly polarized printed monopole antenna with protruded L-shaped and inverted L-shaped strips", Microwave and Optical Technology Letters, Vol. 60, no. 1, pp. 242–248, 2018.
Rusan Kumar Barik, Rajender, R and S. S. Karthikeyan, "A Miniaturized Wideband Three-Section Branch-Line Hybrid With Harmonic Suppression Using Coupled Line and Open-Ended Stub ", IEEE Microwave and Wireless Components Letters, Vol. 27, no. 12, pp. 1059-1061, 2017.
Rusan Kumar Barik and S S Karthikeyan, "Design of dual/tri-frequency impedance transformer with ultra-high transforming ratio", Vol. 9, no. 10, pp. 1951-1960, 2017.
Idury Satya Krishna, Rusan Kumar Barik, SS Karthikeyan, "A dual-band crossover using cross-shaped microstrip line for small and large band ratios", International Journal of Microwave and Wireless Technologies, Vol. 9, no. 8, pp. 1629-1635, 2017.
R. K. Barik and S. S. Karthikeyan, "Dual-Frequency Impedance Transformer Using Coupled-Line For Ultra-High Transforming Ratio", Radio Engineering, Vol. 26, no. 4, pp. 1067-1074, 2017.
Rusan Kumar Barik and S. S. Karthikeyan, "A novel quad-band impedance transformer with ultra-high transforming ratio", International Journal of Electronics and Communication, Vol. 78, pp. 157–161. Aug. 2017.
Rusan Kumar Barik and S. S. Karthikeyan,"A novel design of ultra‐high impedance transforming ratio quad‐band matching network", Microwave and Optical Technology Letters, Vol. 59, no. 8, pp. 2021-2026, 2017.
K.V. Phanikumar and S. S. Karthikeyan, “Highly compact wideband double-section rat-race hybrid with harmonic suppression using series and shunt stepped impedance transmission lines”, International Journal of Microwave and Wireless Technologies, Vol. 9, no. 4, pp. 797-803, 2017.
Rusan Kumar Barik, K.V. Phanikumar and S. S. Karthikeyan, “Design of a Dual-Band Microstrip Branch-Line Balun Using T-Shaped Coupled Lines”, Microwave and Optical Technology Letters, Vol. 59, no. 5, pp. 1197-1202, 2017.
Idury Satya Krishna, Rusan Kumar Barik, S. S. Karthikeyan and Priyanka Kokil, “A Miniaturized Harmonic Suppressed 3 dB Branch Line Coupler Using H-shaped Microstrip Line”, Microwave and Optical Technology Letters, Vol. 59, no. 4, pp. 913-918, 2017.
Chandu D S and S S Karthikeyan, “A Novel Broadband Dual Circularly Polarized Microstrip-Fed Monopole Antenna”, IEEE Transactions on Antennas and Propagation, Vol. 65, no. 3, pp. 1410 - 1415, 2017.
K.V. Phanikumar and S. S. Karthikeyan, “Miniaturised quadrature hybrid coupler using modified T-shaped transmission line for wide-range harmonic suppression”, IET Microwaves, Antennas & Propagation Vol. 10, no. 14, pp. 1522-1527, 2016.
Rusan Kumar Barik, K.V. Phanikumar and S. S. Karthikeyan, “Design of a Quad-Band Branch Line Balun Using Extended Pi-Shaped Coupled Lines”, IEEE Microwave and Wireless Components Letters, Vol. 26, no. 10, pp. 771-773, 2016.
Rusan Kumar Barik, K.V. Phanikumar and S. S. Karthikeyan, “A compact wideband harmonic suppressed 10 dB branch line coupler using cascaded symmetric PI sections”, Microwave and Optical Technology Letters, Vol. 58, no. 7, pp. 1610-1613, 2016.
K.V. Phanikumar and S. S. Karthikeyan, “A novel two section branch line coupler employing different transmission line techniques”, International Journal of Electronics and Communication, Vol. 70, no. 5, pp. 738-734, 2016.
K. V. Phanikumar and S. S. Karthikeyan, “Wideband three section branch line coupler using triple open complementary split ring resonator and open stubs”, International Journal of Electronics and Communication, Vol. 69, no. 10, pp. 1412-1416, 2015.
K. V. Phanikumar and S. S. Karthikeyan, “A compact 1:4 lossless t-junction power divider using open complementary split ring resonator”, Radio Engineering, Vol. 24, no. 3, pp. 717-721, 2015.
S. S. Karthikeyan and Rakhesh Singh Kshetrimayum, “Compact and Wide Stop band Lowpass Filter Using Open Complementary Split Ring Resonator and Defected Ground Structure”, Radio Engineering, Vol. 24, no. 3, , pp. 708-711, 2015.
S. S. Karthikeyan and R. S. Kshetrimayum “Compact, harmonic suppressed power divider using open complementary split-ring resonator”, Microwave and Optical Technology Letters (MOTL), Vol. 53, pp. 2897-2899, 2011.
S. S. Karthikeyan and R. S. Kshetrimayum “Size miniaturized rat-race coupler using open complementary split ring resonator”, IEICE Transaction on Electronics, Vol. E94-C, pp. 1601-1604, 2011.
S. S. Karthikeyan and R. S. Kshetrimayum, “Compact, Deep and Wide Rejection Bandwidth Lowpass Filter using Open Complementary Split Ring Resonator, Microwave and Optical Technology Letters (MOTL), Vol. 53, pp. 845-848, 2011.
S. S. Karthikeyan and R. S. Kshetrimayum “Composite right/left handed transmission line based on open slot split ring resonator”, Microwave and Optical Technology Letters (MOTL), Vol. 52, pp. 1729-1731, 2010.
S. S. Karthikeyan and R. S. Kshetrimayum, Notched UWB bandpass filter using Complementary Single Split Ring Resonator”, IEICE Electronics Express (ELEX), Vol. 7, pp. 1290-1295, 2010.
S. S. Karthikeyan and R. S. Kshetrimayum, "Compact Wideband Bandpass Filter using Open Slot Split Ring Resonator and CMRC," Progress In Electromagnetics Research Letters (PIERL), Vol. 10, pp. 39-48, 2009.
S. S. Karthikeyan and R. S. Kshetrimayum, "Harmonic suppression of parallel coupled microstrip line bandpass filter using CSRR," Progress In Electromagnetics Research Letters (PIERL), Vol. 7, 193-201, 2009.
R. S. Kshetrimayum, S. S. Karthikeyan and D. Dey, “Bandgap determination of triangular lattice EBGs in the ground plane”, International Journal of Electronics and Communication, Vol. 63, no. 8, pp. 699-702, 2009.
R. S. Kshetrimayum, S. Kallapudi and S. S. Karthikeyan, “Stop Band Characteristics for Periodic Patterns of CSRRs in the Ground Plane and its Applications in Harmonic Suppression of Band Pass Filters”, International Journal of Microwave and Optical Technology, Vol. 3, no. 2, pp. 88-95, 2008.
R. S. Kshetrimayum, S. Kallapudi and S. S. Karthikeyan, “Stopband Characteristics for Periodic Patterns of CSRRs in the Ground Plane”, IETE Technical Review, Vol. 24, no 6, pp 449-460, 2007.