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is 8.5 by 8.5 in., including the printed microstrip transmission lines. Figure 8 illustrates a representative measured radiation pattern from this array. The measured array performances are summarized in Table 2. Clearly, the sequentially fed array gives better VSWR bandwidth, axial ratio, and side-lobe level ( - 24 dB SLL) performance than the conventional feed array. Due to the smaller element spacing for the sequential feed array, the peak gain is slightly lower than the conventional feed array. Note that the antenna size may be further reduced to approximately 6 by 6 in. in size by replacing the feed lines with a PCB feed circuit board behind the radiating patch elements. CONCLUSiON Two different low-gain omni antennas (the drooping dipole and the TM2,-mode circular patch antennas), and two medium gain patch antennas were developed for the successful DBSR demonstrations in Pasadena, California and Buenos Aires, Argentina. These low-cost antennas can be used either indoors or outdoors to receive digital audio signals from the TDRSS satellite. The patch antennas are more conformal than the drooping dipole antennas. For the medium gain antenna, the sequentially arranged CP fed array has a better CP performance over a broader bandwidth than the conventionally fed array. Finally, these antennas have myriad applications in modern satellite or wireless communication systems, such as MSAT, INMARSAT, IRIDIUM, Globalstar, Odyssey, Geostar, etc.

The resonant frequencies of the modes in a cabineted microwave package are investigated by the mode-matching method. The upper region of the package is partitioned into several cabinets using vertical diaphragms of a same depth and of negligible thickness. Numerical results are shown to agree with those of the measurement. The change of the resonant frequencies with the diaphragm depth is presented and explained. It is found that the resonance-free frequency bands can be broadened by suitably designing the positions and the depth of the diaphragms. © 1995 John Wiley & Sons. Inc.