12.3.4 Low Sidelobes

We should also note at this point that the gain function in Figure 12.4 is unrealistic because real gain functions are the result of the addition of fields that are in and out of phase, which results in the desired gain function but also results in a number of sidelobes that provide an amount of gain in other than the intended direction. Figure 12.5 shows the sidelobes in two and three dimensions. Sidelobes are not desirable for a number of reasons: first, they waste power because some power is transmitted in unwanted directions; and second, they cause interference in collocated transmitters receivers.