User's Manual

LRU User Manual Antennas
1-9
Antennas
The LRU is used as a point-to-point radio relay. For a stationary relay,
directional antennas are used, allowing maximum performance and
protection from interference. Where one of the two LRUs involved in a
radio relay is subject to roving (Marine, Shalow-water operation, etc.)
omni-directional antennas are more suitable.
Directional antenna
Below are the specifications of a wide-band, 7-element Yagi antenna
available from SERCEL.
This directional antenna can be used either horizontally or vertically.
A 50-ohm impedance coax cable should be used to connect the antenna
to the LRU. To increase the system performance, a low-attenuation,
double-shield coax cable is recommended.
Prior to using the antenna, especially after assembly, a VSWR check
should be done, including the coax cable. The maximum VSWR within
the bandwidth of interest should be less than 1.5:1 to work in good
conditions.
• Specifications
• Type: Wideband 7-Element Yagi
(Sercel P/N: 07-820070-001).
• Frequency: 215 to 240 MHz.
• Power Gain: 10.5 dBi, Center frequency.
• VSWR: 1.6:1 Max.
1.3:1 Center frequency.
• Front-to-back Ratio: 20.45 dB, Center frequency
• 3-dB beamwidth: E = 48 degrees.
H = 57 degrees