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radiation patterns of the proposed antenna in the two orthogonal planes at the two design frequencies of 0.9 and 1.8 GHz. The measured antenna gains are 2.65 and 4.1 dBi at the lower and upper resonant frequencies, respectively. As shown in the XZplane patterns, the proposed monopole with the ground shorted inset sleeve has omni-directional radiation patterns at both design frequencies. Figure 4 shows the measured return losses of the proposed monopole antenna with resonant frequency tunability. It can be seen that the PISMA has dual resonant modes with increasing inset sleeve length. In the case of all diodes off, the measured 10 dB impedance bandwidth at the lower resonant mode is 30 MHz (0.63-0.66 GHz), which is about 4.65% with respect to the center frequency of 0.645 GHz. At the upper band, the impedance bandwidth is 480 MHz (1.43-1.91 GHz), which is about 28.7% centered at 1.67 GHz. The measured radiation patterns in the two orthogonal planes at both design frequencies of 0.65 and 1.75 GHz are plotted in Figures 5(a) and 5(b), respectively. From Figure 5, it can be seen that the omnidirectional radiation patterns in the XZ-plane are similar to those of the conventional monopole and the model shown in Figure 1(a). The measured peak gains at the lower and upper frequencies are 2.1 and 1.8 dBi, respectively. CONCLUSIONSThe CPW-fed PISMA with dual-band tunability is proposed in the letter. It uses the ground shorted inset sleeve of which the length is controlled by the PIN diode. Because the ground shorted inset sleeve leads to both the resonant mode by the virtual feed and the additional resonant mode in the upper band, dual-band operation can be easily achieved without any additional metal strips. Also, the proposed monopole antenna can produce the omni-directional radiation pattern at the two design frequencies.ABSTRACT: This article presents a new reflection-type 360 phase shifter, for Ku-and Ka-bands applications. At 12 GHz, the measured prototype has more than 360 phase shift with insertion loss of 3.3 6 0.5 dB. For the Ka-band circuit, the lowest insertion loss is obtained at 30.3 GHz (3.6 dB 6 1.8 dB) and the phase shift is 315 .ABSTRACT: This article presents the design of a novel unequal Wilkinson power divider for dual-band operation. The proposed power divider can operate at arbitrary two frequencies without reactive components. The design parameters of the dual-band power divider are presented in explicit closed form. The validity of this analysis is confirmed through the design, simulation, and experimental results with a power divider for 1 and 2.5 GHz. The experimental results show that the designed unequal power divider fulfills all the features of a conventional Wilkinson power divider.