**2.2 Antenna design**

*Advanced Radio Frequency Antennas for Modern Communication and Medical Systems*

tion of malignant tissue characteristics as it size, shape, placement, … [3].

we will use the slot insertion at the level of the radiating element. The design procedure followed consists of three steps:

• The first step is to develop a structure with ULB characteristics.

an antenna capable of meeting these requirements.

oped in terms of adapting the impedance

**2. Design of a UWB coplanar fed antenna**

biomedical imaging, and HD communication.

power emission level −41.3 dBm/MHz [4].

*2.1.1 Matching and efficiency*

width more than 20% [4, 5].

**2.1 Ultra wide band**

• The third step is to develop an antenna network.

Breast cancer is the second deadly cancer for women, for more efficiency and an early detection, the biomedical field need new systems that should be safe, comfortable and sensible [1, 2]. The medical field already has its methods to detect breast cancer like X-ray mammography, magnetic resonance imaging (MRI), as efficient as those techniques are they are missing between 10 and 30% [2] of very early breast cancer stages. The UWB microwave imaging is one of the techniques that has been developed, in the Hunt for the next techniques that will detect breast cancer in its early stages. The basis for microwave detection is to compare between the dielectric properties of a normal tissue and cancerous tissue, the result of the comparison gives a predic-

The second part of this chapter, I present a microstrip antenna that we offer is circular in shape and, a priori, has a low gain and a narrow bandwidth. To meet the requirements of our specifications would be to expand the bandwidth. For this reason, we have developed a design methodology, which has enabled us to develop

The reduction in size is also a consideration to take into account when designing this antenna, which would allow it to be more easily integrated into the system and reduce the size. For this, the certain techniques are used. Among these techniques,

• The second step is used to optimize the performance of the structure devel-

UWB is defined as a system with a very large band, this large spectrum comes usually with some advantages as a low power, high debit of data, high time resolution, low-cost and an ease of implementation, resistance to interference and so on. Those advantages opened a wide range of UWB application to radar detection,

The definition of UWB is not a special one, the FCC (Federal Communication Commission) [4] defines it as a system with a bandwidth larger than 500 MHz or larger than 20% if we are working whit the relative bandwidth W/fc (W is the width of the band and fc is the carrier frequency). The UWB is being defined by its very large band that is 7.5 GHz between 3.1 GHz and 10.6 GHz for a limitation of the

The UWB communication systems uses a very short pulse duration of tens hundreds of nanoseconds, and sense the pulse and the bandwidth are inversely proportional, the shorter pulses is the wider the spectrum is going to be.

Antennas would match the UWB requirements if it have a bandwidth greater than 500 MHz defined at −10 dB according to the FCC, or to have a relative band-

**78**

This section is dedicated to the design and the performance of the proposed antenna. The design proposed is a notched coplanar antenna. The geometry of the antenna consisted of a 25 × 30 mm2 , Rogers RT5850 substrate with *ε*r = 2.2 and thickness h = 3.175 mm. The top part of the antenna is a circle with two cutouts of 90° each. The structure of the antenna is shown in **Figure 1**.

The two main characteristics that effect the performance of the antenna was the inner radius of the circle R and the laminate thickness. The gap between the transmission line and the ground structure was optimized so that the antenna's impedance can match a 50 Ω SMA port.
