To the left you can see a hideous prototype in the background that STILL vastly outperformed the antenna's that are available retail in our area. but it was being duplicated in digital anyway so no loss.) (Admittedly, lengthening the whiskers on this design did caus me to lose one analog station entirely that wasnt broadcasting near 500mhz. The pictures can explain he rest of the construction, but this bad boy receives about 77% digtal signal strength from repeaters about 17 miles away, and takes one analog station from marginal to nearly perfect. The reflector is something called 'hardware cloth' strung across framing pieces from a window screen repair kit. The main structure of the antenna is plastic gutter drain.
CRE 8900 MODULATION ADJUSTMENT TV
rather than trying to half ass the entire TV frequency spectrum. Proof I think that antenna effectiveness can be greatly improved by catering to a specific frequency.
And this antenna did indeed outperform a previous antenna that I made with 10" element lengths, a 20% increase in digital signal strenth to be exact. To the left and above you can see the copper elements made from 10 guage wire at 11.2 inches long. To me it just looks like 4 dipoles with funky shaped elements stacked on top of one another, so thats the math I went with, and 11.2 inches they shall be! Granted, this is not a dipole we are building, but dipole math is easier, and more honestly I have no idea how the "bowtie" design should be calculated. the ideal length of a copper element to a half wave dipole to recieve 500mhz. In my area, all of the broadcasts are clustered around 500 mhz, which has a 1/2 wavelength of 23.6".
This is a great website that will tell you where the TV signals are coming from in your area, how strong they are, and what frequencies they are. If you havent yet, be sure to check out . And further, the antenna should be tailored to the specific broadcast frequencies in your area. Half of 14.3 is 7.125, CLOSE to 7"! So nearest I can tell, a 7" whisker length looks to be about right for a 1/4 wave dipole antenna on the VHF band. So t looks like 7" is a nice compromise for an antenna to be resonant on two different bands.Ĭonsidering that most tv broadcasts on the UHF band, it would seem to make much more sense to me to tailor the antenna for UHF. 95 to get a copper element length of 14.3". The center of the VHF band is about 195mhz, which has a 1/4 wavelength of about 15.1". So maybe this 7" number is a compromise to cover the VHF band as well?
CRE 8900 MODULATION ADJUSTMENT FREE
A 680mhz 1/2 wavelength is about 8.7" long in free space, and so a copper element half wave dipole should be about 8.3 inches long. The UHF frequency allocation for television is about 470 to 890 MHZ, so the center of this band is 680mhz. Most of the designs I could find for this antenna style included a 7" whisker length, with no explanation as to where this measurement came from. The antenna I describe here, made for about $20 in parts receives 5 channels in our area almost perfectly. I bought a rabbit ears antenna WITH a pre-amp at the hardware store. Why are we paying the satellite or cable people 100 bucks a month? Well if you can do without HBO, gve this a shot.
TV is supposed to be free, and now that the networks are broadcasting in digtal, the picture quality is perfect HDTV. This antenna is an excellent performer on the UHF frequencies. Below is a design I came up with for what is called either a "DB4" antenna or a "bowtie antenna" for TV reception.