question: fiberglass VHF antenna

caltexflanc · Dec 14, 2015

WesK said:
Just to be clear, "Digital" is a brand of antenna, not a type or technology. They are built the same as any other VHF antenna. They seem to be of high quality but the technology is the same. They won't work any better.

1) the name derives from their roots making antennas for Motorola when the shift from analog to digital cellular was taking place.

2) No, they are not all made the same. I once witnessed an antenna dissection exercise when an offshore service company was bidding out a contract. The Digital had more robust internal parts and construction. Also, they tune each VHF antenna to be optimized and "centered" on 16. The Morads were the most rugged and the company went with a combination of them and the Digitals.

FlyWright · Dec 14, 2015

TDunn said:
The sailboat antenna is also acceptable because it is up high. Since VHF is line of sight, higher means longer range. For example my antenna on my sailboat is 50' above the water at its base.

Larry M said:
The 36" antenna is 3 dB vs the 8' is 6 dB.

...An antenna’s dB rating (or antenna gain) indicates the apparent increase in transmitting power due to its ability to focus energy...A gain increase of 3dB means a doubling of signal strength: 6dB is a fourfold increase, and 9dB is an eightfold increase. The actual watts transmitted doesn’t increase; it’s just that the power is concentrated, much like a reflector on a flashlight, in a more concentrated beam. Therefore, a radio with a 6dB antenna will sound like it has a larger transmitter than the same radio with a 3dB antenna...

Great points.

Antenna quality, coax quality, connector quality, antenna length/efficiency and antenna height are all important factors in maximizing range of a given radio. Transmitter power also comes into play. Most marine radios are very capable and transmitters of 15W or above should perform well with a proper installation.

I had some old, itchy antennas that got replaced after I decided against painting. Nothing wrong with that approach if they're working well. A quality antenna is not that much more expensive than a cheapo. The expensive part can be shipping, so ship free to a local store for pickup if you have that option.

rwidman · Dec 14, 2015

caltexflanc said:
1) the name derives from their roots making antennas for Motorola when the shift from analog to digital cellular was taking place.

2) No, they are not all made the same. I once witnessed an antenna dissection exercise when an offshore service company was bidding out a contract. The Digital had more robust internal parts and construction. Also, they tune each VHF antenna to be optimized and "centered" on 16. The Morads were the most rugged and the company went with a combination of them and the Digitals.

The name "Digital" fools some people into thinking they are somehow a more advanced technology. They are not.

The technology is the same as any other VHF antenna. It's possible that some models are more "robust" than some models of other brands. I suspect dollar for dollar, they are all about the same. Performance is the same as well.

caltexflanc · Dec 14, 2015

WesK said:
The name "Digital" fools some people into thinking they are somehow a more advanced technology. They are not.

The technology is the same as any other VHF antenna. It's possible that some models are more "robust" than some models of other brands. I suspect dollar for dollar, they are all about the same. Performance is the same as well.

They still make cell phone antennas, BTW. I suppose they could have changed their name after years in business to avoid angering you about "fooling" people.
You may suspect what you like, but I saw an actual test and unmasking what lay below the fiberglass (or aluminum in the case of the Morads). Probably had nothing to do with the tests I saw, but not long afterwards Shakespeare introduced a "premium" line of antennas.

psneeld · Dec 14, 2015

Wow...read up from manufacturer sites and independent info...too much borderline info here from my experience using and installing VHFs over 2 careers.

Power is way more important sometimes over height...especially with a lot of traffic or signal loss/interference.

Just my practical over theory experience talking.....

FlyWright · Dec 14, 2015

psneeld said:
Power is way more important sometimes over height...especially with a lot of traffic or signal loss/interference.

Power only helps with half of the function of a VHF transceiver...the transmit side. Receiving VHF signals is passive but receiver sensitivity matters. Both functions, transmit and receive, require line of sight (with minor exceptions) and are affected the other factors I cited.

In my job, we did years of certification of transmitters and receivers for communication and navigation in the FAA. When the FAA went to the NextGen comm radios, there was great hesitation among the old timers with the reduced power consumption and transmitter power. I conducted many hours of real world in flight testing over flat land, mountains and water in a variety of weather conditions near Santa Barbara, CA and confirmed that the performance met or exceeded that of the older, more powerful radios. Even the old time controllers and airway facilities techs were impressed and pleased.

psneeld · Dec 14, 2015

FlyWright said:
Power only helps with half of the function of a VHF transceiver...the transmit side. Receiving VHF signals is passive but receiver sensitivity matters. Both functions, transmit and receive, require line of sight (with minor exceptions) and are affected the other factors I cited.

In my job, we did years of certification of transmitters and receivers for communication and navigation in the FAA. When the FAA went to the NextGen comm radios, there was great hesitation among the old timers with the reduced power consumption and transmitter power. I conducted many hours of real world in flight testing over flat land, mountains and water in a variety of weather conditions near Santa Barbara, CA and confirmed that the performance met or exceeded that of the older, more powerful radios. Even the old time controllers and airway facilities techs were impressed and pleased.

I should have been more clear...the higher gain antennas can mean the difference in decent comms or not...not the power of the radio itself.

With no antenna, the most powerful or sensitive radio is useless...sorta..

question: fiberglass VHF antenna

caltexflanc

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