WIDE-RANGE VARIABLE-BANDWIDTH MICROSTRIP PATCH ANTENNA USING ELECTROMAGNETIC COUPLING

The rectangular microstrip patch antenna (RMPA) and square microstrip patch antenna (SMPA), designed to resonate at about 10 GHz, are excite d by a electromagnetically coupled microstrip line. The effect of vari ation in the offset and inset of the feed line on resonating frequency (f(r)), VSWR, and impedance bandwidth (BW) are experimentally studied using alumina substrate. It is seen that SMPA gives the highest BW of 4.98% for diagonal feed. The lowest BW obtained is for side-fed SMPA (0.012%), with maximum variation in BW of 1:278. The best trade-off to get such a variable BW easily, with only feed point adjustment using electromagnetic coupling for these patches, is to use a long-side-fed RMPA which gives sufficiently good BW variation of 1:98 and the lowest possible mismatch error, while adjusting the relative position of the feeder microstrip line. All the bandwidths mentioned above are only o btained when, simultaneously, VSWR < 2. Such an RMPA may also give mul tifrequency operation. (C) 1993 John Wiley & Sons, Inc.