Base Station Antenna Question

[Borage257]

On 10/18/2022 at 12:35 AM, flashover52 said:

Curious if anyone has tried a GMRS tuned yagi, such as the one Tram Browning sells?

I made one (see "Rate my Yagi" post). Using my 5W HT with the antenna height being about 7', I was able to get into some repeaters about 40 miles away. Standing on my roof (antenna height 31'), I was able to do 75 miles. 

I imagine a better made yagi would do even better. 

[Borage257]

1 hour ago, KAF6045 said:

Not really -- VHF & UHF (and microwaves) are used for satellite control BECAUSE the wavelengths PASS THROUGH the ionosphere with minimal effect. 6m skip is somewhat rare except at solar peak, and 6m is considered in the "VHF 'octave'" (30-300MHz, HF is 3-30MHz, UHF 300-3000MHz).

HF frequencies, OTOH, are affected by ionization, and are why many AM broadcast stations have to reduce power or change antenna directionality at sunset/sunrise -- to avoid having nighttime propagation affecting other stations on the same frequency (and the few clear-channel stations that are allowed full power at night now cover multiple states rather than just a few counties).

 

If you are seeing a difference it is more likely due to industrial and business activity generating increased background RF noise which swamps out low powered GMRS signals. Though I will concede I encountered something that I think was a tropospheric ducting event a few months back. https://en.wikipedia.org/wiki/Tropospheric_propagation

There is something to tropospheric ducting on UHF ( at least that's what the local old timers say). Some days before storms, I've been able to talk to repeaters 75-100 miles away on my rubberducky antenna and HT. Before I got my antenna up high, there were repeaters I couldn't get into except in the late evening and very early morning. 

I am in a relatively flat are out near East TX.

[KAF6045]

9 hours ago, Borage257 said:

There is something to tropospheric ducting on UHF ( at least that's what the local old timers say). Some days before storms, I've been able to talk to repeaters 75-100 miles away on my rubberducky antenna and HT. Before I got my antenna up high, there were repeaters I couldn't get into except in the late evening and very early morning.

In the old days, before everyone ended up with a $$$ cable feeding their TVs, weird weather could relay TV signals way beyond the target area. I recall our rooftop antenna (about 25ft above local ground level) picking up stations from Detroit or even the Canada side of the border... FROM GRAND RAPIDS AREA! 175-200miles.

 

[WRUK662]

On 10/7/2022 at 3:07 PM, Sshannon said:

The reason I looked at Comet was because I followed a rabbit trail that started here. I read some posts here from some highly respected people like Marc Spaz that gave high marks to the Comet CX-333 tri-band antenna. 

So then I searched for a review of the antenna and found a comparison test of the Ed Fong antenna to the cx-333. 
The Comet did a couple dB better, which is significant.

Then the guy who did the tests contacted Ed Fong to get his comments. Mr. Fong spoke very highly of the Comet antenna and also of the Comet company and how accurately they advertise their products. 

 

I just ordered the CX-333 to upgrade my Comet GP-3.  The GP-3 works well but there is some 1.25m activity in my area plus the CX-333 has better gain.

My GMRS radio, the Wouxun KG-UV9GX, is still on backorder.  Nearest GMRS repeater is about 4 miles distant.

WRUK662
WA7HPK

[AdmiralCochrane]

On 10/24/2022 at 2:08 PM, WRUS537 said:

I never knew this, learned something, thank you

 

On 10/24/2022 at 12:50 PM, KAF6045 said:

why many AM broadcast stations have to reduce power or change antenna directionality at sunset/sunrise -- to avoid having nighttime propagation affecting other stations on the same frequency (and the few clear-channel stations that are allowed full power at night now cover multiple states rather than just a few counties).

 

WABC in NYC can be received as far south as Maryland and Virginia many nights, but not at all during the day. 

[KAF6045]

15 hours ago, AdmiralCochrane said:

 

WABC in NYC can be received as far south as Maryland and Virginia many nights, but not at all during the day. 

And is one of the stated clear-channel stations per https://en.wikipedia.org/wiki/Clear-channel_station#List_of_all_clear-channel_stations

[BearFamily]

https://www.sws.bom.gov.au/Educational/1/3/6#:~:text=VHF and UHF Communications 

 

That gives a very basic answer. Remember the "sun lit" hemisphere is when it's daylight.