An omnidirectional antenna (also called a non-directional antenna) radiates and receive signals equally well in all directions. Many wireless network applications use omnidirectional antennas as transmitters as the radiated signal emits the same strength in all directions, making it easy for computers all across the building to connect to the network. Onmidirectional Antennas are available in several designs.
The so called "rubber duck" is a small, rubber dipole omnidirectional antenna, and is the default antenna for most wireless network access points and routers. The rubber duck has a compact build, and the rubber or plastic sheathing allows flexibility. Early versions of this antenna used to be sheathed in rubber, but more recent variations have a plastic sheath. Most rubber duck antennas that are used for wireless access points and routers have a gain of between 2 and 2.2 decibel isotropic. Some people place a reflector behind their rubber ducky antenna, to focus the transmitted signal in a certain direction (making it more directional). Using a reflector decreases noise and enhances privacy by ensuring that the signal only goes where you want it to.
The spider omnidirectional antenna is a small antenna with a simple design. The spider consists of a standard N-type chassis mount connector, with short lengths of stiff fencing wire soldered into each corner hole. The spider has a gain of up to three decibels isotropic.
Ceiling Mount Omnidirectional Antennas
Ceiling mount omnidirectional antennas come in different designs, with the purpose of a discreet design serving an indoor area. As the name implies, ceiling mount antennas are mounted against the ceiling, and are often shape like lights. Ceiling mount antennas are often used in so-called "Wi-Fi hotspots," as the antennas support a radiation pattern that is low in vertical beamwidth, but offers a 3.5 decibel isotropic gain to the horizon. This means that the antenna covers a greater floor space than the rubber-duck design.
Outdoor Omni-directional Antennas
Outdoor omni antennas are often called "GP antennas" and provide a 360 degree horizontal coverage. Vertical coverage for outdoor omnidirectional antennas is typically much narrower than those of directional antennas. Outdoor omnidirectional antennas are thus more suitable for areas where receivers are roughly at the same height. Outdoor omnidirectional antennas are typically water and weatherproofed and built to have a higher gain (up to 12 decibel isotropic) to cover greater distances than indoor antennas.