Small‐size printed loop antenna for penta‐band thin‐profile mobile phone application

Abstract

figure) is similar to the AR curve in ϭ 0Њ plane. It is seen that in the peak gain direction ϭ 90Њ, where AR ϭ 1 (or 0 dB) in theory, the measured value AR ϭ 1.1 (or 0.8 dB) is quite close. Within the beamwidth region (or Ϫ3 dB-angular sector) of the gain radiation pattern AR is less than 1.41 or 3 dB, which is well within the customary requirements for medium-gain antennas with circular polarization [9]. CONCLUSIONSIn this article a folded-wire X antenna is introduced and applied for construction of a low-profile directive flat-reflector antenna. The two orthogonal input ports of the X antenna produce the same gain radiation patterns but different orthogonal polarizations. Both ports of the studied UHF X antenna model have equal input impedances of about 160 ⍀ at resonance. Because of its structural symmetry, the X antenna possesses very large inter-port and far-field crosspolar isolations. The single-port fed X antenna behaves like a half-wave dipole and the double-port fed X antenna acts as an array of two crossed dipoles.The low-profile X antenna located in front of a flat reflector has a very simple feed circuit, where both ports are connected to two 50-⍀ coaxial cables (loads) in balun-like manner. Compared with the standard reflector antenna with an active element (dipole, loop, and X antenna) located at a distance of 0.25-0.35 wavelengths, the low-profile reflector X antenna features about 2.5-3.0 dB higher gain, and thus, possesses an useful super-directivity. In addition, the reflector X antenna has much better input and cross-polar isolation compared with the similar low-profile array of two folded half-wave dipoles located in front of the same-size flat reflector.Future applications of the folded-wire X antennas may include linear or circular polarization diversity RF/microwave earth or satellite communication and measurement systems, radars, etc.

Bandwidth enhancement of coupled‐fed on‐board printed PIFA using bypass radiating strip for eight‐band LTE/WWAN slim mobile phone

“…The simulation SAR model with the proposed antenna held by the user's hand and attached to the user's head is shown in Figure 9. Notice that the proposed antenna is mounted at the bottom of the mobile phone [7,12,20,23] for its promising practical applications with decreased SAR values. The distance between the palm center and main ground plane of the mobile phone is set to 33 mm [31].…”

“…Promising on-board printed antennas with a small printed area on the system circuit board for WWAN (wireless wide area network) operation covering the GSM850/900 bands (824-960 MHz) and GSM1800/1900/UMTS bands (1710-2170 MHz) in the mobile phone have also been reported very recently [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. These on-board printed WWAN antennas include using the k/8 printed PIFA (planar inverted-F antennas) [6], k/8 printed monopole [11,12], k/4 printed slot [15][16][17][18], and k/4 printed loop [22][23][24] to achieve reduced antenna size yet wide operating bands.…”

Small‐size coupled‐fed shorted T‐monopole for internal WWAN antenna in the thin‐profile mobile phone

“…Owing to the small printed size (15 Â 26 mm 2 ) for the antenna, it can be arranged to locate on one corner of the no-ground portion at the bottom position of the system circuit board, saving a large portion of the no-ground portion to accommodate other associated electronic elements in the mobile phone. Note that by arranging the printed internal antenna at the bottom position of the mobile phone can result in decreased radiated wave energy absorption by the user's head tissue [9,13,[16][17][18], resulting in much lower SAR values obtained. This arrangement of the internal WWAN antenna in the mobile phone is hence attractive and has been applied in practical applications.…”

“…Different from the conventional patch PIFAs [1][2][3][4][5], the wideband internal antennas can be obtained by removing the ground plane below the radiating portion of the antenna [6,8] or printing the antenna directly on the no-ground portion of the system circuit board of the mobile phone [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The antennas in the former case [6,8] still show a 3D structure and their fabrication cannot be simplified.…”

“…For the latter case, they generally show no thickness above the circuit board of the mobile phone and can be easily fabricated at low cost, making the internal printed antennas very good candidates for thin-profile mobile phone applications. The reported promising internal printed WWAN antennas include the use of printed monopole elements [9,10], the printed PIFA or shorted monopole elements [11][12][13], the printed loop elements [14][15][16][17][18], the printed slot or monopole slot elements [19][20][21][22][23], and so on. Most of the reported internal printed WWAN antennas cover all the five WWAN bands of GSM850/900/1800/1900/UMTS.…”