One-port device

An example of a one-port device is the bulk resonator shown in Figure 6.1, which has a single, planar electrode on each side of a slab of piezoelectric material (these two electrodes together comprise a single port). Most often, the material takes the form of a disk and the electrodes are circular, covering less than the entire surface of the disk. Connection to an external circuit is typically made via a coaxial cable, with one of the two electrodes connected to the shield and the other to the center conductor. This device is known as a resonator because an external circuit (see Section 6.3.3.2) excites the piezoelectric substrate in such a way that a standing wave is set up in the crystal, which thus resonates. 

To complicate matters, appropriately designed two-port devices can readily be operated as resonators (though one-port devices are not practical for use as delay lines). One need only consider the second IDT, located a few acoustic wavelengths fiom the launching transducer, as shown in Figure 6.2, to understand how one- and two-port SAW resonators differ in their fundamental design. A discussion of the function of the second IDT is contained in Section 6.3, Acoustic-Wave Measurement Technology. 

An important general distinction can be drawn between one- and two-port devices that applies to all the measurement schemes discussed throughout this chapter perturbations of one-port devices result in significant changes in device impedance, without major changes in phase for two-port devices, perturbations... 

SCSI Acronym for small computer system interface. A high-speed, system-level parallel interface defined by the ANSI X3T9.2 committee. SCSI is used to connect a personal computer to several peripheral devices using just one port. Devices connected in this way are said to be daisy-chained together, and each device must have a unique identifier or priority number. 

Two-port devices include SAW, FPW, and APM delay lines and the two-port-resonator variations of these devices. For all the delay lines, the transmitted signal S]2 (between ports) is most important Just as in one-port measurements, a network analyzer is the instrument of choice to measure frequency response the setup is depicted in Figure 6.9(a) (page 362). Frequency response can also be measured using the synthesized oscillatorA VM combination shown in Figure 6.9(b). As for the one-port measurements, this setup is most convenient when computer controlled. 

Conceptually, one-port SAW oscillator circuits are very similar to those described for one-port TSM resonators, the principal difference being a significantly higher frequency of operation (100s of MHz rather than a few MHz). Just as for TSM resonators, an external circuit is required that is capable of driving the device at resonance and tracking changes in the frequency of resonance as the device impedance is perturbed. 

One-port FPW measurements, typically using a network analyzer, yield the input impedance of the transducer, the real and imaginary components of which can be used to determine the density and viscosity of a fluid contacting the device. 

Hubs are devices used to link several computers together. They are most often used in lOBaseT Ethernet networks. They are also very simple devices. In fact, they are just multiport repeaters. They repeat any signal that comes in on one port and copy it to the other ports (a process that is also called broadcasting). 

The power divider is a broadband multi-port device which permits the rf inserted in one port to be equally divided between the outputs. The outputs have the same phase and the same amplitude and are highly isolated from each other. Conversely, if two rf signals are put into the output ports of the power divider, they will be added vectorially. Hence the... 

The most efficient and widely used means of generating and detecting surface elastic waves for electronic applications is the interdigital transducer shown in Fig. 2. In its simplest form it consists of a series of parallel metal plate electrodes periodically spaced on the surface of a piezoelectric substrate. The transducer is a three-port device one electrical and two acoustic. When an alternating voltage is applied to its electrical port, time varying electric fields are set up within the substrate, and these excite alternating stress pattern via the piezoelectric effect. The electric field... 

One such device uses a combination of gravitational steric/hyperlayer FFF along the channel axis, and since the channel is mounted at an angle, and not flat on the bench, gravity also causes movement of particles sideways across the channel. A series of outlet ports along the lower edge of the channel continuously removes the separated components. 

A fuel cell system often has interfaces for connecting to a computer or to other electronic monitoring or controlling devices, and at least one port is for connecting to a Universal Serial Bus (USB) for data transfer or other purposes. 

The main geometrical parameters of a coplanar spiral inductor are the strip width (W), the spacing between adjacent turns (S), the internal radius (Rmt), the number of turns (Nt), the spacing to the surrounding coplanar ground plane (Sg), and the metal thickness (VetaO- A relevant frequency-dependent parameter to measure the overall electrical quality of an inductor is the Q factor obtained when one port is shorted the higher the Q factor is, the better the device electrically behaves. The second parameter, often measured to evaluate inductors, is the self-resonance frequency. A selfresonance occurs when the inductive reactance of the device is equal to the parasitic capacitive reactance between the inductor and the substrate, i.e., if Q = 0. 

There are scores of microwave devices that need to be measured. The most common measurements tirat are done are the frequency measurements, but we are also interested in phase measurements depending on the device under test (DUT). We can use various equipments like spectrum analyzer, vector network analyzer, etc. [33]. Most of the devices that we measure will be two-port devices that is, the input is applied at one port and the output is taken at the other port. So we will basically be measuring devices, a group of devices that form a part of tiie system, and microwave circuits. 

Avoid the use of isolation valves on the inlet or outlet of relieving devices. If a shutoff valve (often referred to as a stop valve) is to be added for maintenance purposes, the installer should consult the applicable codes to determine whether it is permitted. A stop valve must have a port area greater than or equal to the inlet size of the relieving device. Twin relieving devices are often installed with positive isolation provided by three-way valves interlocked so that one relieving device is always in service. 

Melt filtration systems can very effectively remove particulate contaminants from polymer melts, for example, continuous systems provided by Process Developments [10] and by Gneuss. Kauferle (Remaker) produced a prototype device capable of causing separation of the melt from high concentrations of aluminium from polystyrene in laminates, or copper from polyethylene in telephone wire, without the need for disposable filter screens. The solid and particle contaminant-free thermoplastic exited from one port on the separation head, while a very high concentration of contaminant embedded in... 

It should be stressed that only those surfaces that actually come in contact with the sample need to be bio-compatible and the major parts of the valve can still be manufactured from stainless steel. The actual structure of the valve varies a little from one manufacturer to another but all are modifications of the basic sample valve shown in figure 13. The valve usually consists of five parts. Firstly there is the control knob or handle that allows the valve selector to be rotated and thus determines the load and sample positions. Secondly, a connecting device that communicates the rotary movement to the rotor. Thirdly the valve body that contains the different ports necessary to provide connections to the mobile phase supply, the column, the sample loop if one is available, the sample injection port and finally a port to waste. Then there is the rotor that actually selects the mode of operation of the valve and contains slots that can connect the alternate ports in the valve body to provide loading and sampling functions. Finally there is a pre-load assembly that furnishes an adequate pressure between the faces of the rotor and the valve body to ensure a leak tight seal. 

These devices have gas and liquid streams which do not merge, i.e. are not fed into each other. Rather, by use of separate ports both phases are passed in their own encasing, e.g. their own micro channel. Thereby, dispersion of the phases is prevented and only one large specific interface is created for mass transfer (different from dispersive micro devices, see, e.g.. Section 5.1.2). The separate guidance of the phases allows to heat the phases separately, usually from the side most distant from the gas/liquid interface. 

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