As today’s communication devices are becoming smaller in size, they need antennas also of small size which are capable of providing higher performance. Modern telecommunication systems need antennas with wider bandwidth, multiband support, low cost and conventionally smaller design dimensions for commercial as well as military applications. This ever increasing demand of small, multiband antenn...

We present a review of several types of microwave antennas made of metamaterials, including the resonant electrically small antennas, metamaterial-substrate patch antennas, metamaterial flat-lens antennas, and Luneburg lens antennas. In particular, we propose a new type of conformal antennas using anisotropic zero-index metamaterials, which have high gains and low sidelobes. Numerical simulatio...

Electrically small antennas are of interest in a variety of applications, particularly where the antennas must be unobtrusive. The performance properties considered in the design of small antennas typically include impedance, radiation efficiency, pattern shape, polarization and particularly operating bandwidth and quality factor (Q). In this paper, we compare the performance properties of seve...

The bandwidth limitations of resonant, electrically small antennas that fully occupy a spherical volume are well defined by the inverse of the Chu-limit or the lower bound on quality factor. Recently, Gustafsson et al developed lower bounds for the Q of antennas of arbitrary shape. We have previously described antenna designs fully occupying a spherical volume and a cylindrical volume that exhi...

Antennas have traditionally been measured in anechoic chambers. An anechoic chamber is a suitable and necessary reference environment to measure large antennas that are used in a Line-Of-Sight (LOS) environment, but it is an unsuitable environment to measure devices with small antennas. Devices with small antennas are normally used in a Non-LOS environment, which is typically characterised by a...

1 Abstract—The paper discusses recent developments and challenges in the design of small omnidirectional circularly-polarized (CP) antennas. Although omnidirectional CP coverage is easily achievable using antenna arrays, it is just recently that small and low-cost antennas delivered this functionality. The paper addresses practical design problems for these antennas, not reported in previous pu...

We study the radiation properties of electrically small resonant antennas (ka < 1) composed of electric-field-coupled (ELC) and complementary electric-field-coupled (CELC) resonators and a monopole antenna. We use such parasitic ELC and CELC “metaresonators” to design various electrically small antennas. In particular, monopole-excited and bent-monopole-excited CELC resonator antennas are propo...

In this work, a parametric up-converter amplifier is introduced as wideband impedance-matching network. Chu’s limit restricts the minimum Q-factor of unloaded small antennas. However, practical bandwidth (BW) antennas defined by their loaded Q-factor. By connecting antenna to an with real input impedance that several times greater than radiation resistance antenna, we propose increasing return ...