Low VHF interference

rabbit73

SatelliteGuys Family
Jul 17, 2020
56
38
S.E. VA
Thats easy math.
Where does 5540 come from? Thank You.
Radio waves travel at the same speed as light waves, which is a constant called c:
The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its exact value is defined as 299792458 metres per second (approximately 300000 km/s, or 186000 mi/s).

The length of a halfwave dipole can be calculated in meters, feet or inches.
Mathematical Applications

λ (lambda) = c/freq

The length of the antenna is less than the free space length because of the "end effect."
Dipole Antenna Length: Calculation & Formula » Electronics Notes

The end effect is larger for VHF and UHF antennas because of the length to diameter ratio. Using the inches formula and the correction factor of 0.94:

5905 x 0.94 = 5550

Empirical tests show that 5540 works best in practical TV antennas:

5540 divided by 57 MHz = 97.2 inches
 
Last edited:

freeisforme

Thread Starter
SatelliteGuys Guru
Feb 21, 2017
136
26
south jersey
Radio waves travel at the same speed as light waves, which is a constant called c:
The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its exact value is defined as 299792458 metres per second (approximately 300000 km/s, or 186000 mi/s).

The length of a halfwave dipole can be calculated in meters, feet or inches.
Mathematical Applications

λ (lambda) = c/freq

The length of the antenna is less than the free space length because of the "end effect."
Dipole Antenna Length: Calculation & Formula » Electronics Notes

The end effect is larger for VHF and UHF antennas because of the length to diameter ratio. Using the inches formula and the correction factor of 0.94:

5905 x 0.94 = 5550

Empirical tests show that 5540 works best in practical TV antennas:

5540 divided by 57 MHz = 97.2 inches
Im good at math but, WOW:oops:. Good read.
 
  • Like
Reactions: rabbit73

freeisforme

Thread Starter
SatelliteGuys Guru
Feb 21, 2017
136
26
south jersey
I was waiting for channel master jointenna to be in stock, Came in stock Thursday, but they didnt update the LTE filter therefore i didn't buy it. When they update it, i will buy it. RF 2 does "come in, not watchable" more often then the twin lead. For now i may try different 2-ways and seen if one is better then the other. Thanks Rabbit73.
 
  • Like
Reactions: rabbit73

Users who are viewing this thread

Top