We investigate the characteristics of a wideband and high‐gain cavity‐backed slot antenna in terms of the reflection coefficients, radiation patterns, and gain. A cavity‐backed slot antenna structure includes baffles, reflectors, and thick ground planes. The measured gain and bandwidth of a 10‐dB return loss in a cavity‐backed 2 × 2 array slot antenna with h1=2 mm, d = 2 mm are 15.5 dBi and nearly 27% respectively, at 42 GHz. Baffles and reflectors are used to increase antenna gain, thus reducing the coupling among the slots on the thick ground plane.

Mcrowave ab601Joi ng pqmties of the mtoichi&c ampmds of Ni-Zn fesritt~ with excess F& are investigated Tmidal corrpacts of &ZmsO)1~(Fe2oj)~ spiws are msmd by the mvmtiional &c mccming techiqe ?he magwtic and dieldc constant are greatly depRtdent upcn the amxlnt of excess F a (y) 0). BcQh the real a d hgilliny mrponents of-bid@ decrease as the ewcess F a imeases On the other hand the dielecbic mtant inrreasg with the increase of exfess F & 'Re oombined effect of high diektric amstant and iow pmmbiity &ts in a l o w e r h n c y inpdam mtching. Tbe plate thickness at the m-reflectim fnqmy is predided using the m t d iwdam-matching relaticn&ip behYeen wavelength and rmterial pamr&m.

A compact aperture coupled patch type microstrip‐to‐waveguide transition at V‐band is proposed and fabricated using low‐temperature cofired ceramic process. It uses the aperture coupled microstrip feed and the parasitic patch antenna radiating into the waveguide to improve the insertion loss and the bandwidth. As a result of experiments, low‐transmission loss and high‐return loss are realized at the design frequency of 60 GHz. For a 10‐dB return loss, a relative bandwidth of 13.8% is obtained for a fabricated back‐to‐back transition. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 433–435, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24941

Analytic modeling and computational simulation for the protection of DTV from cognitive radio interference are performed. Protection is achieved by using the protection ratio, which is derived through system modeling and its analysis. On the frequency coordination between digital TV and cognitive radio, an analysis in a co‐channel environment, in a rural area in Korea, is performed.

In this paper, we propose a small broadband antenna for mobile device. The proposed antenna consists of a printed rectangular monopole antenna and a parastic element connected to ground using narrow meander line and it is designed on a FR-4 substrate that has a thickness of 0.8 mm and a dielectric constant of 4.4. The FR-4 substrate's size is 50 mm×90 mm comparable to the real mobile device. The fabricated antenna's size is 12.5 mm×10.5 mm×0.8 mm and the measurement shows -10 dB return loss bandwidth of 2,200∼6,000 MHz and gains of 2.86∼4.01 dBi. Accordingly, the proposed antenna can support mobile device for WiBro(2,300∼2,380 MHz), WLAN(IEEE 802.11b/g/n: 2,400∼2,480 MHz, IEEE 802.11a: 5,150∼5,825 MHz), and mobile WiMAX(IEEE 802.16e : 2,500∼2,690 MHz, 3,400 ∼3,600 MHz) service bands.