Page 283 - Antennas for Base Stations in Wireless Communications

256 Chapter Seven

TABLE 7.2 Various Types of WLAN Antennas in the Market
Gain, dBi
Antennas 0–6 6–8 8–18 18–30
Single monopole 
Helix (normal mode) 
Single dipole 
Slot 
Log-periodic 
Dipole, slot, patch (arrays)  
Yagi-Uda  
Horn  
Reflector, dish 

patch arrays, Yagi-Uda arrays, log-periodic arrays, helix antennas,
cavity-backed slot antennas, waveguide slot arrays, horn antennas, and
reflector antennas. The beamwidth of these antennas is usually between
20°−60° based on the system requirements. A beamwidth of less than
10° requires additional antenna alignment procedures. Also, an antenna
with a high directivity has a lower probability of encountering unpre-
dictable interferences.
Figure 7.5 shows a 2.4–2.5-GHz P2P antenna array that has a gain of
14 dBi. It uses weatherproof galvanized sheet metal with surface treat-
ment for the ground plane. The single-layered radiators with a feeding
network are cut from a 0.5-mm brass sheet and suspended above the

Frequency 2.4–2.5 GHz
Gain 14 dBi

Return loss >10 dB
Polarization Linear
H-plane
28°
3-dB beamwidth
E-plane
28°
3-dB beamwidth

Connectors N-type

Size 200×200×5 mm
(a) (b)
Figure 7.5 A 14-dBi P2P antenna: (a) photo of antenna, (b) antenna specifications, (c)
schematic diagram, (d) return loss, and (e) radiation patterns at 2.4 GHz (Photo courtesy
of Compex Systems Pte Ltd.)