年ITU亚太地区监测业务培训-教材6-.ppt

Presented for Pre-address Definitions associate with antenna HF antenna types VHF and UHF omnidirection types VHF and UHF directional types Antennas for frequencies above 3?000 MHz Definitions associate with antenna HF antenna types VHF and UHF omnidirection types VHF and UHF directional types Antennas for frequencies above 3?000 MHz Definitions associate with antenna HF antenna types VHF and UHF omnidirection types VHF and UHF directional types Antennas for frequencies above 3?000 MHz ●Rotatable horizontally polarized log-periodic antenna -Broadband -Rotatable for different direction -Consistent pattern over the entire frequency range -Typical gain: 12dBi -Suitable for medium and long range skywave -Suitable for short range ground wave ●HF Quadrant antenna -Consist of horizontal bent dipoles -Bent angle different for required horizontal pattern -Cannot cover entire HF band -Dipole is performed as an open multi-wire cage ●Vertically polarized monopole omnidirectional antenna -Broadband -Composed of a biconical cage of wire -Typical gain: 4~5dBi -Suitable for short range ground wave -Suitable for moderate to long range skywave ●Magnetic loop antenna -Very small size -Detects the magnetic field -Can be installed in low height. -Sometimes active -Suitable for monitoring and measurement Definitions associate with antenna HF antenna types VHF and UHF omnidirection types VHF and UHF directional types Antennas for frequencies above 3?000 MHz ●Active Receiving Dipole antenna -Small size -High sensitivity -Wide dynamic range -Wide bandwidth -Typical gain: 5dBi Active receiving dipole antenna Definitions associate with antenna HF antenna types VHF and UHF omnidirection types VHF and