Proposed is the design of a rear on-glass antenna for a commercial saloon/sedan. It adapts the mesh-grid structure and proposes the optimum design parameters to maximise matching bandwidth and improve the average vertical gain for the entire FM radio band. The detailed design parameters are determined using the Pareto genetic algorithm with an EM simulation tool. The optimised rear on-glass antenna is built and installed on a commercial saloon/sedan. The measurement results show a half-power matching bandwidth (VSWR , 5.8) of about 25%, an average bore-sight gain of about 25.43 dBi in the entire FM band, and an average gain of about 23.29 dBi along the azimuth direction.Introduction: To improve the durability and appearance and to reduce the wind noise of the pole-type FM antenna, an internal on-glass antenna that is printed on the rear or quarter window has been widely adopted by new types of saloon/sedan models. However, because on-glass antennas are etched directly on the lossy dielectric material of the glass and the antenna's conducting stripline offers only low conductivity to function as defroster lines, antenna performance, including matching bandwidth and radiation gain, is diminished [1]. Therefore, various techniques such as adding vertical lines to improve the vertical radiation gain or inserting additional tuning bars to improve the bandwidth characteristics have been introduced [2]. Nevertheless, the radiation characteristics of on-glass antennas with those techniques cannot reach the desired performance when compared to a conventional pole-type antenna.In this Letter, we propose a novel rear-window antenna using virtual mesh-grid vertical segments between horizontal defroster lines. This mesh-grid shape is known to provide a broad matching bandwidth by more uniformly distributing the currents on the antenna, and the complete shape is determined by connecting or disconnecting each vertical grid line. We optimise grid connections and disconnections using the Pareto genetic algorithm incorporation with the full-wave EM simulation tool (FEKO of EM Software and Systems) [3,4]. To achieve multiple design goals of broad matching bandwidth with high vertical gain, we used multi-objective cost functions in our GA approach. In the EM simulation, we include the entire vehicle to estimate the antenna performance more accurately because the total length of the vehicle is in the order of the wavelength of the FM band. To verify the optimised result, the optimum design is printed on the rear window of a commercial vehicle, and its antenna performances, such as VSWR, radiation pattern, and antenna gain, are measured. The optimised design showed a half-power matching bandwidth of about 25% (VSWR , 5.8), an average bore-sight gain of about 25.43 dBi for the entire FM band, and an average gain of about 23.29 dBi along the azimuth direction.

In this article, we propose the design of a rear on‐glass antenna for a commercial sedan. We focus on optimizing the vertical lines of the antenna and propose the optimum design parameters to maximize the matching bandwidth and improve the average vertical gain for the entire FM radio band. The detailed design parameters are determined using the Pareto genetic algorithm with an EM simulation tool. The optimized rear on‐glass antenna was built and installed on a commercial sedan. The measurement results showed a matching bandwidth of about 15%, an average bore‐sight gain of about −2.86 dBi in the entire FM band, and an average gain of about −14 dBi along the azimuth direction. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1445–1449, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25184

isolations greater that 35 dB and 49 dB, respectively, have been achieved in simulation. Simulated VSWR at all ports are better than 2.0. The measured conversion loss is 6-8 dB for þ10 dBm LO power in whole RF band. The measured LO-IF and LO-RF isolations are greater than 40 dB and 45 dB, respectively. Simulated and measured conversion losses are shown in Figure 4. The agreement of the simulated and measured results is fairly good. Table 2 summarizes the simulated and measured results. The fabricated prototype mixer shown in Figure 5, used for demonstration of the design, was precision machined from aluminum and measures 30 Â 25 Â 22 mm 3 . CONCLUSIONSA broadband single balanced waveguide mixer at K-band has been developed. The mixer configuration is of crossbar type and is implemented in suspended stripline circuit integrated with RF and LO waveguides. The mixer has wide IF bandwidth with fixed LO frequency. The Mixer has been simulated, fabricated, and measured. Simulation and measured results agrees well. The measured conversion loss across the whole band is 6-8 dB, and LO-IF and LO-RF port isolations are greater than 40 dB and 45 dB, respectively. This mixer design approach can also be applied to design broadband mixer at higher frequency bands. This mixer will be used in broadband communication systems. ACKNOWLEDGMENTS