change vary significantly. To attain good impedance matching about 698–960 MHz and 1710–2170 MHz, in this study the slot gap is optimized to be G ¼ 12 mm. A parameter study has been performed to evaluate the effects of the strip lengths on return loss. As shown in Figure 4(a), by increasing the length of the L 1 strip, the resonant fre- quencies in the lower and upper bands decrease. However, the medium bands do not change significantly. The L 2 –L 4 strips perform similarly as the L 1 strip to enhance the bandwidths to- gether with the L 1 strip. Figure 4(b) shows that the M 1 strip works for the medium and upper bands but not the lower one. By increasing the M 1 strip length, the resonant frequencies in the upper bands reduce. Likewise, the M 2 –M 8 strips function with the M 1 strip to improve the medium and upper bands. For tuning only the upper bands, one may vary the H 1 strip as shown in Figure 4(c). Likewise, the H2 strip radiate in the upper bands too. A spherical near-field antenna measurement anechoic cham- ber (NSI) was used to measure antenna radiation properties. Accurate antenna radiation efficiencies and 3D patterns from 500 MHz to 18 GHz can be obtained with this chamber. Figures 5(a)–5(c) exhibit the measured far-field radiation patterns in the xy, yz, and xz planes defined in Figure 1(a) for three frequencies at 800, 1900, and 2600 MHz, respectively. Fairly omnidirec- tional patterns in those three frequencies are obtained. Also, measured antenna average gains and radiation efficiencies are plotted in Figure 6. For the LTE700 and GSM850/900 bands, the antenna average gain varies from 2.41 to 0.56 dBi and the radiation efficiency is large than 51%, as shown in Figure 6(a). Results in the other bands are given in Figure 6(b). The antenna average gains and radiation efficiencies are from 2.86 to 0.74 dBi and 53–84% for the DCS/PCS/UMTS band and LTE2500 band, respectively. Therefore, good antenna efficien- cies are obtained for the LTE700/2500, and WWAN operations with the compact antenna embedded in the ultra-thin laptop computer. In Table 1, comparisons of the proposed antenna with those reported in Refs. 1–7 on antenna dimensions and band- widths are given. Our antenna is both compact and wideband for suitably integration into the ultra-thin laptop computer. 4. CONCLUSIONS A compact slot inverted-F antenna for the LTE and WWAN operations has been carefully presented and analyzed. This antenna is flexible in tuning bandwidths and capable of perform- ing good omnidirectional coverage and high radiation efficien- cies throughout all the operating bands. Also, compared with previous designs, the proposed antenna with an even more com- pact size is suitable to be integrated within the u laptop com- puter as an internal antenna for the LTE700, GSM850/900, DCS/PCS/UMTS, and LTE2500 applications. REFERENCES 1. C.-H. Kuo, K.-L. Wong, and F.-S. Chang, Internal GSM/DCS dual- band open-loop antenna for laptop application, Microwave Opt Technol Lett 49 (2007), 680–684. 2. X. Wang, W. Chen, and Z. Feng, Multiband antenna with parasitic branches for laptop applications, Electron Lett 43 (2007), 1012–1013. 3. Y.-W. Chi and K.-L. Wong, Compact multiband folded loop chip antenna for small-size mobile phone, IEEE Trans Antennas Propag 56 (2008), 3797–3803. 4. K.-L. Wong and L.-C. Lee, Multiband printed monopole slot antenna for WWAN operation in the laptop computer, IEEE Trans Antennas Propag 57 (2009), 324–330. 5. K.-L. Wong, and F.-H. Chu, Internal planar WWAN laptop com- puter antenna using monopole slot elements, Microwave Opt Tech- nol Lett 51 (2009), 1274–1279. 6. C.T.P. Song, Z.-H. Hu, J. Kelly, P.S. Hall, and P. Gardner, Wide tunable dual-band reconfigurable antenna, Electron Lett 45 (2009), 1109–1110. 7. C.-W. Chiu and Y-J Chi, Planar hexa-band inverted-F antenna for portable device applications, IEEE Antennas Wirel Propag Lett 8 (2009), 1099–1102. V C 2011 Wiley Periodicals, Inc. INDIRECT EVALUATION OF RADIATED EMISSIONS FROM A BENT SIGNAL LINE ON A PRINTED CIRCUIT BOARD WITH TWO ATTACHED CABLES Dong-yeon Kim, 1 Jae W. Lee, 1 Choon Sik Cho, 1 Haeng S. Lee, 2 and Yeon-Choon Chung 3 1 School of Electronics, Telecommunication and Computer Engineering, Korea Aerospace University, 200-1, Hwajeon-dong, Deogyang-gu, Goyang, Gyeonggi-do 412-791, Korea; Corresponding author: jwlee1@kau.ac.kr 2 Department of Electronic Engineering, Sogang University, 1 Shinsu-dong, Mapo-gu, Seoul, Korea 3 Department of Information and Communication, Seokyeong University, 16-1, Jungneung-dong, Sungbuk-gu, Seoul 136-704, Korea Received 19 October 2010 ABSTRACT: In this article, the radiated emissions mechanism and the variation of radiated emissions level have been analyzed and investigated, respectively, according to the ratio of the horizontal to vertical traces in a bent signal line when a bent signal line on a printed circuit board (PCB) with two attached cables is used. Though many TABLE 1 Comparisons of the Antenna Size and Bandwidth Published Literature Bandwidth Comparison Antenna Size Comparison (Proposed/Literature) (%) LTE700/GSM850/GSM900 Bands (%) DCS/PCS/UMTS/LTE2500 Bands (%) [1] Kuo et al. 889974 MHz (9.1) 16681897 MHz (12.8) 17.2 [2] Wang et al. 800960 MHz (18.1) 16702120 MHz (23.7) 18 [3] Chi et al 890960 MHz (7.6) 17102250 MHz (27.3) 54.3 [4] Wong et al 785985 MHz (22.6) 16302300 MHz (34.1) 94.2 [5] Wong et al 820990 MHz (18.8) 17002200 MHz (25.6) 90.5 [6] Song et al. 8001000 MHz (22.2) 13002670 MHz (69) 38.8 [7] Chiu et al. 880960 MHz (8.7) 17002700 MHz (45.5) 64.6 Proposed 659973 MHz (38.5) 16892179 MHz (25.3) 100 24492779 MHz (12.6) 1832 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 53, No. 8, August 2011 DOI 10.1002/mop