No abstract

Transparent material has been widely used in product design and has seen a large increase in its use. In this paper, a kind of aesthetically decorative 5 GHz Wi-Fi dielectric resonator antenna (DRA) of aluminum oxynitride (AlON) transparent ceramic has been designed. High-quality-factor AlON transparent dielectric ceramics were fabricated by presintering at 1780 °C and further cold isostatic pressing (CIP) under a 200 MPa argon atmosphere. For a 9.0 mm thick specimen, the in-line light transmittance reached 83%. Optimum dielectric constant (εr = 9.32), quality factor (Q f = 47 960) and temperature coefficient (TCF = −51.7 ppm/°C) was achieved in the AlON transparent ceramic by cold isostatic pressing. As a result, the proposed aesthetically decorative DRA can achieve an impedance bandwidth of 32% (4.48–6.19 GHz), a high radiation efficiency of 85%, and a low cross-polarization discrimination (XPD) of −30 dB. To achieve a broad bandwidth, the proposed antenna was excited in its dominant TE111 x mode and higher-order TE113 x mode. The proposed antenna is thus an excellent candidate for an indoor decoration Wi-Fi antenna.

Herein, a series of microwave dielectric materials in the Na2O-Bi2O3-MoO3 ternary system were studied via phase identification, microstructure characterization, spectral analysis and microwave dielectric properties test, such as Na2MoO4, Na6Mo10O33,...

A series of low‐temperature firing ceramics with scheelite structure, [Ca0.55(Sm1‐xBix)0.3]MoO4 (x = 0.2–0.95), were prepared via solid‐state reaction. The sintering temperature ranges from 660 to 760°C. A standard tetragonal scheelite phase was formed without secondary phase. When the x value was 0.95, the temperature coefficient of resonant frequency (τf) moved to a near zero value (−2.1 ppm/°C) with a dielectric constant 13.7 and the quality factor (Qf) of 33 200 GHz. The Raman spectra shows that the more vibration modes appeared with x value, which is due to the increasing of Bi concentration and results in increase in permittivities and decrease in Qf values. The classical harmonic oscillator model is used in the infrared spectra and extrapolate to the microwave range. The [Ca0.55(Sm1‐xBix)0.3]MoO4 ceramics show high‐performance microwave dielectric properties at low‐sintering temperature.

Fifth-generation mobile communication systems provide a huge market for microwave dielectric materials, especially in the manufacture of dielectric resonators, filters, substrates, and antennas. Herein, an excellent performance microwave dielectric ceramic x(NaBi)0.5MoO4–(1–x)­MoO3 (0.2 ≤ x ≤ 0.9, abbreviated as xNBM–(1–x)­MO sintered below 660 °C with two coexisting phases is prepared via a solid solution reaction. With the increasing x value, the sintering temperature rises from 600 to 640 °C. The dielectric properties have a series of changes with increasing permittivity (10.3–28.1), decreasing Q f value (12,080 to 8600 GHz), and increasing τ f value (−27.1 to +21.2 ppm/°C). Typically, at the ultralow temperature of 630 °C, the 0.8NBM–0.2MO ceramic exhibits great microwave performance with εr ∼ 24.4, Q f ∼ 9030 GHz (7.7 GHz), and a near-zero τ f ∼ 7.2 ppm/°C. A prototype dielectric resonator antenna is manufactured using a 0.8NBM–0.2MO ceramic. A high-impedance bandwidth ∼360 MHz can be obtained in the antenna at 7.74 GHz with −10 dB transmission loss (S 11). Furthermore, the chemical compatibility with Al powder indicates that the xNBM–(1–x)­MO composite ceramics may be promising microwave materials for applications in ultralow-temperature co-fired ceramic technology.