Choosing antennas for your connectivity solution

Why use an external antenna?

The #1 question we get when we sell a cellular router for a boat is, "will I need an external antenna? " Typically a set of external cellular and / or Wi-Fi antenna elements mounted outside your boat will give you better range and better overall performance. However a lot of factors impact whether you need external antennas and what type of antenna makes most sense. This article walks through both the considerations for antenna selection as well as recommendations based on your requirements.

Considerations for antenna selection

Before discussing antenna options, it is important to note that most routers require two or four cellular antenna connections and typically two Wi-Fi antennas. When you purchase your router, it will typically come with the appropriate number of stick or paddle antennas that can be attached and used for basic installations.

Modern 5G and LTE Cat-18 or better modems require four cellular antennas. Cat-6 and Cat-12 LTE modems typically use two cellular antennas.

All antenna ports should be connected to an antenna element and ideally these elements should be the same type and spaced correctly. To save the hassle of installing multiple individual antennas, there are several external antenna products that have 2 or 4 matched cellular antenna elements in a single enclosure and these elements are mounted inside to optimize spacing, diversity and orientation which greatly simplifies installation.

In addition, modern routers typically have two Wi-Fi antenna ports. Again, these ports could be connected to individual matched single antennas or combo antennas that have multiple elements.

Wi-Fi WAN

Wi-Fi antenna selection has its own set of considerations. Most Peplink routers have a single set of Wi-Fi radios (2.4 and/or 5GHz) connected to a single pair of Wi-Fi antennas. Yet, these radios can serve two separate functions. First, the Wi-Fi radio is used to establish an access point or “hotspot” for your boat. This Wi-Fi LAN is what your users connect their devices to. Second, the Wi-Fi radios can also be used for Wi-Fi WAN which is the ability to connect to external Wi-Fi hotspots (such as marina Wi-Fi). This allows you to use that Wi-Fi as your connected path to internet instead of or even in addition to cellular. Wi-Fi WAN is very popular as it gives you a way to connect your router and users to the internet without racking up cellular data usage charges. However, if you plan on using Wi-Fi WAN a lot, you’ll want to locate your Wi-Fi antennas outside the cabin to get the best signal from the remote Wi-Fi source and that may compromise your onboard Wi-Fi LAN network performance if your users are far away from the Wi-Fi antennas outside. Plus if your router is using both Wi-Fi WAN and Wi-Fi LAN there is a small performance hit as the Wi-Fi radios are splitting time performing both tasks. For this reason, many customers choose a strategy of using the router for external communications via cellular and Wi-Fi WAN and add a dedicated access point device inside the cabin to provide Wi-Fi LAN functionality.

On some boats, where there is a dry place to install the router and there is a good path through glass or fiberglass to the remote cellular and Wi-Fi transceivers you are communicating with, the bundled stick antennas may work fine.

Often though, we get asked what antenna should be used to get maximum range and performance especially in more remote areas that are far from cell towers.

Before considering which external antenna to purchase, there are some factors that will impact any antenna installation:

Location: The antenna needs to be installed far from other vertical metal and transmitting antennas or devices if possible. NMEA typically recommends 2-6 feet separation depending on the type of the other antenna. Cellular antennas should never be installed in the beam of a radar. Keep in mind any vertical metal can cause interference or reflection which can degrade the performance of the router / antenna combo. Imagine the path to the cell tower or external Wi-Fi source antennas and try to keep that path as unobstructed as possible.

Cable length: Antenna cables that are too long are often the downfall of many antenna installations. HDF-195 (aka LMR-195) is widely used for the six-foot cables attached to many antennas as well as for shorter extension cables. We don’t recommend having a total cable run of more than 20 feet if you are using HDF-195. Using the Times Microwave Coax Cable Attenuation Calculator, you can see that for 5000Mhz the loss is 6.2dB plus probably another 0.5dB loss for the mid-point connector. For longer runs you will need to step up to LMR-400 UltraFlex which brings the loss down to 2.8dB for 20 feet but that presents a new set of challenges as you plan for cable routing. Given this, the goal is to install the router as close as possible to the antenna installation area in order to minimize loss from cable runs. Otherwise, if you cable run is too long you will defeat the point of installing an external antenna.

Want to learn more about the new Peplink Maritime series antennas?

Check out the SeaBits review of the Peplink Maritime 20G and 40G antennas.

Antenna size and esthetics: External antennas range in size from small, lightweight domes such as the Peplink Mobility 40G 4x4 MIMO LTE/5G/GPS Antenna to large and heavy “stick” style antennas like the Peplink Maritime 40G Antenna. The larger antenna will typically perform better but may be a beast to install on your antenna array arch or aft rail. We have seen many customers also choose to use two antennas instead of one for visual balance, such as using two Peplink Maritime 20G Antennas with a typical 4x4 cellular modem setup.

Performance and range goals: As they say, the bigger the better. The bigger the antenna elements along with an installation location free and clear from surrounding clutter will typically result in the best possible range and fastest speeds. With that in mind, the three-plus-foot Peplink Maritime 40G Antenna has been the go-to antenna for folks wanting reception in the most remote areas. A fine alternative that appears to provide similar performance is the Poynting OMNI-414 MIMO 4x4 LTE/5G Antenna. It is a bit smaller but in our testing has done almost as well as the Maritime 40G. But if your performance requirements are less demanding, you are cruising in more populated areas or if you have a smaller boat, then a small external dome style antenna may be more appropriate and work very well.

