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

varieties of SRR structures that have been reported in the literature like square,

The designed antenna structure is composed of three connected semicircular arc monopoles with circular patch fed by microstrip transmission line and modified half circular shaped ground plane as shown in Figure 13. The initial design is validated and optimized by simulating the proposed antenna. The proposed antenna is designed on FR4 substrate with height 1.6 mm, dielectric constant ε<sup>r</sup> = 4.6, and loss tangent tan δ = 0.02. The antenna is fed by a 50-Ω transmission line (TL).

The main design parameter for UWB antenna is the lower frequency edge (fL) rather than the resonance frequency (fr) as in Eq. (7). The lower band edge frequency of the designed antenna is calculated approximately by equating their surface area with that of an equivalent cylindrical monopole antenna of the same height as given by [45]. If R1 is the height of the planar monopole antenna in cm, which is taken the same as that of an equivalent cylindrical monopole, and r in cm is the effective radius of the equivalent cylindrical monopole antenna, which is determined by equating area of the planar and cylindrical monopole antennas, then the

<sup>f</sup> <sup>L</sup> <sup>¼</sup> <sup>7</sup>:<sup>2</sup>

Lf þ R<sup>1</sup> þ r

Evolution of the design steps of the proposed printed monopole. (a) First step, (b) second step, (c) third step,

GHz (7)

circular, triangular, omega, and labyrinth resonator [47].

3.2.2 Design and EM models with parametric study

lower band edge frequency is given as [45]:

Figure 13.

112

(d) fourth step, (e) fifth step, and (f) sixth step [45].

where Lf is the length of the 50 Ω feed line in cm.

3.2.1 Antenna structure and geometry

UWB Technology - Circuits and Systems

The design started with first semi arc 1800 with radius 25 mm and with 5 mm width modified ground plane Lg = 19 mm as shown in Figure 13(a), and related |S11| is shown in Figure 14. To improve the bandwidth, second semi sector with radius 17 mm and width 3.5 mm as shown in Figure 13(b) with the same previous dimensions is added to add second resonant as shown in Figure 14. Third sector with radius 7.5 mm and width 2.5 mm is added, and keeping previous dimensions the same as shown in Figure 13(c), a third resonance is achieved as shown in Figure 14. Another extension of the bandwidth is done by adding circular disk with radius 4 mm as shown in Figure 13(d), and related reflection coefficient is shown in Figure 14. Modified ground plane is used to improve the bandwidth with ellipse with major radius 25 mm and minor radius 15 mm, as shown in Figure 13(e), is suggested, and the related reflection is shown in Figure 14. The evolution of designing the proposed configuration is demonstrated in Figure 13(f), and their corresponding optimized dimensions are tabulated in Table 3. The antenna gain and radiation efficiency are also studied as shown in Figure 15. The proposed antenna with SRR achieves an average gain of 7.5 dBi, and the peak realized gain around 22.5 dBi at 7.5 GHz as shown in Figure 15(a). The designed antenna gain without SRR achieves an average gain around 5.5 dBi, while peak gain realized is 15 dBi at 8.5 and 10 GHz. The gain of the designed antenna is also measured, and there is good agreement between results especially at high frequency. The antenna radiation efficiency was simulated for both monopole antennas with and without SRR by using wheeler cap method [44]. The average radiation efficiency is around 70% over the operating bands for PMPA with SRR and around 65% without SRR as shown in Figure 15(b).

Figure 14. Design procedures of the proposed antenna [45].


Table 3. Dimensions of the proposed antenna (all dimensions in mm) [45].

application and FCC UWB regulation. It is fabricated by using photolithographic technique, and the measurements were carried out by using a Rohde & Schwarz

A filter is a two-port network that is used to control frequency response in a system. Filters can be classified into three main groups of active (requiring external power source), passive (no need for external power), and hybrid filters. Microwave systems are often involved with power conservation and noise control, and therefore, active filters are generally considered as last alternative. Passive filters are, however, further divided into lumped and distributed. The former consists of lumped components (including capacitors, inductors, resistors, and magnetic and electromechanical components), and the latter comprises a periodic conducting structure with various dielectric media. Inductors and capacitors form LC filters whereas resistors and capacitors form RC filters. Although resistors introduce loss to the circuit, they are generally used for broad banding (matching) purposes.

4.1 UWB band-pass filter with sharp tuned notched band rejection based on

the length L6 of the stub. The total area of the filter is 16.4 5 mm<sup>2</sup>

makes it suitable for modern applications which need miniaturization.

A compact UWB BPF with reconfigurable notch bands based on CRLH transmission line unit cell has been designed, simulated, and fabricated [48]. Two packages of software are used, namely, CST MWS and 3D EM commercial software HFSS version 13.0. The simulated and measured results are comparable. This filter has the advantage of very small size, and it also has four notched frequencies in its passband. The notched bands suppress the narrow-band services such as WLAN and WiMAX. One can control the center frequency of the notched band by varying

The proposed filter is designed based on the filter described in Ref. [49] but with a new contribution which is notched controllable tunable four sharp rejection bands by adjusting the length of the coupling stub using diode switching matrix tools

Figure 18 shows the proposed microstrip UWB-BPF with tuned notched passband based on CRLH transmission-line unit cell. The optimized dimensions of the

The dimension of the multi-mode section as shown in Figure 18 is 4.4 1.5 mm, the length of the shunted inductive line is 3.1 mm, and the overall dimension of the

i. The notched band depends on the coupling stub (L6) in the output section.

ii. The notch frequency of the filter can be changed by adjusting the length of the coupling stub L6. As L6 increases, the center notch frequency decreases as shown in Table 5. The length L6 is controlled by using switching matrix equipment (mini circuit) where the character D refers to the diode.

proposed filter is 16.4 5.0 mm. Based on the above description, the design

. This small area

ZVA67 vector network analyzer from 50 MHz to 67 GHz.

Passive Components for Ultra-Wide Band (UWB) Applications

DOI: http://dx.doi.org/10.5772/intechopen.88444

CRLH transmission-line unit cell

4.1.1 Proposed filter design

(instead of using PIN diodes).

procedure can be as follows:

115

proposed filter are as shown in Table 4.

4. UWB filter

### 3.2.3 Implementation and measured results

The prototype of the proposed antenna is shown in Figure 16. The performance parameters of the fabricated designed antennas are measured. The comparison results of simulated and measured input |S11| of the antennas are found to be in very good agreement, as shown in Figure 17. The 10 dB bandwidth of the designed monopole antenna with SRR extended from 1.5 to 11 GHz to cover most wireless

application and FCC UWB regulation. It is fabricated by using photolithographic technique, and the measurements were carried out by using a Rohde & Schwarz ZVA67 vector network analyzer from 50 MHz to 67 GHz.
