27 Figure 4-A.—Rectangular-coordinate graph. IN ANSWERING QUESTION 4-29, REFER TO FIGURE 4-A. 4-29.   How many points on the graph can represent the value of 7 radiation units at position 2 of the circle? 1.   One 2.   Two 3.   Three 4.   Four Figure 4-B.—Polar-coordinate graph. IN ANSWERING QUESTIONS 4-30 AND 4-31, REFER TO FIGURE 4-B. 4-30.   Compared with the rectangular- coordinate graph, the polar-coordinate graph has the advantage of showing which of the following antenna characteristics? 1.   Polarization 2.   Radiation pattern 3.   Phase relationship 4.   Gain versus directivity 4-31.   The area enclosed by the radiation pattern is the 1.   lobe 2.   null 3.   axis 4.   coordinate 4-32.   Inserting an inductor or capacitor in series with an antenna is one method of electrically changing the electrical length of an antenna.  What is this method called? 1.   Loading 2.   Inserting 3.   Unloading 4.   Decoupling 4-33.   Many complex antennas are constructed from what basic antenna? 1.   The Marconi antenna 2.   The full-wave antenna 3.   The half-wave antenna 4.   The quarter-wave antenna 4-34.   On an energized half-wave antenna, which of the following electrical conditions exist? 1.   Voltage is maximum at the ends 2.   Voltage is minimum at the ends 3.   Current is maximum at the ends 4.   Impedance is minimum at the center