8) VSWR properties and chip inductors

This section shows how VSWR properties are related to 3 chip inductors.
The chip inductors L1 and L2 are mounted in series with the feed point and one of the terminals of the chip antenna and used to adjust the resonance frequency. The chip inductor L3 inserted in parallel between the feed point and GND is for impedance tuning. The sample board used here has the same dimensions as the standard antenna sample explained in section 1.

・Fig.8-1 shows the change of VSWR properties when L3 is varied and L1 and L2 are fixed. While minimum peak frequency hardly changes, VSWR value becomes larger than 1 when replacing L3 from the optimal value 27nH as shown in Fig.8-2.
・Fig.8-3 indicates that a change of L2 can make resonance frequency shift higher or lower without making the minimum VSWR value larger. Fig.8-4 shows resonance frequency dependence on the value of L1+L2. This result tells us that resonance frequency shifts 0.76MHz to the lower side as L3 increases by 1nH.










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