In this letter, a novel inductive post half mode substrate integrated waveguide (HMSIW) bandpass filter is presented. The filter keeps the advantages of an SIW filter but with a reduction of nearly one-half in size. A very good agreement is observed between the simulation and the measurements.

noise. Figure 8 shows the measured phase noises of the freerunning, injection signal and injection-locked oscillator outputs in the divide-by-2 mode. The phase noise of free-running oscillator at 1 MHz offset is about Ϫ113 dBc/Hz. After external power injection at 0 dBm, the ILFD phase noise is about Ϫ134 dBc/Hz in the divide-by-2 mode. The phase noise of divide-by-2 ILFD is lower than that of the free-running oscillator by 21 dB. Table 1 shows the comparison between our presented injectionlocked divider and previously published reports. The FD has a comparable performance but with the smaller occupied chip area. CONCLUSIONA small die area 2.4-GHz FD employing the 3D helical inductors fabricated in the 0.18-m CMOS technology have been demonstrated, and the FD circuit uses the concept of inductor tapping to shift the parasitic drain-to-bulk junction capacitances of active switching MOSFET's away from paralleling with the varactors. The fixed capacitance that affects the tuning range is reduced; therefore, the locking range can be increased. Two 3D inductors have been used to reduce the chip occupied area and lower chip cost. The die area is 0.664 ϫ 0.731 mm 2 . The same concept of using single 3D inductor in FD can be used to reduce chip size of FD with an inductor. The implemented FD core consumes power of 2.6 mW at 1 V supply voltage, and the measured locked phase noise is Ϫ134 dBc/Hz at 1 MHz offset from the output oscillation frequency of 2.34 GHz. ACKNOWLEDGMENTThe authors thank the Staff of the CIC for the chip fabrication and technical supports. 2. M. Tiebout, A CMOS direct injection-locked oscillator topology as high-frequency low-power frequency divider, IEEE J Solid State ABSTRACT: A rectangular microstrip antenna is gradually divided into equal smaller elements along the width, and lengths of these smaller strips are varied to increase the separation between the resonances to obtain dual and triple frequency operation. Likewise, configurations consisting a maximum of five strips have been investigated. For configurations with two strips only dual frequency operation has been obtained, whereas for configurations with more than two strips both dual and triple frequency operation has been obtained. With increase in number of elements, the separation between different resonances is more and the radiation pattern is also similar in two frequency bands. Experiments have been performed and the results are in agreement with the simulations. Key words: gap coupled rectangular microstrip antenna; dual frequency rectangular microstrip antenna; triple frequency microstrip antennas; compact gap coupled microstrip antennasFigure 1 Gap coupled RMSA configurations obtained by splitting a single RMSA into smaller elements along the width; (a) single RMSA, Gap-coupled configuration with (b) two strips, (c) three strips, (d) four strips, and (e) five strips