Low Profile Multi-Slot Loaded Antenna With Enhanced Gain-to-Volume Ratio and Efficiency

Abstract

A printed circuit board (PCB) implementable multi-slot loaded antenna with a low-profile air-gapped structure for both gain and efficiency enhancement is proposed. The proposed planar antenna is configured by the upper substrate with a radiation patch separated from the lower substrate consisting of a pair of matching pads and a ground plane by the air-gap. The radiation patch on the upper substrate is loaded by two rectangular slots and a single narrow slot with a symmetrically placed feed point and a shorting pin. The narrow slot on the center of the radiation patch with the shorting pin improves both gain and radiation efficiency. The pair of two additional rectangular slots increase the gain while maintaining the required air-gap very low. Further, the symmetric matching pads are integrated along the feed and shorting vias to improve the realized antenna gain for the whole operation band. As a result, the proposed structure obtains a high gain-to-volume ratio as well as the enhanced efficiency. The proposed structure was fabricated at 5.9 GHz with the overall volume of 1.08 λ0 x 1.08 λ0 x 0.05 λ0 (55 mm x 55 mm x 2.7 mm) including the whole ground plane. The measured antenna gain was 9.4 dBi at 5.9 GHz verifying the high realized gain-to-volume ratio. Also, the measured half power beamwidths in E and H planes were about 72˚ and 74˚, respectively. Lastly, the measured 10-dB impedance bandwidth of the proposed structure showed approximately 5.5 %.INDEX TERMS Antenna gain enhancement, high efficiency antenna, low-profile antenna, slot-loaded antenna, shorted patch antenna

Efficiency enhancement techniques of microwave and millimeter‐wave antennas for 5G communication: A survey

“…The antenna's overall efficiency is 98%, with 5.5% impedance bandwidth and 9.2 dB gain. The minimum cross polarization discrimination is around 20 dB 10 …”

“…Paper 10 proposes an efficiency enhancement approach with a high gain‐to‐volume ratio. As illustrated in Figure 11, the proposed geometry consists of a slotted patch on the top substrate, a matching layer on the middle air substrate, and a ground plane with an air gap on the lower layer.…”

“…The minimum cross polarization discrimination is around 20 dB. 10 Table 7 consists of results of discussed antennas with recessed ground or recessed substrate and details about all performance parameters. Recessed ground and recessed substrate approaches concurrently increase antenna bandwidth, efficiency, and gain, which is essential for 5G and future generation communication.…”

“…Low loss, low permittivity dielectric substrates can be used to reduce dielectric losses and power dissipation losses in substrates, however they are expensive and increase the size of the antenna owing to an increase in the value of the guided wavelength. 1,2,8,9 Dielectric losses or substrate losses can be reduced using several other ways such as removing a section of the substrate, 8 constructing an air gap, 10 air filled metallic cavity, 11 substrate insensitive antennas, [12][13][14] Fabry-Perot antennas, [15][16][17] and employing artificial materials in substrate. 18 Conductor losses or ohmic losses can be decreased by employing several stacked laminated conductors for patch instead of a single conductor, [19][20][21] dielectric material for patch instead of metallic patches, 22 dense dielectric patch, 23 and so on.…”

“…56 When dielectric constant is decreased, the effective length and width of antenna increases and total aperture area increases, which upsurges the overall gain of the antenna and enhances the fringing field of the antenna, also bandwidth of the antenna improves. Performance of antenna is enhanced by selecting substrate of low dielectric constant, but the size of the antenna is also increasing because the length and width of microstrip patch is inversely proportional to dielectric constant of the substrate (can be seen from Equations (10) and ( 12)), and these low loss substrates are very costly. 4 The length (L) and width (W) of rectangular microstrip patch can be calculated using following Equations ( 10) and (11), respectively.…”