Answers to Microstrip Lines and Slotlines
Answers to RF Cafe Quiz #50

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Microstrip Lines and Slotlines - RF Cafe Quiz #50This quiz is based on the information presented in Microstrip Lines and Slotlines, by Ramesh Garg, Inder Bahl, and Maurizio Bozzi.

Artech House graciously provided this book.

Note: Some of these books are available as prizes in the monthly RF Cafe Giveaway.

1.  What is a principal requirement for a transmission structure to be suitable as a circuit element in a microwave integrated circuit (MIC)?

d)  It should be planar in configuration.

A planar configuration implies that the characteristics of the element can be determined by the dimensions in a single plane.
(see page 1)

2.  What are two consequences of the non-TEM behavior of microstrip lines?

a)  Dielectric constant and impedance are functions of frequency

Of these two, the variation of the effective dielectric constant is more significant.
(see page 21)

3.  Which of the three drawings below represents the highest performance method of transitioning from coaxial connector to microstrip?

Coaxial connector to microstrip transition (straight inline) - RF Cafe(a)          Coaxial connector to microstrip transition (right angle) - RF Cafe(b)          Coaxial connector to microstrip transition (tapered) - RF Cafe(c)

c)  Tapered transition

With the tapered transition, a 50 Ω impedance is maintained throughout the transition rather than compensating for discontinuities.
(see page 30)

4.  What is full-wave analysis?

b)  Field analysis not invoking quasi-static approximations

Time-varying electric and magnetic fields must be considered when solving wave equations for microstrip (subject to boundary conditions) since the system cannot be fully described in terms of static capacitances and inductances.
(see page 59)

5.  What happens to the temperature of microstrip as the frequency increases?

c)  Dielectric heating causes a temperature rise

Substrate (dielectric) type properties cause varying degrees (pun intended) of heating. Polystyrene, for instance, causes a lot of heating compared to BeO.
(see Figure 2.13 on page 87)

6.  What are examples of discontinuities in microstrip?

d)  All the above

Since discontinuities dimensions are usually much smaller than the wavelength in microstrip, they may be modeled by lumped element equivalents.
(see page 139)

7.  Where does the wave propagate in a slotline?

a)  Along the slot

In a slotline, the wave propagates along the slot with the major electric field component oriented across the slot in the plane of metallization on the dielectric substrate.
(see page 239)

8.  What is a Defected Ground Surface (DGS)?

c)  An intentional deviation from a continuous flat ground plane.

In DGS, the ground plane is intentionally modified to improve the frequency response of the component.
(see page 305)

9.  What is the distinguishing feature of a coplanar waveguide?

b)  All elements are collocated on the same surface of the substrate

The term "coplanar" is used for those transmission lines/waveguides where all the conductors reside in the same plane; namely, on the top surface of the substrate.
(see page 347)

10.  What is the name given to a configuration whereby two transmission lines are placed parallel to each other and in close proximity?

a)  Coupled line

In such a configuration there is continuous coupling between the electromagnetic fields of the two lines.
(see page 433)

Posted   June 17, 2013