DB4 phase line material suggestions?

[Ihave3days]

I just made my first antenna to compliment the LCD tv I bought my best friend for his birthday (since he can't afford cable/satellite).

For ~$20, it works extremely well as he now receives 16 channels, compared to the 4 he received with an $80 amplified antenna I bought him last year.

I used 6 gauge bare copper for the whisker elements, & 12 gauge bare copper for the phase lines. The 12 gauge is sturdy enough that the crossovers should never touch, but I was wondering if anyone had a better suggestion for the next one I build?

I only had a week to learn everything I could & assemble the antenna by his birthday, but the whole experience has really gotten me interested in this sort of thing!

[GroundUrMast]

One of the primary reasons to build an antenna yourself is to save a bit of money (there are plenty of other reasons to be sure). 12 gauge copper is an excellent material. It's easy to obtain, easy to work with, fairly economical and has moderate strength.

Without going into a long explanation, length and spacing of the phase lines is important. When using 12 ga. to build phasing lines, the spacing should be about 1 3/8 inches.

The length of the element whiskers is shorter than ideal in several online plans. You may want to try starting at 10"... it's easier to shorten than lengthen.

Sounds like you did well.

[Ihave3days]

Originally Posted by GroundUrMast

One of the primary reasons to build an antenna yourself is to save a bit of money (there are plenty of other reasons to be sure). 12 gauge copper is an excellent material. It's easy to obtain, easy to work with, fairly economical and has moderate strength.

Without going into a long explanation, length and spacing of the phase lines is important. When using 12 ga. to build phasing lines, the spacing should be about 1 3/8 inches.

The length of the element whiskers is shorter than ideal in several online plans. You may want to try starting at 10"... it's easier to shorten than lengthen.

Sounds like you did well.

Thanks GroundUrMast!

I wanted to build it myself because he is a very hard-working (albeit very poor) construction worker, & I knew he would appreciate me taking the time & effort to build it on my own (I'm kind of a "white collar guy").

I used a piece of 1x3 instead of the often mentioned 2x4, so I could keep the phase lines about 1.5 inches apart. I used the 12 gauge bare copper because like you said, it was easy.

If I build another with say 10 gauge insulated copper, would that make a difference in the efficiency of the antenna?

I figure (& I have only been learning about this for a week so please correct me if I'm wrong), but the thicker wire should not only act as a better conductor, but it would be insulated at the crossovers, to make sure they don't touch & cause a short in the antenna.

I am also playing with the idea of a reflector screen, but that is a post for another day

[GroundUrMast]

...the thicker wire should ... act as a better conductor...

In theory, yes. In practice, lab grade meters won't see a significant difference if you substitute 10 ga. for 12 ga. If that's what you have available, use it.

Element lengths and spacing will have far greater effect on the frequencies the antenna will be 'receptive' to. A reflector will also be far more significant than the wire diameter. A reflector can help focus the sensitivity toward the front of the antenna.

If you are interested, look for material regarding wave propagation and develop you understanding of phase relationships. An understanding of how waves move across a medium like water will help you visualize how radio wave move along a conductor. Wikipedia is a great launch pad for finding material to read.

[Dave Loudin]

Please check your build against the plans here. This design evolved from the original online designs through modeling and testing. You can't do better. One note about construction: mounting the bowtie elements directly to wood can have an impact on performance. The plans at the site I linked to talks bout this.

If you're happy with what you've got, then that's fine. Have you checked what your friend might get using TVFool?