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Call 0345 2300 599The OptiBeam OB8-4M is a powerful, compact, and innovative 8 element four-band HF Yagi covering the classic 40m, 20m, 15m, and 10m amateur bands.
It is designed to deliver serious multi-band performance from a single antenna system, using a single 50 ohm coax feedline and a trapless design. With two integrated high-performance Moxon rectangular beams, the OB8-4M offers strong gain, excellent front-to-back performance, and an efficient mechanical layout for operators who want high performance without moving to a much larger full-size multi-band array.
On 40m, the OB8-4M uses the advantages of a 2 element loaded Moxon-Yagi system. On 20m, a full-size 2 element Moxon provides excellent gain and a superb radiation pattern with very high front-to-back performance. The 15m section uses two active fully resonant elements, additionally supported by the 10m director at the front of the array. On 10m, the beam/director combination provides gain and front-to-back values approaching those of a 3 element full-size beam, helped by the positive contribution of the 15m elements behind it.
With a 6.1m boom, 10.52m maximum element length, and 6.12m turning radius, the OB8-4M is a strong choice for fixed-station operators who want capable directional performance across four of the most popular HF bands.
Key Features
- 8 element four-band HF Yagi
- Covers 40m, 20m, 15m, and 10m
- Trapless design
- Single 50 ohm coax feedline
- Integrated high-performance Moxon rectangular beam design
- 2 element loaded Moxon-Yagi style performance on 40m
- Full-size 2 element Moxon performance on 20m
- Enhanced 15m performance with support from the 10m director
- Strong 10m gain and front-to-back performance
- Excellent multi-band DX and contesting capability
- 6.1m boom length
- 6.12m turning radius
- 50kg antenna weight
- Suitable for serious fixed-station HF installations
Band Performance
| Band | Gain dBd | Gain dBi | Front-to-Back Ratio |
|---|---|---|---|
| 40m | 3.5dBd | 10.7dBi | 18dB |
| 20m | 4.2dBd | 11.4dBi | 25dB |
| 15m | 4.4dBd | 11.6dBi | 20dB |
| 10m | 4.9dBd | 12.1dBi | 28dB |
VSWR Performance
| Band | Frequency Points | VSWR |
| 40m general setting | 7.00 / 7.05 / 7.10 / 7.30MHz | 1.6 / 1.15 / 1.3 / 1.9 |
| 40m USA phone setting | 7.15 / 7.20 / 7.30MHz | 1.5 / 1.15 / 1.4 |
| 20m | 14.00 / 14.18 / 14.35MHz | 1.5 / 1.1 / 1.4 |
| 15m | 21.00 / 21.25 / 21.45MHz | 1.3 / 1.1 / 1.4 |
| 10m | 28.00 / 28.50 / 29.00MHz | 1.6 / 1.15 / 1.7 |
Specifications
| Specification | Details |
| Brand | OptiBeam |
| Model | OB8-4M |
| Product type | 8 element four-band HF Yagi |
| Antenna type | Directional antenna |
| Design | Yagi / Moxon multi-band system |
| Supported bands | 40m / 20m / 15m / 10m |
| Number of elements | 8 |
| Active elements | 2 / 2 / 2-3 / 2-3 |
| Feedline | 1 x 50 ohm coax |
| Maximum element length | 10.52m |
| Boom length | 6.1m |
| Turning radius | 6.12m |
| Wind load at 130km/h | 970N |
| Wind surface area | 1.20 sq m / 13.0 sq ft |
| Weight | 50kg |
Typical Uses
- Multi-band HF DXing
- HF contesting
- Fixed-station operation
- Operators wanting 40m, 20m, 15m, and 10m coverage from one beam
- Stations needing a compact high-performance four-band Yagi
- Permanent mast or tower installations
- Directional HF operation with a single coax feedline
Installation Notes
The OB8-4M is designed for fixed installation on a suitable mast or tower. Please ensure that your mast, tower, rotator, mounting hardware, and support structure are suitable for the antenna’s weight, turning radius, maximum element length, boom length, and wind load.
As with any HF Yagi, final performance will depend on installation height, surrounding structures, feedline quality, grounding, and correct assembly.
Important Note
This listing is for the OptiBeam OB8-4M antenna only. Mast, rotator, coaxial cable, mounting hardware, and other station accessories are not included unless stated otherwise.
Please check that your installation site, rotator, and support structure are suitable before ordering.
Shipping:
We have several shipping options for our products, including next-day and Saturday/Sunday delivery for certain items. Please see these options at checkout.
Returns:
If you have any equipment that needs to be returned to Martin Lynch & Sons, please fill out the form below:
Upon receipt of goods you have 14 days to return goods however the goods must be returned in original packaging and care must have been taken with the goods you wish to return. Under distance selling regulations you are not entitled to any refund on carriage charges or modification charges made at your request. Large items cannot be returned if they have been assembled, unless faulty.
Warranty Terms and Conditions
Outside of the 14 faulty return period, returned items cannot be accepted, unless covered by manufacturer's warranty. We will repair as much as possible on site however in exceptional circumstances products may have to be returned to the manufacturer of distributor.
For repairs/replacements under manufacturer’s warranty for any item please download a ML&S return form from the link above and return to ML&S with the faulty product.
International Warranty information
Warranty service for items we sell is available in the U.K. only, unless otherwise noted. It is your responsibility to pay freight for returned items to the U.K. and back to you for desired warranty coverage. All of our NEW products come with a minimum 12 month warranty, (Yaesu & Icom 24 months), with up to 90 days on second-hand equipment. Items returned for service must state "returned goods for repair" on the return air waybill or U.K. import customs duties apply and will be added to your invoice. For more info about returning items please contact our customer help desk, [email protected]