coils , rings , hairpins and gama matches . whats the differences ?

[BOOTY MONSTER]

coils , rings , hairpins and gama matches .....

whats the benefits and short commings of each over the others @ 27MHz. ?
is one better performing with beams rather than omni antennas ?
is one better performing with omnis rather than beams ?

whats the best/most efficent matching devise for 27 MHz. ? on a 1/4 wave ? on a 5/8 wave ?

 

[Moleculo]

OK, I'll take a stab at this. All of these matching methods are basically just different ways to accomplish the same thing (except in the 1/4 wave antenna). When you use a coil, you have to be a little careful how you design the coil so that your matching device can handle whatever power you're going to run through it. You also should design it with an eye toward minimize signal loss introduced from the coil. The tuning rings that the Imax use move closer and farther away from the Imax's tuning coil. There has been quite a bit of discussion about which impedance matching method (coil, hairpin or beta, or gamma) is the "best" and which ones introduce more loss than the others. I haven't personally done enough study or seen enough hard scientific documentation to give a hard, factual answer on that one. There are definately advantages to each method depending on what type of antenna you are building.

On a quarter wave antenna (or a half wave dipole-type) you don't need a matching system. In that case, the coil is there to allow you to shorten the antenna from the 1/4 wave length that it would normally be. When you do this, coil design becomes very important to minimize the losses that are introduced.

I hope that helps a little.

 

[BOOTY MONSTER]

i never thanked you for the comments moleculo .


thanks

 

[Marconi]

coils , rings , hairpins and gama matches .....

whats the benefits and short commings of each over the others @ 27MHz. ?
is one better performing with beams rather than omni antennas ?
is one better performing with omnis rather than beams ?

whats the best/most efficent matching devise for 27 MHz. ? on a 1/4 wave ? on a 5/8 wave ?

Hey BM, you probably read a lot about antennas I suspect. Don't you find it strange in our modern technological world all we seem to end up with in this regard is,

"...to be continued"

or

"...the answer to this question is beyond the scope of this article."

We often hear Ole Billy Bob's claim that one matcher works better than another. This is fine, but IMO if the real antenna Elmer's we read won't or can't, once-and-for-all, answer this question, and the history of antenna theory available, with all the applications, don't define these differences, so we can understand, then I'm not inclined to believe that Ole Billy Bob knows or can show us the differences either.

 

[RickC.]

I can tell you that hairpin matches are much easier to homebrew and adjust than gammas with no worries about RF voltage/capacitor issues. I've built both with yagis and honestly could not see any difference in the two in bandwidth or performance.

I suppose if I were interested in building a yagi with both horizontal and vertical elements I'd use gammas. Other than that, the physical construction would dictate which to use (insulated vs. grounded element, whether yagi/quad/delta loop, etc.).

Cebik was big proponent of hairpin matches for homebrewers, and there is good info there on the W4RNL site-- but you probably have already seen that, BM


Rick