Two λ/2 dipole array coplanar feed wideband PCB antenna

Microstrip patch antennas are intrinsically narrow bandwidth devices, i.e. less than 10 %. Special techniques are always applied in order to increase their bandwidths. These include complicated wideband balun impedance transformers and parasitic elements. Abdelaziz reported a 10 GHz dual-element microstrip patch antenna design which was printed on a 1.6 mm thick Duriod substrate [1]. The two elements resonate at 9.64 and 10.74 GHz, respectively. Enhanced by two rectangular parasitic patches, the omnidirectional antenna covers 9.3-10.5 GHz, i.e. a bandwidth of 1.2 GHz (12 %). Vasiliadis et al proposed a double-sided printed dipole antenna on Taconic-TLY5 substrate (εr = 2.21) which is fed by a tapered balun [2]. It covers 2.19-3.97 GHz obtaining a bandwidth of 1.78 GHz (60 %) with gains of 2.9 to 5.5 dBi, for a dimension of 50 mm×30 mm×1.6 mm. Lindberg et al presented a dual wideband printed dipole antenna on 0.8 mm thick double-sided 133 mm×70 mm FR-4 PCB which covers 824-960 MHz (15 % bandwidth of 136 MHz with gain <2.0 dBi) and 1.65-2.35 GHz (36 % bandwidth of 700 MHz with gain <2.5 dBi) [3]. The key component of this antenna is a wideband transition from unbalanced microstrip line to balanced coplanar slotline. Pan printed a coplanar waveguide (CPW) collinear array on a 30 cm×3 cm 1.6 mm thick FR-4 substrate [4]. This pseudo-omnidirectional antenna consists of multiple CPW radiating elements resonating at several frequencies. It covers two commonly used wide bands: 750-1050 MHz (33 %) and 1.7-2.9 GHz (54 %).