Abstract

UWB technology brings the convenience and mobility of wireless communications to very high-speed interconnects in the home and office due to the precision capabilities combined with the low power. This makes it ideal for certain radio frequency sensitive environments such as hospitals and healthcare as well as radars. UWB intrusion-detection radar is used for detecting through the wall and also used for security with fuse avoidance radar, precision locating and tracking (using distance measurements between radios), and precision time-of-arrival-based localization approaches. The FCC issued a ruling in 2002 that allowed intentional UWB emissions in the frequency range between 3.1 and 10.6 GHz, subject to certain restrictions for the emission power spectrum. Other definitions for ultra-wideband range of frequency are also used such as any device that has 500 MHz bandwidth or fractional bandwidth greater than 25% is considered an UWB enable high data rate to be transferred with a very low power that does not exceed 41.3 dBm.

The main advantage of UWB technology is that it has the ability to transmit high bandwidth data between various devices with distances in the order of 10 m far from each other, such as home or office appliances with high sped transfer which may reach 1Gbit/s.

There are many components that are designed and used in UWB systems such as antennas, power dividers/combiners, filters (LPF, BPF, etc.), rectennas, filtennas, etc.

Many types of antennas are able to achieve UWB. Monopole antennas are usually used as linearly polarized antennas which prove to be the best whelming choice for use in various automobiles and mobile equipment. Log parodic and Yagi antennas are other types of UWB with high gain. Electromagnetic band gap (EBG) structure as defected ground or split ring resonator are also used to improve the antenna bandwidth and achieve UWB.

Many UWB filters are designed and implemented using modern techniques such as meta-material, tuning stubs, defected ground structures, modified CMRC (compact microstrip resonant cell), etc. These filters may be switchable or tunable in order to make notch frequencies within the passband to provide interference immunity from unwanted radio signals, such as wireless local area networks (WLAN) and worldwide interoperability for microwave access (WiMAX) that cohabit within the UWB spectrum.

The need of compact multiband filtenna (filter combined with antenna) with the ability of covering the current standards at the microwave band and the next generation standards at the millimeter wave band simultaneously is raising. Also, the operation of cognitive radio and self-adaptive systems need to dynamically monitor the frequency spectrum in search of the unused licensed channels. All these applications need different types of filtenna which may be fixed, switchable or tunable that can operate in the

UWB range of frequency and also with narrow band modes to cover for example UWB/WiMAX applications.

Due to UWB technology and using nanosecond pulses in many applications such

In UWB band-pass filters, one can use many techniques in their design such as composite low-pass and high-pass structure [11], multiple-mode resonator structure [14], and short-circuited stub [12, 13]. Because UBW components occupy a large bandwidth which may be extended from 3.1 up to 10.6 GHz, interference attenuation due to coexisting services should be avoided. This is the motivation of using switchable or tunable narrow band notch within the passband of the UWB filter [15–17]. This may be achieved by many methods such as using additional notch resonators [18], embedded open stubs [19], asymmetric coupled fed lines [20], out-of-phase transmission cancelation [21], meander-line slots [22], and short-circuited stub resonators in a multilayer periodical structure [23].

To deal with different co-existed communication needs, the reconfigurable notch band implementation is required, but little research is concentrated on a UWB BPF with reconfigurable, switchable, or tunable notch bands as in [24–26]. An HFSS, FEM-based, 3D full wave electromagnetic solver simulator by ANSYS as well as CST were used for the design of all designed antennas. Also, ADS was used to design the filters and filtennas in addition to the above electromagnetic

This chapter describes one example for printed millimeter wave antenna implementations, illustrating specific and interesting particular solutions for their design and two shapes of single UWB antenna in radio frequency range. In addition, two examples of UWB filters and one example of UWB filtennas are introduced.

Classical antenna as reflector, lens, and horn type antennas have been used in millimeter-wave devices. But for low-cost, these antennas are commercial expensive devices, bulky, heavy and require complex feeding in an array system. In addition, they are very difficult to integrate with solid-state devices [6–9]. However, the microstrip antennas (MPAs) are narrow bandwidth and are large size

Three different types of broad multi-band linearly and circularly polarized slot antennas (rectangular-, circular-, and triangular-shaped slots) for millimeter wave wireless communication applications [27] are shown in Figures 2 and 3, respectively. Proposed antenna consists of a slot radiator on the top metal layer and coupled to a rectangular dielectric resonator above the slot. The conventional microstrip-line-feed is used for different shapes of slot antennas. Final designed antennas were fabricated, and their characteristics were measured as reflection coefficient. The bandwidth of |S11| < 10 dB was extended from 19.5 up to 75 GHz. This band covers wireless MM-wave applications and wireless networks, and the

2.1 UWB slot antennas for linear and circular polarizations

as military and biotechnology applications [6–8], the need for very broadband circularly polarized antenna has emerged. These UWB CP antennas are the substitution of the narrowband CP microstrip patch antennas [8–10].

One of the most commonly used devices to control the spectrum of radio frequency signals and necessary in an UWB radio system whether in impulse system or multiband system, in order to reconfigure the UWB signal to satisfy the spectrum regulation is the filter. Ultra-wide band (UWB) band-pass filter that achieves ultra bandwidth from 3.1 to 10.6, low insertion loss, low and flat group delay, out-band

performance can be considered a well-designed UWB band-pass filter.

Passive Components for Ultra-Wide Band (UWB) Applications

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

simulators in this chapter.

2. UWB millimeter wave antenna

about half-wavelength structures.

103

Keywords: ultra-wide band (UWB), monopole antenna, UWB filters, filtenna, electromagnetic bandgap structure (EBG), log parodic
