Aircraft can approach an antenna from any direction, so antennas need to be omni ("all") directional in the horizontal plane.
Early on, the easiest way to get omnidirectionality was to use vertical polarisation, and it's also the simplest kind of antenna - a simple rod or wire (of the right length) works just fine.
Subsequent antenna design has produced omnidirectional antennas with horizontal polarisation, but there are no significant advantages, and the design/construction is more complex than a vertical equivalent.
Yes.
A walkie-talkie refers to a portable radio. VHF range is usually 136 to 172 mhz and a portable will pick up if tuned to this range.
the high frequency, it is in VHF band.
If you're referring to commercial FM "music, news, and talk" broadcasts, the answer is 'No'.Those stations all transmit on carrier frequencies between 88 MHz and 108 MHz. Your VHF receivermost likely doesn't cover those frequencies.Even if it does overlap the commercial FM band, at the end of its dial, the VHF receiver won't deliveranything worth listening to.A). It's basically an AM receiver, not FM.B). It might deliver a recognizable voice from a narrowband FM signal, but it isn't designed toeven admit the comparatively wide-band commercial FM signals.
its a n channel jfet(field effect transistor) manufactured by Motorola
Almost all military transport and patrol aircraft use VHF.
Use LF or lower HF frequencies (rather than UHF or VHF), proper SWR tuning of antennas, radio amplification.
Valdis V. Liepa has written: 'Numerical approach for predicting radiation patterns of HF-VHF antennas over irregular terrain' -- subject(s): Antennas, Numerical calculations, Radio, Computer programs
C. S. Gledhill has written: 'VHF line techniques' -- subject(s): Wave guides, Microwaves, Antennas (Electronics)
If you are in a boat the frequency is 156.8 Mhz, also known as channel 16. For an aircraft emergency the VHF frequency is 243.0 Mhz.
The CB antenna is made for a limited band of frequencies and the VHF is a wide band antenna made for higher freqs. A CB antenna will not make a good tv antenna. A CB ant. is mounted on the vertical and tv ants. are mounted horiz. in the USA. VHF antennas are much smaller as they are for higher frequencies. Usually, they have many elements (rods) and will go from long in the back to short in the front. Certain CB antennas (beams) are mounted horizontally, but all of the elements are roughly the same length - and about twice as long as a VHF antenna. The elements on a horizontal CB antenna are roughly 18 feet from end to end.
The actual numbers are not as important as the knowledge that generally speaking, the larger the antenna the more gain it will have. Three other main factors are the Distance from the transmitting antennas are from your location and the Height of your antenna above the ground and what Obstructions there might be between the two antennas.
Because a VHF broadcast theoretically could reach thousands of people ! Additionally, if it's (for example) a marine or aircraft emergency, there are specific emergency channels, which are monitored 24/7 by professional people.
Line of sight communication is in the VHF and higher frequencies of the RF spectrum where the wavelength is to short to pass over structures and hills, the transmitter and receiver antennas must be in line of site
Because a VHF broadcast theoretically could reach thousands of people ! Additionally, if it's (for example) a marine or aircraft emergency, there are specific emergency channels, which are monitored 24/7 by professional people.
R. D. C. Thoday has written: 'A reflector unit for a 500 kW HF balanced screened feeder' 'Antennas for portable VHF-FM receivers'
You need a VHF radio antenna, a VHF radio receiver and of course a station broadcasting on the VHF frequency.