Experimental investigation of impedance characteristics of patch antennas with finite-size substrates

Abstract

The investigation of the impedance characteristics of patch antennas on finite‐size dielectric substrates is conducted experimentally. A probe‐fed rectangular patch antenna with double L‐shaped slots is selected for the tests. Both measured VSWR and input impedance are employed to evaluate the effect of the finite‐size substrates with different thicknesses and permittivities on the impedance characteristics of patch antennas. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 107–111, 2000.

Impedance characteristics of probe‐fed L‐shaped plate antenna

“…0048-6604/01/2000RS002350511.00 [Prasad and King, 1961;Taga and Tsunekawa, 1987;Hall, 1987;Huynh and Lee, 1995;Luk et at., 1998;Chen, 2000]. By means of various matching techniques the impedance bandwidths of the suspended plate antennas have reached up to about 20-40% for 2:1 VSWR.…”

“…Antennas with low profile and broad bandwidth are always attractive to antenna researchers and engineers. For example, many solutions such as microstrip antennas, transmission line (typically inverted-L or-F) antennas, and suspended plate antennas have been proposed for broadband probe-fed single-element single-layer applications [Chang et al, 1986;Schaubert et al, 1998;Prasad and King, 1961;Taga and Tsunekawa, 1987;Hall, 1987;Huynh and Lee, 1995;Luk et al, 1998;Chen, 2000]. In particular, significant efforts have long been devoted to the enhancement of impedance bandwidth.…”

Broadband Probe-Fed Plate Antenna

“…Efforts to increase the impedance bandwidth of the transmission-line antennas in have yielded bandwidths up to about 10% for VSWR=2:1. To further alleviate the narrow bandwidth problem, some techniques, such as, cutting slots at a patch, using a threedimensional (3-D) transition, and electromagnetically coupling a suspended plate have been currently suggested, largely enhancing the impedance bandwidth up to the order of 20 40% for VSWR=2:1 [1][2][3][4][5][6][7]. In these solutions, air or foam of low permittivity is employed to support the radiators instead of the dielectric substrates usually used in the microstrip patch antennas.…”

“…In general, the radiator, namely, an electrically conducting plate is essentially suspended at a height of 0.08 operating wavelength and fed by a coaxial probe. To compensate the large input reactance stemming from the long probe, we may cut the slots acting as reactive loading at the plate [1][2][3][4][5]. However, the introduction of the slots unquestionably alters the distribution of the electric currents at the plate surface and seriously, excites modes of higher order.…”