How to Connect an External Antenna to Zyxel FWA505 and FWA515

The Zyxel FWA505 and Zyxel FWA515 are 4G LTE / 5G Fixed Wireless Access (FWA) routers designed for locations where wired broadband is unavailable or unreliable.
In areas with weak mobile signal, using an external antenna is one of the most effective ways to improve signal strength, stability, and overall throughput.

However, many users experience difficulties when trying to connect an external antenna due to connector incompatibility.
This article explains:

• which external antennas are recommended for FWA505 / FWA515;

• which antenna connectors are used on these devices;

• why most standard antennas cannot be connected directly;

• how to use SMA → TS-9 adapters correctly;

• why using two antennas is strongly recommended instead of one.

According to Zyxel recommendations, the following antenna characteristics are advised:

Antenna Type

• Outdoor directional antenna (best for long distance to base station)

• MIMO 2×2 or 4×4 support

• Compatible with LTE and 5G NR frequency bands used by your mobile operator

Antenna Gain

• Recommended gain: 7–11 dBi

• Very high gain antennas are not always better and may cause instability if misaligned

Installation Guidelines

• Outdoor installation (wall, pole, or mast)

• Correct alignment toward the mobile base station

• Keep antenna cables as short as possible to reduce signal loss

Which connector is used on FWA505 / FWA515?

Zyxel FWA505 and FWA515 use TS-9 antenna connectors
(sometimes also referred to as ES9).

Why most antennas do not connect directly

Most external LTE/5G antennas on the market are equipped with SMA Female connectors.
These cannot be connected directly to the TS-9 ports on the router.

Component	Connector type
Typical external antenna	SMA Female
FWA505 / FWA515	TS-9

Using SMA → TS-9 Adapter Cables

Required adapter

To connect an SMA-based antenna, you must use a pigtail adapter:

• SMA Female → TS-9

• Typical cable length: ~15 cm

⚠️ Important warning
Some adapters are sold as CRC9 / TS-9.
Although they look similar, CRC9 and TS-9 are different connectors.
FWA505 and FWA515 require TS-9. Using the wrong adapter may cause poor contact or damage.

Can You Use Only One External Antenna?

Yes, one antenna can be connected

The router will operate with:

• a single external antenna,

• improved signal strength compared to internal antennas,

• acceptable performance in moderately weak signal areas.

This may be sufficient if:

• only one antenna is available,

• signal quality is already relatively stable,

• a simple setup is required.

Why Two Antennas Are Strongly Recommended

MIMO technology explained

FWA505 and FWA515 use MIMO (Multiple Input Multiple Output) technology, which:

• transmits and receives data using multiple radio paths,

• improves speed, reliability, and resistance to interference,

• is essential for LTE-Advanced and 5G performance.

Benefits of using two antennas

When two external antennas (or one MIMO antenna with two cables) are connected:

• ✅ Full MIMO mode is enabled

• ✅ Better signal quality (RSRQ / SINR)

• ✅ Higher real-world download and upload speeds

• ✅ More stable connection during peak hours

What happens with only one antenna

With only one antenna connected:

• MIMO works partially or is disabled,

• performance may drop closer to SISO mode,

• maximum LTE / 5G throughput cannot be achieved.