Wi-Fi WAN: If connecting to external marina and public Wi-Fi is important then install external Wi-Fi antennas and use a separate dedicated access point (AP) such as the Pepwave AP One AX Lite Wireless Access Point in the cabin.

Other options: A creative way to address many of these challenges is to go with a solution that has the cellular modem and antennas located in the same enclosure. Options for doing this include:

• Place the router and a smaller external antenna such as the Peplink Mobility 42G Combo LTE/Wi-Fi/GPS Antenna in an unused satellite or TV antenna dome enclosure. Bring power up to the dome and lead an ethernet cable down to the cabin where you can install a dedicated access point.
• Go with the Peplink MAX HD1 Dome Pro Router with a 5G router which uses Power-over-Ethernet (PoE), 4x4 cellular antennas and Wi-Fi antennas in a single dome. Install your SIM cards in the dome or use the optional Peplink SIM Injector Mini and bring a single ethernet cable down to a PoE inserter and your access point in the cabin.
• Build your own dome using the new Poynting EPNT-1 Omni-Directional Combo Antenna with Enclosure with your router of choice inside. This unique product has four cellular and two Wi-Fi antennas built into a waterproof enclosure and there is room in the enclosure to install your router. By only needing cables that are a few inches long, you get the full benefit of the high-gain antennas with virtually no antenna cable loss. We even have a solution for converting your router into a PoE powered device. Plus with the Wi-Fi antennas, this is a fantastic solution for enhanced Wi-Fi WAN connectivity. See our article here for how to build out this solution.

For all three of these solutions, you can locate the modem/antenna set pretty much anywhere you like and lead no-loss ethernet down to your cabin. I am a big fan of the EPNT solution and have been using it with a 5G router on my own sailboat very successfully for several very wet Pacific Northwest months.

Recommendations

Given all that, which antenna setup should you choose?

Here is our basic set of recommendations based on whether you plan on using a lot of Wi-Fi WAN or not.

Two more considerations...

Finally, there are (at least) two other factors to consider when choosing antennas and installations locations: antenna mounts and cables.

Antenna mounts

Some of our antennas such as the Poynting OMNI series and the Peplink Maritime series come with a 1-inch 14TPI female receiving port on the bottom which can be twisted onto any standard 1 inch marine mount. Other antennas such as the Peplink Mobility series requires the Peplink Antenna Mount for Peplink Mobility Antennas to fix these to a 1-inch marine mount. The Peplink MAX HD1 Dome requires both a Peplink Antenna Mount for MAX HD Dome and a Peplink Antenna Mount for Peplink Mobility Antennas to use this with a 1-inch marine mount.

If you need to add height, consider an extension such something like the Shakespeare 4008-4 Fiberglass 4 Foot Mast for Antenna Mounts or build a custom extension using our parts from Morad. At the bottom of the mount or pole, make sure you accommodate the cable run. Given the number of cables involved with these combo antennas, a solution such as Morad M93 Female-Male Thread Adapter is very useful for passing the cables outside the mount before attaching the whole assembly to a marine mount such as a Morad M99 Stainless Steel Ratchet Mount or the Peplink Antenna Base Mount.

Feel free to contact us if you have questions on which mounting hardware to buy.

Cables

As mentioned earlier, it is important to keep your cable runs as short as possible. Again, a total run of 20 feet is about the maximum you can go with HDF-195 for use with cellular antennas. We sell some pre-built twin, 5-in-1 and 7-in-1 cable sets in various lengths. If you need other custom configurations or longer lengths with LMR-400, consider acquiring these at a cable specialty shop such as ShowMeCables.

Example installations

To finish, I have included a few sample installations. Please note, since I am constantly testing new antennas, I tend to have temporary cable runs. In a finished installation, this could be done differently.

	In this example, I am using a Peplink Mobility 42G attached to a Peplink Antenna Mount for Peplink Mobility Antennas which is then attached to a Morad M93 Female-Male Thread Adapter to allow the cables to pass out the side before being attached to a rail mount.
	This is the Peplink Mobility 42G installed on the top of a Morad stanchion extension system.
	In this installation, I have a Peplink Maritime 40G Cellular Antenna attached to a 4-foot Shakespeare extension attached to my davits.
	In this example I have a Poynting EPNT-1 Omni-Directional Combo Antenna with Enclosure with a MAX Transit 5G inside on the same pole mount with a Peplink Maritime 40G Cellular Antenna connected to a Pepwave MAX BR1 Pro 5G Router installed inside the cabin. I used a Poynting Extension Cable for 7 in 1 Antennas kit to extend the cables to a total of 16 feet.
	In this example I have a Poynting OMNI-414 MIMO 4x4 LTE/5G Antenna on a rail mount attached to my davits and connected to a Pepwave MAX BR1 Pro 5G Router installed inside the cabin. I used a Poynting Extension Cable for 7 in 1 Antennas kit to extend the cables to a total of 16 feet.

If you have questions or need further help, either leave a comment below or contact us.

Doug Miller