Antenna Systems
Our antenna systems are categorized as fixed and portable. All fixed antennas are located on an antenna farm at our observatory and are described on this page. They are used with the fixed receiver installations described here. The portable antennas generally are whip antennas of varying lengths and configurations used with ELF and VLF receivers. Click here for a description of our portable antennas and click here for a description of the receivers used with them.
Antenna Farm
The antenna farm includes a variety of technologies:
- Active Crossed-Dipole Antenna (LWA Antenna, 5 ~ 90 MHz)
- Active Crossed-Dipole Antenna (MWA Antenna, 80 ~ 300 MHz)
- Active loop antenna (150 kHz ~ 30 MHz)
- Active whip antenna (100 kHz ~ 30 MHz)
- Beverage antenna (~100 kHz ~ 30 MHz)
- Discone antenna (~100 MHz ~ 1 GHZ)
- Large Octagon Loop antenna (3 kHz ~ 150 kHz)
- HF log periodic antenna (18 ~ 32 MHz)
- Collinear dipole antenna ADS-B (L-band)
- Collinear dipole antenna Marine AIS (160 MHz)
- VHF/UHF log periodic antenna (50 ~ 1300 MHz)
- VHF/UHF log periodic antenna (144 ~ 500 MHz)
- Long-wire antenna (200 kHz ~ 30 MHz)
- Yagi antenna (20 ~ 21 MHz)
The transmission lines from each antenna are fed to a central location where the shields are bonded to earth ground at a grounding block.
All antenna transmission lines pass through a grounded protector assembly before connection to a receiver. The grounding and protection bar is made from a 1/8 in x 12 in copper bar with 90 V lightning arrestors rated from dc to 3 GHz. The assembly is bonded to the earth electrode system by 6 AWG copper wire. Heatshrink tubing is used to protect the connections from rain (not all heatshrinks are completed in the photograph below).
