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General Class Exam Question Pool

effective 7/01/2015 thru 6/30/2019

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2015-G9C: Directional antennas

2015-G9C01: Which of the following would increase the bandwidth of a Yagi antenna?

Larger diameter elements

Closer element spacing

Loading coils in series with the element

Tapered-diameter elements



2015-G9C02: What is the approximate length of the driven element of a Yagi antenna?

1/2 wavelength

1/4 wavelength

3/4 wavelength

1 wavelength



2015-G9C03: Which statement about a three-element, single-band Yagi antenna is true?

The director is normally the shortest element

The reflector is normally the shortest element

The driven element is the longest element

Low feed point impedance increases bandwidth



2015-G9C04: Which statement about a three-element, single-band Yagi antenna is true?

The reflector is normally the longest element

The director is normally the longest element

The reflector is normally the shortest element

All of the elements must be the same length



2015-G9C05: How does increasing boom length and adding directors affect a Yagi antenna?

Gain increases

Beamwidth increases

Front to back ratio decreases

Front to side ratio decreases



2015-G9C06: What configuration of the loops of a two-element quad antenna must be used for the antenna to operate as a beam antenna, assuming one of the elements is used as a reflector?

The reflector element must be approximately 5 percent longer than the driven element

The driven element must be fed with a balun transformer

There must be an open circuit in the driven element at the point opposite the feed point

The reflector element must be approximately 5 percent shorter than the driven element



2015-G9C07: What does "front-to-back ratio" mean in reference to a Yagi antenna?

The power radiated in the major radiation lobe compared to the power radiated in exactly the opposite direction

The number of directors versus the number of reflectors

The relative position of the driven element with respect to the reflectors and directors

The ratio of forward gain to dipole gain



2015-G9C08: What is meant by the "main lobe" of a directive antenna?

The direction of maximum radiated field strength from the antenna

The magnitude of the maximum vertical angle of radiation

The point of maximum current in a radiating antenna element

The maximum voltage standing wave point on a radiating element



2015-G9C09: How does the gain of two 3-element horizontally polarized Yagi antennas spaced vertically 1/2 wavelength apart typically compare to the gain of a single 3-element Yagi?

Approximately 3 dB higher

Approximately 1.5 dB higher

Approximately 6 dB higher

Approximately 9 dB higher



2015-G9C10: Which of the following is a Yagi antenna design variable that could be adjusted to optimize forward gain, front-to-back ratio, or SWR bandwidth?

All of these choices are correct

The physical length of the boom

The number of elements on the boom

The spacing of each element along the boom



2015-G9C11: What is the purpose of a gamma match used with Yagi antennas?

To match the relatively low feed point impedance to 50 ohms

To match the relatively high feed point impedance to 50 ohms

To increase the front-to-back ratio

To increase the main lobe gain



2015-G9C12: Which of the following is an advantage of using a gamma match for impedance matching of a Yagi antenna to 50 ohm coax feed line?

It does not require that the elements be insulated from the boom

It does not require any inductors or capacitors

It is useful for matching multiband antennas

All of these choices are correct



2015-G9C13: Approximately how long is each side of the driven element of a quad antenna?

1/4 wavelength

1/2 wavelength

3/4 wavelength

1 wavelength



2015-G9C14: How does the forward gain of a two-element quad antenna compare to the forward gain of a three-element Yagi antenna?

About the same

About 2/3 as much

About 1.5 times as much

About twice as much



2015-G9C15: Approximately how long is each side of the reflector element of a quad antenna?

Slightly more than 1/4 wavelength

Slightly less than 1/4 wavelength

Slightly less than 1/2 wavelength

Slightly more than 1/2 wavelength



2015-G9C16: How does the gain of a two-element delta-loop beam compare to the gain of a two-element quad antenna?

About the same

3 dB higher

3 dB lower

2.54 dB higher



2015-G9C17: Approximately how long is each leg of a symmetrical delta-loop antenna?

1/3 wavelength

1/4 wavelength

1/2 wavelength

2/3 wavelength



2015-G9C18: What happens when the feed point of a quad antenna of any shape is moved from the midpoint of the top or bottom to the midpoint of either side?

The polarization of the radiated signal changes from horizontal to vertical

The polarization of the radiated signal changes from vertical to horizontal

There is no change in polarization

The radiated signal becomes circularly polarized



2015-G9C19: How does antenna gain stated in dBi compare to gain stated in dBd for the same antenna?

dBi gain figures are 2.15 dB higher than dBd gain figures

dBi gain figures are 2.15 dB lower then dBd gain figures

dBi gain figures are the same as the square root of dBd gain figures multiplied by 2.15

dBi gain figures are the reciprocal of dBd gain figures + 2.15 dB



2015-G9C20: What is meant by the terms dBi and dBd when referring to antenna gain?

dBi refers to an isotropic antenna, dBd refers to a dipole antenna

dBi refers to an ionospheric reflecting antenna, dBd refers to a dissipative antenna

dBi refers to an inverted-vee antenna, dBd refers to a downward reflecting antenna

dBi refers to an isometric antenna, dBd refers to a discone antenna





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