VHF Antenna

VHF Antenna saat ini kurang digunakan...Klo di Indonesia, kita taunya kanal VHF digunakan untuk TV TVRI. Dan Kualitas gambar yang ada tak sebagus dari UHF TV.

Kanal VHF dari 30MHz sampai 300MHz, dengan range frekuensi tersebut maka dimensi antenna lebih besar di bandingkan kepada UHF ke atas. Karena dilihat dari pangjang gelombang dari frekeunsi VHF lebih besar dari panjang gelombang UHF.

Pada Umumunya VHF antenna yang kita aplikasikan tempo dulu (bahkan mungkin saja ) sekarang masih ada seperti di bawah ini :

Dari antenna Tersebut, kita hanya dapat kanal frequency TVRI saja. Jikalau ada yang menangkap signal UHF mungkin saja bandfrequency antenna nya melebar saja, atau melenceng tidak sesuai spek.

Read More

UHF Antenna

UHF antenna disini kebanyakan diaplikasikan kepada TV antenna. Masyarakat pada umumnya mengenal UHF Antenna sebagai TV Antenna, padahal UHF antenna secara pembagian frequency tidak hanya untuk aplikasi TV Antenna saja.

Namun juga, UHF antenna masuk kedalam aplikasi Operator Telekomunikasi. Range Frequency UHF Antenna dari 400 MHz sampai 4000 MHz.

Dari range UHF tersebut banyak sekali aplikasi dari UHF Antenna. Sedangkan untuk UHF Antenna yang aplikasi TV Antenna hanya 400 MHz sampai 800 MHz.

 

Read More

UHF Bands Frequency

The first UHF band is located at 406 MHz to 420 MHz and is designated for Federal
usage. The second band is located at 450 MHz to 470 MHz and is designated for non-Federal usage. The last band, from 470 MHz to 512 MHz, shares spectrum with UHF television channels 14 through 20 in a few major urban areas. Channels in all three
UHF bands are 25 kHz wide. The propagation range in the UHF band is even less than that found in the VHF high-band; however, the radio signals easily reflect off hills and buildings, so dead areas are generally very small.

1. 700 MHz Band
New bands from 764 MHz to 776 MHz and 794 MHz to 806 MHz have been proposed by the FCC. These new channels would be converted from TV channels 63–64 and 68–69 to Public Safety use. The channels would be either narrowband for voice plus low-speed data or wideband (up to 150 kHz) for high-speed data.

2. 800/900 MHz Band
The portion of the radio spectrum from 806 MHz to 940 MHz is apportioned among many services, including cellular telephone, paging, nonpublic safety, and conventional
and trunked public safety. Federal Government users, however, have no authorizations in this spectrum. Channels for public safety are reserved in blocks that are
generally 25 kHz wide. These blocks reside in several locations within this portion of the radio spectrum. These radio signals reflect off hills, buildings, vehicles, etc., well enough that dead areas are nearly nonexistent. The propagation range for this band is shorter than for the UHF bands.

Read More

VHF Band Frequency

There are two band frequency:

1. VHF Low-Band
This band is located at 25 MHz to 50 MHz and generally uses channels 20 kHz wide. Communications ranges can be the greatest in this band; however, the radio signals do
not reflect effectively off hills, buildings, and other surfaces, so there may be dead spots within the general area of coverage of a base station. These frequencies, especially at the lower end of the band, are subject to ionospheric “skip,” which can carry a signal very long distances (and cause interference to other users). This band also has the highest level of ambient noise, which reduces the performance of receivers
operating in this band compared to other, higher frequency-bands.

2. VHF High-Band
This band is located at 150 MHz to 174 MHz and uses channels 25 kHz or
30 kHz wide. Adjacent channels may be separated by 12.5 kHz to 15 kHz for
geographically separated systems. Radio signals in this band have a shorter
propagation range, experience less noise than those in the VHF low-band, and are not
subject to ionospheric “skip.” Diffraction over hills and around other obstacles reduces dead areas of coverage.

Read More