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Mobile and wireless communications network layer and circuit level design Part 7

Tham khảo tài liệu 'mobile and wireless communications network layer and circuit level design part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Microstrip Antennas for Mobile Wireless Communication Systems 171 4.4 PIFA structures for multiband and compact size applications 4.4.1 Rectangular PIFA shape with U-shaped slots A practical method to design a single feed multiband PIFA that covers both the cellular and non cellular bands is developed Dalia Nashaat et al 2005 Hala Elsadek 2005 R. Chair et al 1999 . From the commercial point of view there are now different frequency bands for portable cellular non cellular devices as the conventional 0.9GHz GSM band for mobile phones and 1.8GHz DCS band for wireless cellular applications. Furthermore the Bluetooth wireless technology at 2.4 GHz is already applied in many portable devices and in most wireless communication systems as mobile phones laptops PDAS car stereos audio speakers toys etc Bluetooth information web site . Moreover the band of WLAN at 5.2GHz is being applied in some applications. The compact and multiband functionality is not the only required demand in such antenna systems for wireless communication applications but also other characteristics should be satisfied as small size light weight omni directional radiation pattern reasonable gain and acceptable bandwidth. Quad band PIFA with single coaxial probe feeding is investigated. Foam substrate is used for light weight rigid structure and easy shielding purposes. Three U-shaped slots are added with certain dimensions and at appropriate positions for operation at the aforementioned four frequency bands. The size reduction is 30 from conventional quarter wavelength PIFA. Additional reduction by 15 is achieved by adding a capacitance load in the vertical direction. The impedance bandwidth is fairly acceptable. The antenna gain is satisfactory and the radiation pattern is quasi isotropic at the respective four bands of interest. The proposed concept of adding U-shaped slots is a distinct advantage of the design since the bands of operation are independent on each other except the small controllable