2.1.1 Linearly polarized antennas

The first shape of antenna design is either square with side length = 3.5 mm or rectangular slot with dimensions L = 2.9 mm and W = 4 mm as shown in Figure 2 (a). The antenna reflection coefficient |S11| is shown in Figure 4(a). Figure 4(a) shows that two antenna designs were examined with the same start and end of the operating resonate frequency band from 19.5 to 75 GHz. The square slot shaped antenna has bandwidth discontinuities from 34 to 45 GHz. The second shape included in this study is the circular and elliptical shaped slot as shown in

#### Figure 2.

Different shapes of slot antenna for LP (a) rectangular, (b) circular, (c) triangular, and (d) side view [27].

Figure 3. Shapes of slot antenna for circular polarization (a) rectangular, (b) circular, and (c) triangular [27].

Passive Components for Ultra-Wide Band (UWB) Applications DOI: http://dx.doi.org/10.5772/intechopen.88444


Table 1.

WLAN, WPAN, and W-bands and most of 5th Generation mobile [28–32]. The average radiation efficiency and gain over the entire operating band are about 60% and 6 dBi, respectively [27]. Printed different shapes of slot antenna show small dimensions (Lg Wg) cut at different shapes of slots on larger conductor and are centered above the microstrip-feed line. The microstrip feed line is composed of a straight section of length Lf. To improve the antenna reflection coefficient response, a square stub slot is added with the side length S = 0.6 mm for further improvement in the antenna impedance matching as shown in Figure 2. The width of the tuning line is equal to that of the 50 Ω microstrip line (Wf = 0.56 mm). The optimized

The first shape of antenna design is either square with side length = 3.5 mm or rectangular slot with dimensions L = 2.9 mm and W = 4 mm as shown in Figure 2 (a). The antenna reflection coefficient |S11| is shown in Figure 4(a). Figure 4(a) shows that two antenna designs were examined with the same start and end of the operating resonate frequency band from 19.5 to 75 GHz. The square slot shaped antenna has bandwidth discontinuities from 34 to 45 GHz. The second shape included in this study is the circular and elliptical shaped slot as shown in

Different shapes of slot antenna for LP (a) rectangular, (b) circular, (c) triangular, and (d) side view [27].

Shapes of slot antenna for circular polarization (a) rectangular, (b) circular, and (c) triangular [27].

dimensions of the proposed antennas are shown in Table 1.

2.1.1 Linearly polarized antennas

UWB Technology - Circuits and Systems

Figure 2.

Figure 3.

104

The optimized antennas (all dimensions in mm) [27].

Figure 2(b). The ellipse slot major diameter is W = 4 mm, and different radius ratios were used including the design with a ratio equal to 1.35 as shown in Figure 4(b). The |S11| response shows that the optimal bandwidth at |S11| < 10 dB is obtained using a circular slot shape. The bandwidth extends from 21 to 80 GHz in this case, while for the case of the elliptical slot, the bandwidth starts from 28 GHz and has the same end at 80 GHz as shown in Figure 4(b). The triangular shape is the third slot shape used in this study, and it is compared to trapezoidal as an intermediate stage between a triangle and a rectangle slot as shown in Figure 2(c). Figure 4(c) shows that both of the stated shapes resonate at frequencies higher than the other previous shapes, as it starts from 29 GHz.
