Review Questions

1.	What determines the electrical characteristics of coaxial cable?(Select two options.) Capacitance Dielectric material composition Dielectric material physical dimensions Velocity of propagation
2.	What is a broadcast interval in reference to an active tag? The time between signals that are sent out from the tag The amount of time between reads from an active reader The time between each wavelength None of the above
3.	A pharmaceutical company that manufactures cough syrups would like to track every bottle manufactured in the supply chain. It needs to select a tag that can read through liquids at a low cost. What tag would you recommend? Microwave UHF HF LF
4.	In a supply-chain application, you like to track cases and pallets made of corrugate. Each pallet has about 80 cases. What type of tags would you use? Thermal label LF HF UHF
5.	You go to a hardware store and make a copy of your car keys. You then try to start your vehicle with the duplicate keys, but the car does not start. What kind of tag needs to be present in the duplicate key? Key ring LF HF Active tag
6.	What does FCC regulation part 15 specify? Frequency hopping Antenna gain Cable loss standards Tag data requirements
7.	What is cross talk? Waiting for one reader to read before another begins reading Reading outside of the intended interrogation zone Reading half of one tag and half of a different tag None of the above
8.	Which use case has the longest dwell time? Pharmaceutical manufacturing line Highway tollbooth Forklift unloading a trailer Stretch-wrap machine
9.	What is the best type of antenna to use for a UHF system that is reading laptops as personnel carry them through an entrance door in their briefcases? Linearly polarized Circularly polarized Inductively coupled Declonian design
10.	What is the best choice for a 30-foot cable run from a UHF reader to a linearly polarized 6 dB gain antenna? LMR-100 LMR-400 CAT-6 All of the above
11.	What is the most complex component in an RFID network? The tag The antenna The reader The cable
12.	Where would you use a UHF RFID network? (Select two options.) Pharmaceutical item-level tracking Luggage tracking Livestock tracking Retail store supply chain
13.	What must you consider when selecting an antenna for a UHF system? Tag orientation Distance to be read Speed of tags through the interrogation zone All of the above
14.	All middleware can control which of the following reader functionalities? Data filtering Light stack functionality Motion detectors Manual triggering of reads
15.	When does a passive tag receive its power to communicate? When it is plugged into a battery When it is triggered by a motion detector When it enters the radiated field of a matched RFID reader All of the above
16.	What is the most common operating frequency for an active RFID tag? 7 MHz 433 MHz 915 MHz 13.56 MHz
17.	What does RFID middleware do? Filter and smooth data Provide a GUI to end users Print to RFID labels Monitor the health of the RFID network
18.	What is a continuous wave? A wave that has the same power throughout its lifespan A wave that reflects off a surface and comes back out of phase The turbulence created by multiple frequencies None of the above
19.	Which of the following best explains the skin effect relative to cable performance? The thicker the skin, the more ribbing it can take. The higher the frequency, the more signal travels along the outer surface of the conductor. Mismatching of impedance will result in a melting of the cable's outer surface. If the skin is rubbed too thin, the signal will short to ground.
20.	Why do readers matter the most in an RFID network? (Select two options.) They are the only system component you have control over. They are the most complex system component. They are expensive to both buy and maintain. They last only a few months.

Answers

1.	B, C. Capacitance and velocity of propagation are two of the characteristics that are important in choosing the right coaxial cable. However, the key performance drivers are capacitance and the impedance which are determined by B and C the correct answer.
2.	A. An active tag, with its on-board battery, is set to broadcast its information at a certain interval so that an interrogator knows that a tag is in the field and can retrieve whatever data happens to be on that tag.
3.	C. HF tags are less susceptible to liquids and can be manufactured in bulk at a lower cost. Hence HF tags would be the best choice for the pharmaceutical company.
4.	D. Normally in a supply-chain use, case pallets are read at dock doors or stretch wrappers. The pallets and cases are about 3 to 6 feet away from the read point. Also the pallet has over 80 cases; hence UHF will be the best choice. The second reason for selecting UHF is because of the low tag costs.
5.	B. Current car manufacturers use LF tags in the butt of the key. Car immobilizer circuits present in the car ignition circuits query the tag in the keys provided by the car manufacturer. Usually keys made at hardware stores won't work because they do not have LF tags embedded in the key. Such keys can be obtained only from the car dealer or manufacturer.
6.	A. FCC regulation part 15 states that in the UHF ISM band a reader must hop pseudo-randomly across at least 50 channels in the frequency range 902–928MHz.
7.	B. Cross talk occurs when multiple interrogation zones are set up in close proximity to each other, and the system is poorly designed. If the system is not properly designed, a reader in one portal could unintentionally read tags going through an adjacent portal.
8.	D. The stretch-wrap machine usually turns a pallet for several revolutions, plus getting on and off. This keeps the tags in the interrogation zone for an extended period of time and also has the added benefit of moving the tag orientation to ensure a high probability of read success.
9.	B. You are not sure what orientation the tag is likely to be presented to the antenna, because people will carry their laptops in different bags, and will hold them on their person in a different manner. Therefore, you want to limit the system's sensitivity to orientation and should install a circularly polarized antenna that is made for UHF.
10.	B. The higher the LMR number, the more shielding or insulation to prevent loss on long cable runs. LMR-400 would provide adequate insulation for a long cable run.
11.	C. The reader has many sophisticated components that turn a digital signal into an analog wave, listen for a much weaker signal in response, and turn that signal into useful information. It is by far the most complex part of an RFID network.
12.	B, D. If there are large items to be tracked at fast speeds over relatively long distances, they are likely candidates for UHF tracking. Pharmaceutical item level is best suited for HF, where the metal and liquids would not cause an issue, and livestock is also suited for HF because there is a lot of liquid associated with living beings.
13.	D. The three primary criteria of antenna selection will drive whether you choose a linearly polarized or circularly polarized application.
14.	A. The only true commonality in middleware is the ability to filter out data and present it up to the application layer. Other capabilities such as device configuration, peripheral control, and monitoring are not common to the various programs.
15.	C. A passive tag receives its power from the energy output broadcast by a matched RFID reader. A UHF reader will not power up an HF tag, and vice versa.
16.	B. Most active RFID systems are based on a standard working at 433 MHz.
17.	A. RFID middleware at its basic level filters and smooths the data coming off an RFID reader before it gets sent up to a business application such as a warehouse management system (WMS) or enterprise resource planning (ERP) software.
18.	D. A continuous wave is an electromagnetic wave that has both the same amplitude and the same frequency. If you were to measure it as a visible graph, you would see the same height and width constantly repeating itself.
19.	B. Lower frequencies are transmitted inside the center conductor, and therefore if it is a lower-frequency system, the choice of material for the core becomes more important than the outer conductive surface.
20.	B, C. The largest capital outlay and the most variation in the system occur when selecting the RFID reader. At an average price ranging from $700–$4,000, they are also the single most expensive piece of equipment in the network.