6.2 The use of background as radiating element

Theoretically, only radiating elements that are used as place for slots, as shown in Figure 13a. The background always functions as conventional background to

radiating elements. Our hypothesis is that the background can be used to draw slots on it, as shown in Figure 13b. This will result in a dual-beam antenna as shown in Figure 13c. Of course, the gain will decrease by 3 dB compared to the originally

Multibeam antennas can be produced by designing slots using different beamsquint values. The slots are grouped and placed based on its beamsquint values. Figure 14a shows the slot design of two beams, and Figure 14b shows its beams. Things to note are that there will be a slot coupling between adjacent slot groups, which will lessen the sharpness of beams or the gains. Therefore, it is needed to put the slot group not too close together such that we get satisfied gains.

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

single-beam antenna, since the power is divided into two beams.

6.3 Multibeam antennas

(a) Design of dual-beam antenna. (b) Beam result.

Figure 13.

Figure 14.

(a) Radiating element. (b) Background. (c) Radiation pattern.

Radial Line Slot Array (RLSA) Antennas DOI: http://dx.doi.org/10.5772/intechopen.87164

6.4 Multiband antennas

197

Figure 12. (a) Concentrated slots. (b) Cut antennas. (c) Leakage power.

reflection coefficient of small-RLSA antenna. The use of extra high beamsquint

Telecommunication Systems – Principles and Applications of Wireless-Optical Technologies

Space to be explored for RLSA antennas has remained wide, since only few researchers study this topic. This is due to the drawing slots of RLSA antennas that are difficult without using computer programmes. This is unlike microstrip antennas which are easy to draw since their shape is simple. Moreover, it is more difficult to fabricate RLSA antennas compared to microstrip antennas since there is no row material that is ready to be cut or to be formed. This is unlike microstrip, which can

use many types of boards such as FR4. Therefore, due to these reasons, less researchers are interested in studying RLSA antennas than microstrip antennas. Below, several research ideas in the field of RLSA are presented to be explored

radiating elements, and leaving other areas vacant from slots, as shown in

The use of extra high beamsquint results in concentrated slots in a certain area of

Our hypothesis is that since the vacant area is not useful, then it can be cut off, thus resulting in a smaller antenna, as shown in Figure 12b. We have studied that definitely there will be an effect of the cut, which is a leakage power along the cutting line, shown in Figure 12c. This leakage power reduces the antenna gain. However, the antenna gain will not be affected significantly since the power density within the cut antenna will increase, thus also will increase the gain, then counter-

Theoretically, only radiating elements that are used as place for slots, as shown in Figure 13a. The background always functions as conventional background to

angle underlies the naming of extreme beamsquint technique.

deeper, especially for doctoral dissertation and master thesis.

6. Future development of RLSA antennas

ing the decrease gain due to the leakage power.

(a) Concentrated slots. (b) Cut antennas. (c) Leakage power.

6.2 The use of background as radiating element

6.1 Cutting antennas

Figure 12a.

Figure 12.

196

6.1.1 Concentrated slot area

Figure 13. (a) Radiating element. (b) Background. (c) Radiation pattern.

#### Figure 14.

(a) Design of dual-beam antenna. (b) Beam result.

radiating elements. Our hypothesis is that the background can be used to draw slots on it, as shown in Figure 13b. This will result in a dual-beam antenna as shown in Figure 13c. Of course, the gain will decrease by 3 dB compared to the originally single-beam antenna, since the power is divided into two beams.
