Multi-Directional Antenna Vs. Directional Antenna

Multi-directional antennas are capable of transmitting and picking up radio frequency signals from several directions; whereas directional antennas only transmit and pick up radio frequency signals from a single direction.

Orientation

Directional antennas have to be aimed in a specific direction in order to receive a radio frequency signal being transmitted from a given direction. Multi-directional antennas, on the other hand, don't have to be so precisely aimed. Multi-directional antennas are designed to pick up radio frequency signals from two, four, and sometimes all directions. An all-directional antenna is referred to as omni-directional.

Use

Directional antennas are useful in eliminating problems with multipath interference. Multipath interference arises when the main radio frequency signal is reflected, as a result of bouncing off certain types of structures, causing the antenna to pick up both the main signal and reflected signals. The reflected signals interfere with the main signal, resulting in reception problems. Because directional antennas only receive signals from one direction, within a very defined bandwidth, reflected signals are not a problem.

Gain

Multi-directional antennas have a much lower signal strength (gain) compared to directional antennas. Antenna gain is the measure of the strength of the antenna's signal output or input. Directional antennas are more powerful than multi-directional antennas.

References

• AntennaWeb: FAQs
• Cisco: Omni Antenna vs. Directional Antenna
• GC Audio: FM Antennas
• WKAR: Digital Television from WKAR