Grazioli Antennas G-Max 10 & 11 Meter 5/8-Wave Collinear Vertical Antennas are the world's first and only vertical antennas for the 10 and 11 meter bands to utilize a true 5/8-wave collinear configuration, delivering gain well beyond that of a conventional 1/4-wave design. Built on the proven mechanical platform of the FE10V, the G-Max delivers performance comparable to, and in some cases surpassing, that of a 2-element Yagi while maintaining the key advantage of omnidirectional coverage. The G-Max stands apart from conventional vertical antennas, including 5/8-wave, J-Pole, and other competing designs. Its high gain, compressed radiation pattern, and low-angle radiation characteristics provide outstanding local and DX performance, setting a new benchmark for omnidirectional 10 and 11 meter operation.

Materials & Construction

The antenna is constructed from AW6063-T66 aluminum alloy, a high-strength aluminum-magnesium-silicon alloy hardened to the T66 temper. This material provides exceptional durability through an extrusion and cold-drawing process. Precision-manufactured tubing maintains tight tolerances for both diameter and wall thickness, ensuring accurate fitment with minimal play between sections.

The ground plane consists of four heavy-duty 8.9-foot full quarter-wave radials built from two telescoping sections secured with clamps. Radial sections measure 0.50 and 0.39 inches in diameter. The radials are attached to the support plate using U-bolts and self-locking nuts, while four fiberglass reinforcements strengthen the mounting points and help prevent tube deformation during installation and operation.

The Phasing Correction Coil

The G-Max phase coil is strategically positioned between the two central radiating sections and performs three critical functions essential to the antenna's collinear design.

First, it introduces a 180° phase shift between the lower 1/4-wave section and the upper 5/8-wave section, ensuring the entire radiating element operates in phase for maximum efficiency.

Second, the coil compensates for the significant capacitive reactance present in the upper 5/8-wave section through its inherent inductive reactance.

Third, it transfers RF power to the upper radiating section with minimal loss, maintaining efficient energy distribution throughout the antenna.

These functions are made possible by the coil's high-Q design, engineered to provide precise phase control, effective reactance compensation, and low-loss power transfer for optimum performance.

The UHF connector

Unlike the commercial SO-239 connectors commonly used by many manufacturers, the FE10V connector was designed and manufactured entirely by Grazioli. Engineered with a true 50-ohm impedance and rated for operation up to 500 MHz, it was specifically developed to provide exceptional reliability and withstand continuous CW power levels up to 5 kW at 30 MHz.

The connector body is machined from nickel-plated CW614N brass, while the center pin features a 24K gold-plated finish to resist oxidation and ensure long-term conductivity. A four-fin contact design maintains precise centering and contact pressure, minimizing insertion losses and ensuring reliable electrical performance.

The insulating components are manufactured from PTFE (polytetrafluoroethylene), one of the industry's most effective dielectric materials, offering a low dielectric constant, minimal loss factor, and excellent thermal stability across temperatures ranging from -100°C to +260°C. A specially designed elastomer protective cap seals the connector against moisture and water intrusion, helping ensure dependable operation in demanding outdoor environments.

The Fixing Bracket

The heavy-duty mounting bracket is manufactured from 0.09 in. (2.5 mm) thick AISI 304 stainless steel for excellent strength and corrosion resistance. It attaches to the antenna tube using a clamping system that provides an exceptionally secure mechanical connection.

Mast mounting is accomplished with AISI 304 stainless steel M6 V-bolts and high-profile nuts, allowing for easy installation and secure tightening while ensuring long-term durability in outdoor environments.

Additional Features & Specifications:

• Radiation Type: Omnidirectional

• Polarization: Linear Vertical

• Gain: 3.5 dBd (5.65 dBi)

• Bandwidth (SWR 2:1): ≥ 1.3 MHz @ 27 MHz

• SWR at Resonance: ≤ 1.2 typical, < 1.1

• Feed System: Direct feed with DC-ground choke

• Input Connector: 50 Ω UHF SO-239 female, PTFE insulator, gold-plated pin

• Maximum Input Power: 5,000 watts continuous, all modes

• Antenna Height (with mounting tube): 35.60 ft. (10.85 m)

• Radial Length: 8.90 ft. (2.7 m) (full quarter-wave)

• Mounting Mast Diameter: 1.57–2.12 in. (40–54 mm)

• Wind Survival (with guy ropes, no ice): 80.78 MPH (130 km/h)

• Antenna Net Weight: 15 lbs. (6.8 kg)

• Package Dimensions: 5.50 × 5.50 × 57.0 in. (14 × 14 × 145 cm)

• Shipping Weight: 18.07 lbs. (8.2 kg)