Terahertz and Emerging Frequencies Sub-THz and D-band Informational

How do I design an antenna for operation at 140 GHz for wireless backhaul?

Designing an antenna for 140 GHz wireless backhaul requires achieving high directivity (typically 40-45 dBi) to overcome the high free-space path loss. The three primary architectures are Cassegrain reflector antennas (25-40 cm diameter dishes providing 40-48 dBi gain), dielectric lens antennas (HDPE or Rexolite lenses fed by a planar antenna), and planar phased arrays (enabling electronic beam steering but limited by losses at 140 GHz). At 140 GHz with lambda = 2.14 mm, a 30 cm dish provides approximately 42 dBi gain. The surface accuracy must be better than lambda/20 (approximately 100 micrometers). The waveguide interface is WR-6.5 or WR-5.1.

Category: Terahertz and Emerging Frequencies

Updated: April 2026

Product Tie-In: D-band Components, Waveguide, InP Devices

High-Gain Antenna Options for D-Band Wireless Backhaul

The antenna is critical for D-band backhaul because the high free-space path loss (141 dB at 2 km) demands substantial antenna gain.

Parameter	Option A	Option B	Option C
Performance	High	Medium	Low
Cost	High	Low	Medium
Complexity	High	Low	Medium
Bandwidth	Narrow	Wide	Moderate
Typical Use	Lab/military	Consumer	Industrial

Technical Considerations

The standard choice for point-to-point backhaul. At D-band, a 30 cm Cassegrain provides approximately 42 dBi gain with a 0.6-degree beam width. Surface accuracy better than 100 micrometers is required.

Performance Analysis

Dielectric lens antennas focus the beam using a shaped lens (HDPE, Rexolite, or silicon). A 10 cm HDPE lens provides about 37 dBi gain at 140 GHz.

Design Guidelines

Phased arrays offer electronic beam steering but at 140 GHz, element spacing of ~1 mm requires dense integration. A 40 dBi array needs approximately 5,000 elements.

Implementation Notes

With beam widths of 0.5-1.0 degrees, D-band antennas require precise alignment (better than 0.1 degrees). Auto-tracking systems may be necessary for long links.

Performance verification: confirm specifications against the application requirements before finalizing the design
Environmental factors: temperature range, humidity, and vibration affect long-term reliability and parameter drift
Cost vs. performance: evaluate whether the application demands premium components or standard commercial grades
Interface compatibility: verify impedance, connector type, and mechanical form factor match the system architecture

Practical Applications

When evaluating design an antenna for operation at 140 ghz for wireless backhaul?, engineers must account for the specific requirements of their target application. The optimal choice depends on the frequency range, power level, environmental conditions, and cost constraints of the overall system design.

Common Questions

Frequently Asked Questions

What surface accuracy is needed for a D-band reflector antenna?

For less than 1 dB gain loss at 140 GHz, the surface RMS error should be below lambda/20 = 107 micrometers. This is readily achieved with CNC-machined aluminum.

Can I use a flat-panel antenna for D-band backhaul?

Yes. Planar slot array antennas can achieve 30-35 dBi gain at 140 GHz in a flat form factor.

How narrow is the beam at D-band with a typical backhaul antenna?

A 30 cm dish at 140 GHz produces a 3 dB beam width of approximately 0.5 degrees.

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