Antennas for WISP Fixed Wireless Access Networks
KP Performance Antennas, Edmonton, Alberta, Canada
Developments in spectrum allocations in the U.S. and Canada should be good news for the Wireless Internet Service Provider (WISP) industry, which offers broadband data and VoIP voice access to rural areas, IoT connectivity, and other applications. In the U.S., the FCC loosened rules governing the 5-GHz unlicensed Wi-Fi bands and created the Broadband Radio Service (CBRS) at 3.5 GHz, and in Canada the government has opened new spectrum at 5 GHz. To address these new opportunities, KP Performance Antennas has expanded their current line of antennas for WISP applications in each band.
The benefits for WISPs in the U.S. are two-fold. First, creation of CBRS is one of the most promising FCC rulemakings in many years, as it offers 150 MHz of shared spectrum between 3550 and 3700 MHz with few limitations on the types of services as long as they use a digital transmission scheme, which in most cases is likely to be LTE.
CBRS uses a three-tiered approach that protects incumbent services, mostly Navy coastal radars, from interference from the two lower tiers. The tier below the incumbents is the Priority Access Licensee (PAL) that will obtain 10-MHz channels through FCC auctions. They can operate within 100 MHz (3550 to 3650 MHz) of the total available bandwidth.
As each license covers only a small geographical area (a census tract), the FCC believes this will drive down the auction price and make it more appealing for organizations with fewer resources than the major wireless carriers to establish new types of services at these frequencies. The lowest tier called General Authorized Access (GAA) costs operators nothing but also gets no interference protection from the higher-tier services. In practice, it’s likely that a GAA user will be able to use about 80 MHz in each tract.
Along the benefits from more frequencies to operate on, WISPs stand to gain because the propagation characteristics at 3.5 GHz are somewhat better than those at 5 GHz, so capacity and coverage should be less expensive to achieve. As PAL tracts are small and will presumably be reasonably affordable, WISPs can also pick and choose areas where coverage is needed.
For CBRS (and other applications between 3400 to 3800 MHz), KP has introduced the KPPA-3S3S-65SS quad-polarization sector antenna (Figure 1). It combines two complete radiating systems in a single rugged radome and has gain of 17.5 dBi, power handling of 50 W, slant ± 45 deg. polarization, a temperature range of -40° C to +60° C, 65-deg. 3-dB azimuth beamwidth, and 3-dB elevation beamwidth of 6.9 deg.
Figure 1. The KPPA-3S3S-65SS is a quad-polarization sector antenna well suited for operation in the CBRS band in the U.S. as well as WISP frequencies in Canada and other countries
The second U.S. development changes the FCC rules governing use of the 5150 and 5250 MHz Unlicensed National Information Infrastructure (U-NII-1) bands. The most appealing aspect of the rule changes for WISPs is their increase in the maximum Effective Isotropic Radiated Power (EIRP) to 4 W. The rulemaking wasn’t targeted specifically at the WISP market, but rather to improve improving IEEE 802.11ac Wi-Fi capacity and speeds. However, many WISPs use Wi-Fi as their transmission scheme so they should benefit as well.
The Canadian allocation is more directly aimed at the WISP industry, as it addresses fixed point-to-multipoint and point-to-point services. The opportunity was created in May when Canada authorized the use of higher power and outdoor network devices indoors and outdoors between 5150 and 5250 MHz. The ruling provides 100 MHz of additional spectrum for WISPs, doubling their current allocations in the 5 GHz band.
In addition to its other antenna systems for WISP applications, the company recently introduced the dual-band KPPA-2HV5HV-90SS and KPPA-3S5HV-90SS sector panel antennas that combine two complete radiating systems within a single ruggedized radome. The design effectively eliminates the need for different antenna structures for each band, reducing tower rental and installation costs. The KPPA-2HV5HV-90SS covers 2300 to 2700 MHz and 5200 to 5900 MHz and the KPPA-3S5HV-90SS covers 3500 to 3800 and 5400 to 5900 MHz.
The KPPA-2HV5HV-90SS has a 90-deg. azimuth 3-dB beamwidth, gain of 15.2 dBi in one port and 15.9 dBi in the other, a front-to-back ratio of 26 and 28 dB, and cross polarization ratio greater than 29 and 30 dB. It is 28.5 in. high and weighs 8.5 lb. The KPPA-3S5HV-90SS has a 90-deg. azimuth 3-dB beamwidth gain of 15.9 and 17 dBi, front-to-back ratio of 28 dB, and cross-polarization ratio of 17 and 30 dB. It is 27.5 in. high and weighs 9 lb.
Both models are rated for IP55 rain resistance, have an operating temperature range of -40o to +60o C, handle RF input power of 50 W, and can withstand wind speeds up to 100 mi/h. The KPPA-2HV5HV-90SS is designed for Cambium Networks PMP and ePMP radios and the KPPA-3S5HV-90SS is designed for these radios as well as Ubituiti Networks’ UBNT radios. The antennas are supplied with weatherized cases for the radios and an adapter if external mounting is desired.
For subscriber locations, KP offers base station antennas for all WISP operating frequencies including 900 MHz, and 2, 3, and 5 GHz, as well as Yagis, reflectors, omnidirectional, grid, and feedhorns for subscriber installations.
Originally published for Microwave Journal, November 2017