This article will provide you with all the information you need to know about antennas, cables, and enclosures so you can pick the best combination for your hotspot setup.
The Short Answer
While the right enclosure depends on your hotspot, its size, and where you want to place it, there is an antenna and cable combination that will work for most scenarios. Before I share that antenna and cable combination, it is important to state that elevation is key. The more obstacles blocking your line of sight to other hotspots, the fewer hotspots you will witness. So no matter what antenna you have, make sure it is at least 10 feet above all surrounding obstacles, such as buildings, bridges, and hills. Keeping that in mind, a 5.8 dBi antenna with an LMR-400 cable is optimal for cases where the coax cable needs to be longer than 25 feet. However, for runs shorter than 25 feet, LMR-200 cable may be the better option because it is more cost effective with slightly more attenuation. We sell both N-Female to RP-SMA Male and N-Male to N-Female LMR-200 cable on our website.
Now we will take the time to go more in depth about which antenna may be the best choice for your hotspot setup.
How Elevation and Topography Affects Antenna Gain
First, we will talk about your elevation and topography and what it means for your setup. The flatter your topography is, the lower your elevation needs to be and the higher gain antenna you can use. This is because your radio signals will not have as many obstacles when traveling to other hotspots. They also will not have to account for the changes in elevation that non flat topographies have. If your topography includes a lot of tall buildings and hills, you will need to place a lower gain antenna at a higher elevation.
While lower dBi antennas are better at accounting for changes in elevation at shorter distances, higher dBi antennas sacrifice the ability to account for changes in elevation so they can reach farther distances. However, you should not exceed a gain of over 9 dBi otherwise the signal it gives off is too flat for most scenarios. It is also important to note that the max Effective Isotropic Radiated Power (EIRP) allowed by the FCC is 36 dBm for the 915 Mhz band in the United States. Since US915 hotspots start off by pushing 27 dBm, that means the maximum antenna dBi allowed in the US is 9 dBi.
The image below shows an outstanding example of how elevation and topography are important to consider when selecting the gain of your antenna. Since the blue car is at a higher elevation than the other car, it would need to have a lower gain antenna because a higher gain antenna would be too flat for it to pick up the radio signals of the other car below it. This shows how important it is to strategize the area of focus for your antenna before selecting the dBi.
Cables and Connectors
Now we will go over the different connectors that a variety of hotspots and antennas use, as well as the best types of coax cable to use for different applications.
Most hotspots have an RP-SMA Female connector on the back of them that the antenna would connect to. However, some hotspots may use SMA connectors.
What is the difference between SMA and RP-SMA?
RP-SMA stands for Reverse Polarity-SMA, which means the center conductor is on the female connector, whereas the center conductor is on the Male connector for SMA. However, the threads remain the same between the two. The male connectors have inner threads and the female connectors have outer threads. See the image below for a visual representation of each connector.
Since most hotspots have an RP-SMA Female connector, that means the antenna or cable that is connecting to the hotspot must have an RP-SMA Male connector. However, most antennas come with a pigtail that converts N-Type to RP-SMA.
What about outdoor antennas?
Outdoor antennas usually have an N Type connector, specifically an N Type Male connector. This means that you would have to have a coax cable that goes from RP-SMA Male on the hotspot end to N-Type Female on the antenna end. See the image below for a visual representation of each connector.
What type of cable should you use?
The type of cable you use mainly depends on how far your hotspot is from the antenna. If your hotspot is in an outdoor enclosure where it is only a foot or two away from the antenna, you will be fine using the included pigtail that comes with most antennas. The type of cable you use matters more when you are doing long runs of coax cable. The general rule of thumb is anything under 25 feet you are okay using LMR-200 cable, but for anything over 25 feet you will want to use an LMR-400 cable because it has lower attenuation over long runs. Many people refer to attenuation as dBi loss. See the chart below for a more detailed look at the attenuation difference between LMR-200 and LMR-400 coax cable at different lengths.
Finally, let’s look at what outdoor enclosures are available to you, and which one might be best for your situation. There are three important factors to consider when choosing which outdoor enclosure to use. These three factors are size, climate, and location.
When considering size, it is important to make sure that your hotspot will fit inside of the enclosure. Depending on which hotspot you have, there may be a little DIY involved. For example, the RAK Outdoor Enclosure is made for RAK hotspots. However, the SenseCAP M1 will fit inside but requires some retrofitting for how it is mounted. This can be done with safety straps, or even some double sided mounting tape. It is also important to note that the RAK outdoor enclosure comes with a PoE splitter that is not powerful enough for the SenseCAP M1, but we will offer this upgrade on our website soon.
Next we move on to climate. Since climate varies considerably depending on your location, it is important to make sure both your hotspot and enclosure can handle the outdoor elements in your region. It is important to make sure you are purchasing a weatherproof enclosure, preferably rated IP67 / NEMA-6 or higher.
LOCATION, LOCATION, LOCATION! Last but not least, the location where you are planning to install your outdoor enclosure is the most important factor to consider when purchasing an enclosure. Depending on the location of your install, you may need to purchase additional equipment. For example, if you wanted to install it on your roof, you would need a mast. This would also require an extension cable or PoE setup to power your hotspot and provide internet. Another example would be an upgraded antenna, this would require additional mounting and grounding hardware.
The RAK outdoor enclosure kit provides an easy way to upgrade your indoor hotspot into an outdoor hotspot that is PoE compatible. The enclosure itself is all metal and comes with cutouts for an antenna and an ethernet gland to provide internet and power to your hotspot.
The RAK Outdoor Enclosure Kit Includes:
- Ethernet gland
- PoE splitter Type-C USB (in 48V; out 5V/2.4A)
- PoE injector (in 100-240V; out 48V/0.5A)
- US 120v Power cord for the PoE Injector
- Zip Tie, PVC Tape, and Waterproof Tape
- Antenna Cable Type RG 1.32, With N-Type To RP-SMA Male Connectors.
The Parley Labs Outdoor Conversion Bundle Includes:
- RAK Outdoor Enclosure Kit
- 8 dBi Antenna (Gray)
- Lighting Arrester
- Coax Sealing Tape
- N-Type Male to N-Type Female Cable (5 ft)
Beyond the RAK outdoor enclosure, there are hundreds, if not thousands, of plastic enclosures to choose from online and in stores. The three important factors for choosing one, as mentioned above, are size, climate, and location.
Key Words / Phrases
dBi – The gain of an antenna system relative to an isotropic radiator at radio frequencies.Elevation – The height of your hotspot in relation to the ground.Lines of Sight – A straight line between hotspots where they have unobstructed vision.Topography – Everything that surrounds, channels, and blocks your radio signals. Some examples include buildings, earth, and water.
More Information and Sources
Antennashttps://kyk13.com/antennas-for-helium/https://unsealed4x4.com.au/picking-the-right-uhf-antenna-for-your-4×4/ Cables and Connectorshttps://www.spo-comm.de/en/blog/know-how/what-is-the-difference-between-sma-and-rp-smahttps://www.universal-radio.com/catalog/cable/coaxperf.html FCC Regulationshttps://transition.fcc.gov/oet/ea/presentations/files/oct07/Oct_07-Basics_of_Unlicensed_Trans-JD.pdfhttps://www.multitech.com/support/resolutionid/5086522