Characteristic-mode assisted design of Lishu Huai-shaped patch antenna with penta-band unidirectional radiation

• Innovative Huai-shaped patch antenna operates across five frequency bands. • Utilizes Characteristic Mode Theory for high-directional radiation. • Compact design with average peak gain of 8 dBi, closely matching simulations. • Fusion of cultural artistry and advanced wireless communication technology. A directive, penta-band “Huai”-shaped patch antenna is proposed in this paper. The Lishu glyph, etched on the top face of a 0.5 mm RO4003C substrate, intrinsically supports seven characteristic modes but merged as five impedance bandwidths centered at 1.6, 1.9, 2.3, 2.7 and 3.2 GHz. A non-contact L-probe excites these modes while a 24 × 10 mm parasitic rectangle printed on the underside provides independent reactive tuning. The antenna achieves measured broadside gains averaging 8 dBi, front-to-back ratio >15 dB and a 2:1 frequency ratio within a compact 0.79 × 0.79 × 0.08 λ L 3 , where λ L is the free-space wavelength at the lowest resonant frequency. The 1.9 GHz band fully covers GSM-1800, the 2.3 GHz band covers LTE-2.3, the 2.7 GHz band reaches the upper edge of LTE-2.6, and the 3.2 GHz band services WiMAX, private 4G/5G and S-band back-haul links. By resizing the buried parasitic patch, individual modes can be fine adjusted with others, demonstrating a geometry-controlled tuning capability that merges cultural outline with multiband directive performance.