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Cost-effective antenna designs can be fabricated on low-cost materials, such as a durable reinforced fiberglass polymer resin material substrate. By recruiting such tools as OriginPro 8.5 software from OriginLab and the three-dimensional (3D), electromagnetic (EM) high-frequency structure simulator (HFSS) from Ansoft Corp., a compact microstrip-line-fed, H-shaped printed-circuit-board (PCB) patch antenna was designed and fabricated for multiband applications.

The antenna offers outstanding measured impedance bandwidth (with VSWR of less than 2.0:1) covering 3.25 GHz, from 9.75 to 13.0 GHz, with 8.5-dBi peak gain. The prototype antenna offers 0.63 dBi gain with 96% efficiency at 10.3 GHz, and 6.03 dBi gain with 84.2% efficiency at 12.5 GHz. The almost-steady radiation pattern makes the proposed antenna design suitable for X- through Ku-band applications.

The growing use of wireless technology is spurring the need for practical antenna designs.1,2 The demand for low-profile compact antennas with multiband compatibility has encouraged the development of various types of patch antennas, monopole antennas, and planar inverted-F antennas (PIFAs). Planar patch antennas, for example, are desirable for their low profiles, light weight, and simple structures.

Various dual-band antennas have been developed to save space, including circle slot antennas,3 stacked patch antennas,4 metamaterial branch line coupled antennas,5 dual-band dipole antennas,6 and slotted patch antennas on ceramic substrate material.7 Unfortunately, most of these antennas are either relatively large or lack the bandwidth for multiband use.

Low-Cost Substrate Supports Multiband Patch Antenna, Fig. 1

A considerable amount of research has been directed toward developing compact, low-cost, lightweight, planar microstrip patch antennas for multiple applications, so as to integrate with multipurpose communication modules. Antenna researchers have explored the development of compact, low-profile multiband planar antennas to meet the ever-increasing demands of smart multiple-technology wireless equipment.8

As an example, a dual-band, dual-linearly-polarized proximity-coupled patch antenna was designed with dimensions of 12.45 × 16 mm2.9 In addition, a 10 × 16 mm2 dual-band-notched square monopole antenna was proposed for ultrawideband (UWB) applications10 and a diamond dual-band antenna was designed for radio-frequency-identification (RFID) applications11; the RFID antenna features overall dimensions of 190 × 190 mm.2 Yet all of these antennas were relatively large in size, or else their performance levels were limited in gain and bandwidth.

To provide broad bandwidth in smaller antenna size, a 5-mm-long, microstrip-line-fed, inverted-H-shape, slotted patch antenna is proposed for dual-band use. Its compact size of 12 × 15 mm2 is significantly smaller than that of the other reported broadband antennas. Measurements of this proposed antenna design reveal an impedance bandwidth (with VSWR of under 2.0:1) ranging from 9.75 to 13.00 GHz (3.25 GHz), with peak gain of 8.5 dBi. The gain ranges from 0.63 dBi with 96% efficiency at the lower band at 10.3 GHz, to 6.03 dBi with 84.2% efficiency at the upper band at 12.5 GHz.

Low-Cost Substrate Supports Multiband Patch Antenna, Table

The antenna has been designed and analyzed with the aid of the three-dimensional (3D), finite-element-method (FEM) High Frequency Structure Simulator (HFSS) electromagnetic (EM) simulation software from ANSYS Corp.12 Figure 1 shows the design layout for the slotted radiating patch of the proposed antenna, with the optimized parameters for the proposed antenna listed in the table.

The inverted-H-shaped radiating patch antenna was obtained by cutting slots from the conventional rectangular shape. By cutting slots, the radiating patch takes a longer path around the slots for flowing current to reach the opposite edge. The desired resonant frequency and bandwidth are achieved by introducing slots on the radiating patch.

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