CISCO POINT-TO-POINT RF PLANNING
Cisco AIR-ANT3338 and AIR-ANT58G28SDA-N Selection Guide
Compare two legacy Aironet dish antennas by frequency, gain, connector, beamwidth and lifecycle before sourcing a point-to-point WLAN replacement.
The two dish antennas are not interchangeable
AIR-ANT3338 is Cisco's 2.4 GHz solid dish antenna with 21 dBi gain and an RP-TNC connector. AIR-ANT58G28SDA-N is a 5.8 GHz dish antenna with 28 dBi gain and an N-male connector. The higher gain of the 5.8 GHz model does not make it an upgrade for a 2.4 GHz radio; frequency and radio-port compatibility must match first.
| Selection field | AIR-ANT3338 | AIR-ANT58G28SDA-N | Design consequence |
|---|---|---|---|
| Frequency | 2.4 to 2.83 GHz in Cisco specifications. | 5.725 to 5.825 GHz in Cisco specifications. | Match radio band and regional authorization. |
| Gain | 21 dBi. | 28 dBi. | Include gain in EIRP and receive-level calculations. |
| Connector | RP-TNC. | N-male. | Verify radio port, cable and adapter loss. |
| Polarization | Vertical. | Field configurable vertical or horizontal. | Both ends of the link must use the intended polarization. |
| Nominal 3 dB beamwidth | 12.4 degrees in azimuth and elevation. | 4.75 degrees in azimuth and elevation. | The narrower 5.8 GHz model demands more precise alignment. |
These are single-purpose directional antennas, not access points. A working link also requires compatible radios, approved cable assemblies, mounts, grounding, surge protection and a clear path.
Calculate the complete link, not antenna gain alone
Start with radio transmit power and subtract cable, connector and adapter losses before adding antenna gain. Perform the same accounting at the remote end and compare the estimated receive level with the radio sensitivity for the required data rate. Preserve fade margin for weather, installation tolerance and environmental change.
Effective isotropic radiated power must remain within the applicable local limit. A high-gain dish can require lower configured transmitter power. Regulatory limits, permitted channels and dynamic frequency selection differ by band and jurisdiction, so a part number cannot determine legal operating power by itself.
- Radio PID, regulatory domain, channel width and configured transmit power.
- Antenna PID, gain, polarization and radiation pattern.
- Cable type and length, plus every connector and surge-protector loss.
- Path length, Fresnel-zone clearance, terrain and obstruction survey.
- Required modulation, receive sensitivity and target fade margin.
Narrow beamwidth changes installation practice
The 4.75-degree beamwidth documented for AIR-ANT58G28SDA-N is substantially narrower than the 12.4-degree value for AIR-ANT3338. Visual pointing alone is not sufficient for a reliable long-distance link. Use a stable pole, coarse bearing and elevation planning, then align against live receive-level or signal-quality measurements from both ends.
Structure
Check mast diameter, bracket completeness, wind loading, corrosion and movement. A small angular shift can materially reduce a narrow-beam signal.
RF path
Confirm line of sight and Fresnel clearance. A visible remote site does not guarantee adequate RF clearance.
Weatherproofing
Inspect connectors, drip loops, grounding and surge protection. Seal outdoor joints using the radio and antenna installation requirements.
Document final azimuth, elevation, polarization, received signal, noise floor, negotiated rate and error counters. That record makes later fault isolation possible after a storm, roof project or mast movement.
Both models are legacy, end-of-sale parts
Cisco's lifecycle bulletin includes both AIR-ANT3338 and AIR-ANT58G28SDA-N among the affected antennas and states that no direct replacement was available in that notice. Procurement of remaining or secondary-market stock should therefore focus on exact identity, physical completeness and compatibility rather than assuming manufacturer-new availability.
Inspect the reflector, feed assembly, connector threads, radome or protective parts, pole hardware and evidence of water intrusion. For an existing bridge, capture radio configuration and baseline signal before replacing either antenna. For a new link, evaluate current supported Cisco antenna and radio combinations instead of designing a fresh dependency around an obsolete part.
Legacy dish antenna purchase checklist
- Match the band: use AIR-ANT3338 only for the documented 2.4 GHz range and AIR-ANT58G28SDA-N for its documented 5.8 GHz range.
- Match connectors: confirm RP-TNC versus N-male and calculate cable-system loss.
- Verify completeness: require photographs of reflector, feed, connector and mounting hardware.
- Plan regulation: calculate EIRP and permitted channels for the deployment country.
- Survey the path: confirm distance, Fresnel clearance, mounting structure and wind exposure.
- Align instrumentally: record signal at both link ends, not only visual bearing.
- Document lifecycle: record that the part is end of sale and maintain a supported replacement plan.
Related product records
Use exact model pages to prevent a 2.4 GHz and 5.8 GHz dish from being quoted as substitutes.
Official manufacturer sources
- Cisco select Aironet antennas end-of-sale and end-of-life bulletin
- Cisco Aironet and Catalyst antenna reference guide
- Cisco Aironet antenna specifications
- Cisco RF power values and antenna gain reference
This independent selection guide is not a Cisco publication and does not claim partner authorization. Radio regulations vary by country; verify the complete radio, antenna and cable system before installation.