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This paper focuses on a printed inverted-F antenna (PIFA) with meandering line and meandering shorting strip under 2.4 GHz industrial, scientific, and medical (ISM) band for Internet of things (IoT) applications. Bluetooth Low Energy (BLE) technology is one of potential platforms and technologies for IoT applications under ISM band. Printed circuit board (PCB) antenna commonly used in commercial and medical applications because of its small size, low profile, and low cost compared to low temperature cofired ceramic (LTCC) technology. The proposed structure of PIFA is implemented on PCB to gain all these advantages. Replacing conventional PCB line in PIFA by the meandering line and meandering shorting strip improves the efficiency of the PIFA as well as the bandwidth. As a case study, design and measurement results of the proposed PIFA are presented.

version used. The simulated antenna pattern in both planes is shown in Figure 5. The half-power beamwidth in the H-plane is 120 at 3.7 GHz and is changing very little with frequency inside the band (not more than 2 ). Figure 6 shows the measured antenna pattern. To obtain 120 beamwidth, the reflector distance had to be adjusted during experimentation in the anechoic chamber; its final distance from the ground plane is 25.5 mm. Both the simulated and the measured beamwidths in the E-plane were 12.5 , and the side-lobe level was below À10 dB. Note that the measured VSWR given in Figure 3 as well as the radiation pattern shown in Figure 6 were obtained with the final antenna, i.e., with the reflector position adjusted in the anechoic chamber experimentation.ABSTRACT: In this letter, a compact tunable lumped-element Wilkinson power divider is proposed. It is realized by the electronically tunable microwave impedance transformers controllable by varactor diodes. The proposed divider possesses a tunable frequency range over a bandwidth of 53% different from the conventional Wilkinson power divider. Experimental results show that it can operate over the tunable frequency range from 1.1 to 1.9 GHz with more than 50 dB isolation between the isolated ports.

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