Using WiFi Antenna for 5G Mobile Network?

Question

I moved to an apartment located in a basement of a complex. I had to build a setup with a set of 2 external LTE (4G) antennas

1. Wilson Electronics Wideband Directional Antenna 700-2700 MHz
2. Wilson Electronics 4G Omni Residential Antenna 700-2700 MHz

And 2 Industrial Pepwave LTE routers from Peplink.

I would like to upgrade at least one of them to 5G. I borrowed a "Huawei 5G CPE Pro H112-372" from a friend to test the Internet speed at my place, from outside, speeds are decent. After connecting the router to my external antenna through a SMA-to-TS9 convertor and testing, results were horrible.

After more research, the datasheet for the H112-372 specifies the used 5G bands "5G: n41/ n77/ n78/ n79" Where the corresponding frequencies in MHz are as follows:

• n41: 2496 – 2690
• n77: 3300 – 4200
• n78: 3300 – 3800
• n79: 4400 – 5000

This is obviously outside the range of my current antennas. Currently there doesn't seem to be a lot of 5G antennas on the market, some are marketed as 5G ready like the Peplink "IP68 Omnidirectional LTE/GPS Antenna" with "Super Wideband 690-3800 MHz LTE" a very promising solution to my case, minus the "n79" band. Of course we are talking about sub 6 GHz bands here only.

As for the use of a WiFi antenna, there are some posts asking a similar question but for 3G/LTE (4G). I know that the used frequencies can range from 700MHz up to 2700 MHz depending on country and licensing of bands for both 3G and LTE (4G). So working with WiFi antennas depends on used frequencies. I had a friend who used to work for a telecom company and he said they used to reallocate their licensed spectrum between different technologies.

If a WiFi antenna is designed to cater for a specific narrow band at 2.4 Ghz and 5 GHz, then this is not a good option. But as per "IEEE 802.11y-2008" WiFi can be available as a licensed band at 3.65 GHz. Are there special antennas for these frequencies or they use the same WiFi antennas as everyone else?

If WiFi antennas are wide band antennas covering the range between 2.4 GHz up to 5 GHz, then can they be used for 5G mobile networks or not?

Notes:

5G features phased array antennas as a part of the technology to increase speed and efficiency. Obviously using an omnidirectional antenna wouldn't be as good as the complex internal router antenna at this stage.

Answer 1

Antennas work on resonant frequencies, which require an antenna design that targets the specific frequency range and impedance for the transceiver. Wide band antennas are rare over a large range of frequencies, and those usually have very low gain, since they can't really be tuned to a specific resonant frequency.

Most multiband antennas actually contain a series of more narrow band antennas, that are either combined on one feed(much like an old-school UHF/VHF television antenna), or have separate coaxial feeds for each internal antenna, which need to connect to separate ports on the transceiver which will feed each antenna signal to either multiple individual transceivers, or a diversity switch and filter combination that feeds a single transceiver.

Every multiband antenna I have seen recently is only resonant within the specific range of the three or four bands that it tries to cover. Outside or between those frequencies, the antenna will have almost no gain in comparison to the gain of the elements that are in-band.

TL/DR - A generic 2.4GHz-5GHz antenna will perform quite poorly trying to transmit or receive on the bands between or outside of those two frequencies...