# Low VHF interference (1 Viewer)

#### rabbit73

##### SatelliteGuys Family
Rabbit73: How do you calculate the length of a folded dipole using 14AWG? Thank you.
It would be pretty much the same as with twinlead.

Channel 2 is 54 to 60 MHz; center freq is 57 MHz
5540 divided by 57 = 97 inches

• freeisforme

#### freeisforme

##### SatelliteGuys Guru
It would be pretty much the same as with twinlead.

Channel 2 is 54 to 60 MHz; center freq is 57 MHz
5540 divided by 57 = 97 inches
Thats easy math.
Where does 5540 come from? Thank You.

#### rabbit73

##### SatelliteGuys Family
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:
• c-spand, freeisforme, Tower Guy and 1 other person

#### navychop

##### Member of the Month - July 2014!
Pub Member / Supporter
And I thought I understood this.
Thanks.

• Mister B

#### freeisforme

##### SatelliteGuys Guru
sorry for the long delay i didnt get email. if i did i deleted by mistake.

#### freeisforme

##### SatelliteGuys Guru
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 . Good read.

• rabbit73

#### freeisforme

##### SatelliteGuys Guru
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.

• rabbit73

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