The Diamond SGM504 is an ultra-compact, high-performance dual-band mobile antenna engineered specifically for amateur radio operators who require a low-profile yet highly efficient communication setup on their vehicles. Part of Diamond Antenna’s legendary Super Gainer series, this premium whip is designed to operate on both the 2-meter (144 MHz) VHF and 70-centimeter (430 MHz) UHF bands. Its streamlined, unobtrusive profile makes it an excellent choice for city driving, low-clearance parking garages, or mounting on compact vehicles, without compromising on signal integrity or mechanical durability.
Measuring just 0.4 meters (40 cm) in length and weighing a lightweight 160 grams, the SGM504 is engineered to minimize wind resistance and physical strain on your vehicle’s antenna mount. Despite its compact footprint, the antenna utilizes a sophisticated dual-wave electrical design. On the 144 MHz VHF band, it functions as a highly reliable 1/4 wave antenna, while on the 430 MHz UHF band, it operates as a 1/2 wave radialless whip, delivering a concentrated gain of 2.15 dBi. Because the UHF element is radialless, it performs at peak efficiency without needing a large metallic ground plane, offering more versatile mounting options across your vehicle’s trunk, roof, or gutter mounts.
Built to handle modern high-power mobile transceivers, the Diamond SGM504 boasts a robust maximum power rating of 100 Watts FM (total cumulative input). It is precision-tuned to a nominal 50-ohm impedance and maintains a voltage standing wave ratio (VSWR) of less than 1.5:1 across its target amateur bands, ensuring maximum power transfer and protecting your transceiver’s power amplifier. The base of the whip is terminated with a standard, heavy-duty UHF Male connector (M-P / PL-259), allowing it to thread securely onto standard SO-239 mobile mounts, magnetic bases, or trunk-lid assemblies.
Key Features
- Ultra-Compact Dual-Band Performance: Seamlessly covers both the VHF (144 MHz) and UHF (430 MHz) amateur radio bands.
- Radialless UHF Design: Operates as a 1/2 wave radialless whip on 430 MHz, allowing for excellent performance without requiring a large vehicle ground plane.
- Focused UHF Gain: Delivers 2.15 dBi of gain on the 70 cm band to optimize signal propagation and reach distant repeaters.
- 100W Power Capacity: Safely handles up to 100 Watts of continuous FM RF power, making it fully compatible with high-power mobile rigs.
- Aerodynamic & Low-Profile: At just 40 cm in length and 160 g in weight, it easily clears low garages and reduces wind drag.
- Standard M-P (PL-259) Connection: Solid mechanical base threads natively into standard heavy-duty SO-239 vehicle mobile mounts or magnetic bases.
Technical Specifications
| Parameter | Specification |
|---|---|
| Brand | Diamond Antenna |
| Model Designation | SGM504 (Super Gainer Series) |
| Product Type | Dual-Band Mobile Whip Antenna |
| Frequency Bands Supported | 2 Meters (144 MHz) | 70 Centimeters (430 MHz) |
| Antenna Element Type |
144 MHz: 1/4 Wave 430 MHz: 1/2 Wave radialless |
| Antenna Gain Rating | 2.15 dBi (430 MHz) |
| Maximum Power Input | 100 Watts FM (Total cumulative) |
| Nominal Impedance | 50 Ohms |
| VSWR (Standing Wave Ratio) | Less than 1.5:1 |
| Base Connector Type | M-P (PL-259 / UHF Male) |
| Antenna Length | 0.4 m (40 cm) |
| Net Weight | 160 g |
Package Content
- 1x Diamond SGM504 Dual-Band Mobile Antenna Assembly
