6.4 Multiband antennas

Multiband antennas can be produced by designing slots using different frequencies. Figure 15 shows the slots that are used for two frequencies. It is noted that we

Figure 15. (a) Design of dual-band antenna. (b) Band result.

cannot differentiate between the 5.4 and 5.8 GHz slots since they are plotted mixed. This will not effect to the gain since all slots are designed using a same beamsquint value. Research on this topic can be as follows: firstly, a study on how to correctly place different frequency slots, so that the correct placement will not increase antenna reflections. Secondly, a study of how far two different bands or more can be separated since a different band needs a different feeder structure. However in multiband antennas, we use a same feeder structure so that it will effect to the increase of reflection, such that different bands cannot be separated too far.
