Sirio GPA 66-108MHz 1/4 Wave Ground Plane Base Antenna
SKU Part Number: SIRIO-GPA-66-108
The Sirio GPA 66-108 is a tunable 1/4 wave ground plane base antenna covering 66-108MHz. Designed for base station service, the GPA 66-108 provides...
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£39.95
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The Sirio GPA 66-108 is a tunable 1/4 wave ground plane base antenna covering 66-108MHz.

Designed for base station service, the GPA 66-108 provides omnidirectional vertical performance across the low VHF range. It is suitable for applications within its supported frequency range where a compact, robust, mast-mounted ground plane antenna is required.

The antenna is made from non-corrosive aluminium and assembled on a strong die-cast base for easy, secure installation and reliable outdoor performance. Frequency adjustment is carried out using the supplied tuning diagram.

The GPA 66-108 is fitted with a UHF female SO-239 connector and is designed for mounting on masts from 35-40mm (1.38-1.57in) in diameter.

Key Features

  • 1/4 wave ground plane base antenna
  • Tunable across 66-108MHz
  • Omnidirectional 360° H-plane radiation
  • Linear vertical polarisation
  • 50 ohm unbalanced feed
  • 0dBd / 2.14dBi gain
  • VSWR less than 1.2:1 at resonant frequency
  • 500W CW maximum power handling
  • UHF female SO-239 connector
  • Non-corrosive aluminium construction
  • Strong die-cast base
  • Stainless steel, chromed brass, nylon, and aluminium materials
  • Suitable for 35-40mm (1.38-1.57in) mast mounting

Typical Uses

  • Low VHF base station installations
  • 66-108MHz applications where authorised
  • 4m band installations where correctly tuned and permitted
  • Fixed monitoring and communications setups
  • General omnidirectional VHF coverage
  • Mast-mounted base antenna installations

Electrical Data

Specification Details
Antenna type 1/4 wave ground plane
Frequency range 66-108MHz, tunable by diagram
Impedance 50 ohms unbalanced
Radiation, H-plane 360° omnidirectional
Radiation, E-plane Beamwidth at -3dB: 86°
Radiation angle 0°
Polarisation Vertical
Gain 0dBd / 2.14dBi
Bandwidth at VSWR 2:1 6.5MHz at 66MHz
VSWR at resonant frequency Less than 1.2:1
Maximum power 500W CW
Feed system / position Direct / centre
Connector UHF female SO-239

Mechanical Data

Specification Details
Materials Aluminium, chromed brass, nylon, stainless steel
Wind load 54N at 150km/h
Wind resistance 150km/h (93mph)
Wind surface 0.05 sq m
Height Approx. 1930mm (1.93m / 6.33ft)
Radial length Approx. 1080mm (1.08m / 3.54ft)
Weight Approx. 700g (1.54lb)
Mounting mast diameter 35-40mm (1.38-1.57in)

Installation Notes

The GPA 66-108 must be tuned for the required operating frequency using the supplied tuning diagram.

As with any base antenna, final performance will depend on installation height, mast position, surrounding structures, grounding, feedline quality, and correct assembly.

Shipping & Delivery

We offer UK and international delivery services, including next working day and selected weekend options for eligible orders. Available services, prices and estimated delivery times are displayed at checkout.

Delivery Information

Delivery options depend on the parcel's size, weight, contents and destination. Express and weekend services are subject to availability and cut-off times. Oversized or exceptionally heavy items may require a specialist delivery quotation.

Returns & Cancellations

To arrange a return, please contact ML&S or complete our returns form. You may also exercise your statutory right to cancel by email or another clear statement, without completing the form.

Changed Your Mind?

Under the Consumer Contracts Regulations 2013, most purchases made online or by telephone can be cancelled within 14 days of receipt.

You must notify us of your cancellation within this period and return the goods within a further 14 days.

Please handle all goods with care. Returned items must be in a resaleable condition, complete with their original packaging, and all supplied accessories.

You may inspect goods as you would in a shop. Handling beyond what is necessary to inspect them may result in a lawful deduction for diminished value.

Exceptions

Modified Equipment & Reversal Charges

Additional return conditions may apply to equipment modified at the customer's request, including wideband transmit or receive modifications.

ML&S may charge a reasonable fee to reverse physical modifications and restore the equipment to its original factory specification. Any such charge will be agreed in advance and deducted from your refund.

 

Custom-Made Cable Assemblies

Coaxial cable assemblies manufactured to a customer's specifications are excluded from the 14-day return policy and are non-refundable unless faulty.

 

Software & Labour Charges

Labour and modification charges requested by the customer are non-refundable once the work has been completed.

Computer software may only be returned under the 14-day return policy if it remains sealed and unopened.

Return Postage Charges

Customers are responsible for the direct cost of returning unwanted or incorrectly ordered goods, where permitted by law. You may arrange your own suitable return postage or use one of our optional prepaid services.

Standard Parcels

Royal Mail Return Label

£5.95

Per parcel

For eligible standard-sized parcels, subject to Royal Mail restrictions. Free collection included.

Larger Parcels

DPD Return Label

£7.95

Per parcel

For larger or heavier parcels and any shipments with batteries.

Collection Service

DPD Collection

£25.00

Per parcel

Available upon request for eligible addresses, subject to availability.

Prepaid return charges will be confirmed before booking and deducted from your refund.

These prices apply to eligible UK mainland returns. Oversized items, specialist products and returns from other destinations may require a separate quotation. Estimated return costs will be disclosed before purchase.

Faulty or Incorrectly Supplied Goods

Return postage charges do not apply to faulty, damaged or incorrectly supplied goods returned under statutory rights. ML&S will arrange a free return in these circumstances.

Refunds

Refunds are processed without undue delay following receipt and inspection of returned goods, and no later than 14 days after we receive goods returned under statutory cancellation rights.

Refunds will be issued to the original payment method. Any prepaid return postage charges or lawful deductions for diminished value will be itemised.

Warranty Terms & Conditions

New Equipment Warranty

Minimum 2-Year Warranty

All new products supplied by ML&S carry a minimum two-year warranty against manufacturing defects, excluding batteries, which are covered by separate warranty terms.

Some manufacturers provide extended warranties, such as the three-year warranty available on eligible Yaesu equipment. Any additional coverage is subject to the manufacturer's terms and conditions.

Our workshop may assess and repair faulty equipment on site or refer it to the manufacturer or an authorised service centre where necessary.

Warranty exclusions may include batteries, normal wear and tear, accidental damage, misuse and unauthorised modifications, as specified in the applicable warranty terms.

All warranties are provided in addition to your statutory consumer rights against ML&S, which are not limited by the warranty period.

International Returns & Warranty

Unless otherwise stated, ML&S warranty servicing is carried out in the UK. International customers must contact us before returning goods to confirm shipping and customs requirements.

International customers are responsible for return postage unless the goods are faulty and ML&S has been notified within a reasonable time.

ML&S accepts no responsibility for additional charges resulting from incorrectly completed customs documentation. Any additional duties charged to ML&S as a result will be billed to the customer before return of the goods.

Need Help With a Return?

Our team can assist with returns, postage arrangements, modifications and warranty claims.

Nothing in these terms excludes or limits your statutory consumer rights.