GRA-UR90-CF Portable Umbrella RF System
The GRA-UR90-CF is a portable umbrella-type RF Counterpoise and Capacity Hat system built from premium Japanese Toray carbon fiber. Designed to improve HF antenna efficiency without significantly increasing antenna height, it can be installed either at the antenna base or antenna top for enhanced portable operation.
Why Choose GRA-UR90-CF?
Portable HF antennas are often shortened to improve portability.
However, shorter antennas frequently suffer from:
- Reduced radiation efficiency
- Increased loading coil losses
- Narrower bandwidth
- Longer tuning time
- Reduced DX communication performance
The GRA-UR90-CF was developed to improve the operating efficiency of compact HF antennas without requiring a significant increase in overall antenna height.
Premium Toray Carbon Fiber Construction
Unlike low cost carbon powder injection molded products, the GRA-UR90-CF is manufactured using genuine Japanese Toray carbon fiber cloth.
Each layer is carefully stacked and compressed under high pressure to achieve exceptional structural integrity.
Benefits include:
- Up to 99% carbon content
- Extremely high strength
- Excellent durability
- Superior rigidity
- Lightweight portable design
Two Installation Modes
RF Counterpoise Mode
Installed near the antenna base, feed point, or mast.
Functions as an artificial RF ground system.
Benefits:
- Creates RF return path
- Improves grounding conditions
- Reduces dependency on radial wires
- Enhances portable deployment efficiency
Ideal for:
- Beaches
- Concrete surfaces
- Mountain operations
- Parking lots
- Marine environments
- Temporary field stations
Capacity Hat Mode
Installed at the top of the antenna.
Benefits:
- Increases top loading capacitance
- Improves current distribution
- Reduces loading coil losses
- Improves low band radiation efficiency
- Enhances transmission performance
Particularly beneficial on:
- 80m Band
- 60m Band
- 40m Band
Recommended Compatibility
Directly compatible with:
- GRA-7350T(C)
- GRA-RPG
- GRA-AT330T(C)
All use the Japanese M10 x 1.0P thread standard.
Additional installations can be achieved using Gabil adapter systems.
Product Specifications
Model: GRA-UR90-CF
Power Rating: 400 W
Weight: Approx. 5.3 oz (150 g)
Expanded Size: Approx. Ø37.2 in × 41.1 in (Ø94.5 cm × 104.5 cm)
Packed Length: Approx. 21.9 in (55.5 cm)
Connector: M10 × 1.0P
Material: Carbon Fiber
Typical Applications
- HF Vertical Antennas
- Portable Mast Antennas
- Marine Communication Antennas
- ATU Systems
- Tactical Communication Equipment
- Field Deployable Antenna Systems
- POTA Operations
- SOTA Operations
- DX Communications
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