RF Components
Isolators
• They allow RF to flow in one direction.
• They protect the Tx modules from reflections caused by broken antennas or feeder.
• They do not protect equipment from lightning strikes.
• Take care when using these at high power. When they overheat they’ll add resistance to the RF path.
Hybrid Couplers
• It combines the 2 inputs sockets and sends 50% to each of the output sockets.
• On larger IN radio comms jobs a dummy load is added to one of the outputs so half of the power is lost.
• These are rated to 200W but make sure you put an adequate dummy load on the end and add some means of cooling it too.
Directional Couplers
• These are non-equal splitters and allow to put a small amount of RF in a room whist putting the majority somewhere else (-10db out of the secondary output here).
• These can also be used in reverse allowing the placement of multiple Rx antennas
Power Splitter
• These are High power 50/50 splitters that can split High wattage carriers.
• These can also be used in reverse and combine 2 different Rx antenna.
ZAPD-1
• These are the same as a Power Splitter with the exception that they can handle no more than 3W.
• Can be used as a 50/50 split on an Rx antenna.
• These can’t handle as much as a power splitter can so be careful when programming the Tx power.
Dummy Load
• These are put on the end of open connections and absorb RF radiation.
• They are rated as to how much power they can take so keep an eye on the labels.
• These can get very hot so be careful when they’re in use.
Note: You may want to consider using a fan for High Power applications.
Band Pass Filter
• These pass a specific set of frequencies (usually 10-20MHz wide).
• The pass window can be adjusted by turning the bolts on the top using a screwdriver whilst connected to a Spectrum analyser.
• More commonly used in the Rx but can also be used on the Tx.
Band Stop Filter
• These notch out a specific set of frequencies.
• We commonly use them on smaller base station setups as an alternative to a duplexer.
Duplexer
• These filter both the Rx & Tx and output to a single Antenna.
• Spectrum planning is essential to ensure you’re using the correct frequencies.
Note: Please don’t retune them as they are linked on Rental point.
Cavity Filter
• Far narrower than a band pass filter these will Pass 3MHz (picture shown)
• We also own some 1MHz Cavity filters for use in crowded spectrums.
Note: Plan your frequencies carefully when using them.
• These are used in congested environments to eliminate as much unwanted RF as possible.
Combiners
• They combine 2 or 4 inputs into a single output.
• These can be quite lossy so make sure you increase the Tx power to compensate.
• They should have isolators already attached but if not make sure you pair them with isolators to protect your transmitters.
RSAs
• These are RF Distribution amplifiers for radio receivers.
• Tend to split in groups of 4 or 8.
Antennas
Dipole Antenna
• These come in 0, 3 & 6dB variants.
• 0dB antennas give a roughly equal gain both horizontally & vertically.
• 3dB antennas give more horizontal gain at the expense of vertical gain.
• Folded dipole antennas work in a similar way.
Note: They need to be mounted horizontally.
4 Stack Antenna
• These provide a 360° coverage with a 5° down tilt.
• Ideal for use on rooftops and on cherry pickers
Note: These are heavy so don’t put them on masts.
Yagi Antenna
• This is a directional antenna that features a reflector at the rear of the antenna to increase its forward gain.
• The more focusing elements the antenna has the more directional the antenna is.
Cables
IN RF Feeder
•IN RF feeder is measured in 3dB groups.
Note: It’s better to use 25m of LMR400 than 16m of LMR300.
•There are also ultra flex variants which can be identified by a rubber rather than plastic cable.
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