Low‐profile circularly polarised loop antenna assisted with an effective PMC bandwidth

Abstract

Proposed is an ultra-low-profile loop antenna backed by an electromagnetic bandgap (EBG) surface reflector, where the EBG surface can effectively exhibit the property of a perfect magnetic conductor (PMC) inside a deliberately designed bandwidth. It is shown that, assisted by the effective PMC bandwidth, while the proposed antenna is with a 0.07-λ spacing between the loops and the EBG reflector, its axial ratio (AR) and voltage standing wave ratio (VSWR) performances are significantly improved. Experimental measurements show that the prototype antenna has a 3 dB AR bandwidth of 17% with an input VSWR less than 1.6. The proposed approach can find a wide range of low-profile circularly polarised (CP) antenna applications.

Gain Enhancement of Wideband Circularly Polarized UWB Antenna Using FSS

“…Among them, single‐fed CP antennas are commonly used for their simple structure and ease of manufacturing. Most of these antennas use the coplanar waveguide (CPW) feed (Karamzadeh et al, 2015; Shirazi & Honarvar, 2015), and others use the probe feeding technique (Ding et al, 2017; Li et al, 2013), where the CPW‐fed structures are preferred because of their large bandwidth and low profile (Rezaeieh et al, 2013). Printed antennas have low gain, narrow CP bandwidth, which limits their applications.…”

“…However, artificial intelligence‐based design techniques, such as ant colony and particle swarm optimization have recently been used for designing FSSs (Caso et al, 2010; Zhu et al, 2017). In Li et al (2013), an electromagnetic band gap (EBG) structure was used to realize a FSS reflector used with a CP loop antenna, where the AR and the impedance bandwidth were improved at a price of more complex prototyping, due to the introduction of metallic vias within the EBG structure. To remove this fabrication complexity, Meta‐Surface (MS) or FSS is introduced to improve CP radiation characteristics.…”

Wideband CP slot antenna with backed FSS reflector

“…In recent years, periodic structures such as high-impedance surface (HIS), electromagnetic band gap (EBG) and artificial magnetic conductor (AMC) are being used as a reflector [8][9][10][11] to improve antenna's bandwidth and gain. In [8], a loop antenna backed by an EBG reflector was proposed. Although its impedance bandwidth and AR performances were significantly improved, the 3 dB AR bandwidth was only 17%.…”

“…The AMC plane is also designated as HIS, so it could be used as a reflector to improve the antenna performance too [10,11]. Although the performances of antennas in [8][9][10][11] are greatly enhanced, the AR bandwidths were still <50% which is insufficient for some broadband applications. Another periodic structure such as frequency selective surfaces (FSSs) is also demonstrated to improve LP antenna characteristics recently [12,13].…”

Tri Band CP Slot Antenna Backed with Dual FSS Reflector

“…Both AMC and HIS plane are same, which is used as a wall to reflect the EM waves which will improve antenna performance [10,11]. The antenna performances in [8][9][10][11] aren extraordinarily upgraded, but the BW is less than 50% in which it cannot be used for some broadband. Another self symmetry structure, such as frequency selective surfaces (FSSs) isused in addition shown to improve the characteristics LP antenna [12,13].Howover, FSS was utilized likewise as a reflector in coplanar waveguide-sustained CP antenna [14].However, the radiation patterns of the antenna backed with FSS CP, where beam tilted problem is more lead to heavy problem in the entire band leads to pattern stability.…”