This paper proposes a dual-band dual-rectangular-loop circular polarization antenna for Global Navigation Satellite Systems (GNSSs). The proposed antenna combines two large outer rectangular loops with two small inner loops. Each large outer loop is connected to its corresponding small inner rectangular loop. Each loop has gaps located symmetrically with respect to a feed point to produce Right Handed Circular Polarization (RHCP). The gap position and the shape of the rectangular loops are very important to adjust both the impedance matching and circular polarization characteristics. The proposed antenna offers dual-band Voltage Standing Wave Ratio (VSWR) and Axial Ratio (AR) frequency characteristics that include the L1 (1575.42 MHz) and L2 (1227.60 MHz) bands. The antenna gains exceed 8.7 dBi. Broad AR elevation patterns are obtained. These antenna characteristics are well suited to precise positioning.

This paper proposes a new small multiband printed antenna for wireless telecommunications modules that can realize Machine-to-Machine applications. We reconfigure our previous antenna to cover the 700MHz, 800MHz, and 900MHz bands, and add two new elements (second strips) to cover the 2GHz band. The new antenna achieves operation in quad-bands: 700MHz, 800MHz, 900MHz, and 2GHz. Frequency characteristics are analyzed using electromagnetic-simulation software based on the method of moments, and the validity of the numerical results is shown based on measured Voltage Standing Wave Ratio (VSWR) characteristics and the radiation patterns of a prototype antenna. The proposed antenna is compact with a VSWR bandwidth (≤2) of 27.5% in bands including 700MHz, 800MHz, and 900MHz, and a VSWR bandwidth (≤2) of 10.6% in the band including 2GHz. We clarify that the operating mechanism in the 2GHz band is equivalent to that of a one wavelength folded offset fed dipole antenna comprising a monopole element and second strips, and that the operating frequency in the 2GHz band can be determined by the path length from the tip of the monopole element to the tip of the second strip via a feeding point.

A small broadband omni-directional printed antenna comprising symmetrically arranged trapezoid elements is investigated for broadband Voltage Standing Wave Ratio (VSWR) and low center frequency characteristics. Two symmetrical trapezoid elements are printed on the bottom side of the substrate and are connected to a small ground plane printed on the same side over two strips. The trapezoid elements and the strips are excited in an electromagnetically coupled manner by the monopole element set between the trapezoid elements. Two resonance characteristics arise because the resonance part changes depending on the frequency, and a broad bandwidth becomes possible. The center frequency can be lowered by changing the shapes of the trapezoid elements. The monopole element length is a very important parameter for impedance matching. The space between the monopole element and the trapezoid elements is an important parameter for the optimization of two resonance characteristics. The proposed antenna is shown to achieve a VSWR bandwidth (≤2) of 28.9%, a low profile, and omni-directional pattern features. The measured and numerical results are in good agreement.