Showing papers on "Return loss published in 1978"
TL;DR: In this paper, a quasi-optical frequency multiplexer based on a blazed diffraction grating is studied, which is an efficient channel-dropping filter well suited to use in the millimeter wave region.
Abstract: A quasi-optical frequency multiplexer based on a blazed diffraction grating is studied. Experimental data, supported by semi-quantitative theoretical considerations, show that the multiplexer is an efficient channel-dropping filter well suited to use in the millimeter wave region. A feature of the grating multiplexer which sets it apart from conventional designs is its ability to drop several channels using a single frequency-selective element, namely, a diffraction grating. This economy of hardware results in a simple, compact structure. The channels of the experimental multiplexer have typical bandwidths of ~540 MHz with loss of ~1 dB. The width of the impulse response at half amplitude is ~1.5 ns. Return loss within a channel is typically 15-20 dB. Comparisons with other millimeter wave multiplexer designs are discussed.
19 citations
01 Sep 1978
TL;DR: In this paper, two types of highly efficient transducer arrays are described which couple acoustic energy into the samples imaged in nondestructive testing applications, which couple the acoustic energy from the high impedance ceramic to water, used as the transmitting medium.
Abstract: Two types of highly efficient transducer arrays are described which couple acoustic energy into the samples imaged in nondestructive testing applications. The first type of array utilizes fully slotted, double quarter-wave matched elements to couple the acoustic energy from the high impedance ceramic to water, which is used as the transmitting medium. One such 180 element linear array operating at a center frequency of 3.5 MHz has 11 dB return loss, 45% 3 dB bandwidth, and k13" 3 dB acceptance angle. Experimental results with an improved double quarter-wave matched, fully slotted array are described including 9 dB return loss, 65% 3 dB bandwidth, and +44" 3 dB acceptance angle. A second type of high efficiency array uses unslotted ceramic permanently attached to a high impedance buffer block which is coupled directly to the load. Individual array elements are formed by depositfon of electrodes on the monolithic slab of ceramic. One longitudinal wave test array mounted on aluminum is reported with a half power beamwidth of +37".
8 citations