Leakage from higher modes on microstrip line with application to antennas

Abstract

Some confusion in the literature is clarified regarding the properties of microstrip‐line higher modes in the neighborhood of cutoff. It is shown that those modes become leaky in that range; with the aid of the steepest‐descent plane, one finds that the continuous spectrum can be characterized in a highly convergent manner by essentially a single leaky mode. The leakage occurs in two forms: a surface wave and a space wave. For structures without a top cover, it is found that almost all of the leakage is in the form of a space wave, so that an efficient leaky‐wave antenna of particularly simple configuration may be designed that consists of just a length of uniform microstrip line fed in its first higher mode. An accurate leaky‐wave analysis is developed that explains quantitatively the performance features and the limitations of this class of antennas.

Travelling Planar Wave Antenna for Wireless Communications

“…The radiation mechanism of the higher order mode on microstrip LWAs is attributed to a traveling wave instead of the standing wave as in patch antennas [13,20].…”

“…Therefore, if we know the begin width and the end width of the antenna, from the curves of normalized phase and attenuation constant at fixed frequency, we can determine the beam radiation range from (16), and the main beam angle through (20). ) [25].…”

Leaky and surface waves in multilayered laterally‐shielded microstrip transmission lines

“…In addition to these iterative strategies, graphical procedures to approximately locate the complex leaky wave poles have also been derived [9]. Also, although many investigations have been conducted for basic printed lines [1][2][3][4][5][6][7][8][9][10], the same is not generally true for laterally shielded configurations. In all previous works, the infinite nature of the dielectric substrates yields to continuous wavenumbers in the spectral domain.…”

“…The leaky modes excited in open microstrip-like structures have been studied in the past by many researchers [1][2][3][4][5][6][7][8][9][10][11][12][13]. This radiation mechanism can be undesirable for printed-circuit applications, since it can cause interference and thus deteriorate the system performance.…”

“…Circularly polarized microstrip antennas that have been studied usually have a square or circular ground plane, and the ground plane is symmetrically centered below the microstrip patch [1][2][3]. However, for practical applications, the antenna may be required to be mounted on a ground plane of non-square or non-circular shape.…”