Fibreglass antenna?

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Fibreglass antenna?

Postby Southwales » Mon Feb 05, 2018 1:20 am

Hi, this maybe a silly question but when an antenna is described as fibreglass, does that mean the antenna is inside a fibreglass tube for protection? And are they any good?, this one claims Receive frequency: 25-2000MHz, do the radials actually help or are they just a gimmick? https://damsu.co.uk/two-way-radio/anten ... neiVmenzMI
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Re: Fibreglass antenna?

Postby m0lsx » Mon Feb 05, 2018 9:27 am

Looking at the model number that is a Moonraker antenna. And their build quality & quality control is not great.
I once ordered three antennas off Moonraker. A white stick, which arrived with sky high SWR, a handheld whip which arrived with the base connector not connected to the radiator correctly & a mobile whip that worked as it should. So two out of three not working & having to be returned & replaced!!
A fibreglass antenna is just a white, (hopefully,) weatherproof tube over a thin piece of wire & the claims of it covering 25 to 2000 MHz on RX are just sales patter. On RX it's just a length of wire & would work on medium wave. It would work badly on Medium Wave, but it would work.
The radials are there to help it at it's designed TX frequencies & will make little or no difference away from TX.
These so called white stick antennas have what is called gain & the higher the alledged gain, the less efficient they are away from their designed TX frequencies. This is caused by the operating bandwidth, the band of low SWR, being much narrower (sharper) than on a antenna with low or no gain.
So for a wideband RX antenna the requirements are different to a specific band transceiver antenna.
I personally use a three band version of the white stick. Mainly because when I put the antenna up, I was using all three bands (2 meters, 6 meters & 70cm) as a radio amateur. Now I only use 6 meters, so keep thinking next time I swap the coax, maybe I should also change the antenna, as it is only used for RX now, as I prefer a horizontal antenna for 6 meters.
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