Otto, Simon; Al-Bassam, Amar; Chen, Zhichao; Rennings, Andreas; Solbach, Klaus; Caloz, Christophe:

Q-Balancing in periodic leaky-wave antennas to mitigate broadside radiation issues

In: 2012 the 7th German Microwave Conference (GeMiC) : 12 - 14 March 2012, Ilmenau, Germany
Ilmenau: Univ. of Technology, Dep. of Electrical Engineering and Information Technology, Inst. for Information Technology, RF & Microwave Research Laboratory (2012), S. 155 - 158
ISBN: 978-3-9812668-4-9, 978-1-4577-2096-3, 978-3-9812668-5-6
Buchaufsatz / Kapitel / Fach: Elektrotechnik
Fakultät für Ingenieurwissenschaften » Elektrotechnik und Informationstechnik » Hochfrequenztechnik
This paper illustrates and applies the recently established
Q-balancing condition in frequency-scanning periodic
leaky-wave antennas (LWAs) for achieving a frequency independent leakage factor and input impedance. The unit cells of such LWAs can be modeled by an equivalent two-port network comprising two independent circuit elements, a series resonator and a shunt resonator, which are characterized by their resonance frequencies ( fse, fsh) and quality factors (Qse,Qsh), where the quality factors correspond to the reactive energies stored over the radiated and dissipated powers in each respective resonator.
The Q-balancing condition consists in achieving equal quality factors for the series and the shunt resonator: Qse = Qsh. Here, we propose two general concepts –the resistive loading concept– and –the asymmetry concept– to design LWAs based on the Q-balancing criteria. Furthermore, we apply the aforementioned concepts to the specific example of a series-fed patch array (SFPA) LWA to obtain a frequency independent input impedance and hence a constant gain for the LWA radiation through broadside.