How far apart do repeater antennas need to be?
Relating to the distance between antennas. If UHF antennas are closer than 2 wavelengths [4 feet] apart horizontal, the radiation patterns on both antennas will be distorted to the point coverage will be affected. When space is available, more the 5 feet is best.
How much should I separate between antennas?
Here is the rule: The horizontal distance between antennas should be greater than 1/4 of its wavelength (absolute minimum separation), but it should not be located at the exact multiples of its wavelength (maybe avoid the first 3-4 multiples).
How do you measure isolation between two antennas?
Isolation between a GPS and WIFI antenna that are near each other will be on the order of 20-30 dB, with higher values being preferred. The method of measuring isolation is typically done by connecting both antennas to a Vector Network Analyzer, and measuring S12 (the transmission coefficient).
Can you put 2 antennas next to each other?
Placing two antennas within ~1/2 wavelength of each other will cause them to inductively couple – effectively connecting themselves to each other. This results in detuning both antennas, as well as the high power Tx RF getting routed back down the other antenna, possibly damaging the receiver.
Can I use a splitter to combine two antennas?
Yes you can. I have two antennas hooked to mine using a splitter. Like the others said, you have to make sure that both cables from the splitter to the antennas are exactly the same length.
What is the minimum desirable antenna separation?
As a general rule, the inside antenna and the outside antennas need 20 feet vertical OR 50 feet horizontal separation. If those distances are not feasible for your application, it can be achieved by doing a combination of the two (E.g, 10 feet vertical AND 30 feet horizontal).
What is isolation in MIMO antenna?
In the MIMO system, two or more antennas are used on both the transmitter and receiver sides. A critical point is to arrange compact antenna elements without impairing antenna performance and system requirements. To do that, mutual coupling or isolation between adjacent antennas is a key factor.
What is isolation parameter in antenna?
Antenna isolation is a measure of how easily one antenna will pick up radiation from another antenna, which is quantified in terms of S12 between the two antenna elements. Typical isolation goals are set to at least +20 dB, depending on the product, and isolation can be measured with a vector network analyzer.
What is the difference between a splitter and a combiner?
The difference is that a splitter takes in one signal and makes two out, while a diplexer or combiner takes in two signals and makes one out. Splitters are commonly used for adding a second television to an existing cable. With a satellite or cable system, a splitter could be used to add TV to a separate room.
How much separation does a VHF antenna need?
Based on industry standard isolation charts, spacing two VHF antennas 3m apart vertically will provide approximately 35 dB of isolation while 3m of horizontal spacing will provide less than 20 dB.
How to calculate the isolation of two antennas?
The Friis formula can be used to calculate isolation for any relative position and orientation of two antennas. If the antennas are located and oriented such that they are in the sidelobe region of each other, the peak gain level in the sidelobe regions can be used. Isolation = 22 + 20 log(r/ λ) – (Gt,SL + Gr,SL)
What does isolation mean in a repeater system?
Isolation is a cumulative number, provided by the collective hardware that comprises a repeater. Individual units can have good and bad features, some of which can enhance the total, some are neutral, some can degrade the total.
Why do you need a directional antenna for a cellular repeater?
Directionality is also important in reducing the possibility of feedback/oscillation (analogous to ‘microphone squeal’) in the cellular repeater. One should attach a directional outside antenna on the side of the building facing the base station.