Linked Questions

19 votes
1 answer
5k views

How does moving a feedpoint off-center in a dipole affect the resonant frequency and resistive load?

Specifically, I understand that OCF dipoles change the SWR, but does it do this via reactance or resistance, or both?
Bill - K5WL's user avatar
  • 1,194
4 votes
3 answers
2k views

Suggestions for HF antenna for occasional use on my sailboat

I have had a license since I was a kid, but have not touched anything ham radio related in years. I have been thinking about diving back in and combining it with my sailing. I'm looking for thoughts ...
Jim Archer's user avatar
2 votes
2 answers
2k views

Yagi: split or solid driven element?

Short question: What are the advantages and disadvantages of using gamma (solid element) or beta (split element) matching a yagi? Long question: A while ago I built a coil loaded yagi for the 20M ...
hjf's user avatar
  • 1,199
1 vote
2 answers
2k views

Trying to identify and understand this antenna design - ground independent dual band vertical

This is the insides of a common dual band antenna 2m/70cm, made by diamond or nagoya. its generally labelled as: 1/2 wave radialless (144MHz), 2 x 5/8 wave radialless (430MHz) Its meant to be ground ...
Hayden Thring's user avatar
1 vote
2 answers
4k views

How to make a loop antenna for HF?

While researching this answer, I came across information that indicates that a many good Low Frequency/ Very Low Frequency antennas are loops, with high directionality and good overall characteristics....
PearsonArtPhoto's user avatar
1 vote
1 answer
2k views

How does a gamma match on a dipole work as a balun?

I have a resonant half wave dipole which is one continuous length and not separated in the middle, fed using a gamma match, and with the braid of the coax joined to the exact electrical center of the ...
Andrew's user avatar
  • 3,685
5 votes
2 answers
1k views

How to adapt commercial VHF yagi for 2 meter amateur use?

I recently acquired a Decibel 3-element VHF Yagi that was formerly in commercial service. I connected my MFJ-259B antenna analyzer to the antenna and found its minimum SWR at 155 MHz. I have not ...
Aurelia Peters's user avatar
2 votes
1 answer
2k views

Is it possible to determine if I'm adjusting gamma match in correct direction with an SWR meter and if yes, how?

I've recently obtained a Quad Loop antenna for 2 m and 70 cm that's fed through gamma match, as shown in the picture: The shorter metal bars are connected to the hot side of the BNC, while the longer ...
AndrejaKo's user avatar
  • 2,893
2 votes
1 answer
2k views

Balun and impedance matching suggestions for dipole antenna

I'm a newbie who is attempting to build a half-wave dipole antenna that will be located in the rudder of a sailplane. 123.3 MHz is the most important frequency to me, although it's reasonable to ...
Chris Young's user avatar
1 vote
2 answers
801 views

Multi-part question. correct length of rg-8x coax to connect 2 meter HT to 50 ohm yagi

What it the optimal number of wave lengths of RG-8X coax to connect my Icom IC V80 HT to a 50 ohm Jetstream JTBM270 Yagi (3 elements 2m/5 elements 70cm)? Odd or even number thereof? Will running the ...
Marvin L. Steinhagen's user avatar
1 vote
1 answer
771 views

How to assemble an antenna (impedance matching methods)

I got the following plans off Martin E. Meserve's website. How do I go about assembling the antenna once I have the elements and boom? What is the impedance of the driven element? Do I need baluns ...
metropolis's user avatar
2 votes
2 answers
393 views

Balance of gamma / delta match

A center fed dipole, with equal arm lengths, is a balanced device. If it is fed using a gamma match - does it change (the system) to be unbalanced?
Jan Hus's user avatar
  • 167
2 votes
1 answer
503 views

Will these wires affect antenna performance negitavely?

We moved into a new house, and I noticed these wires sticking up for some sort of tent thing for shade. •I tested the wires to the 3rd prong in the outlet, and it showed a DC dead short to ground. •...
Skyler 440's user avatar
  • 7,600
3 votes
2 answers
242 views

VHF Balancing, necessary? Methods?

This is a question about power dissipated due to radiation and ohmic heating caused by common mode current in the coaxial shielding, specifically at VHF frequencies. When a balanced antenna (such as a ...
elplatt's user avatar
  • 160
2 votes
2 answers
231 views

Is there any difference in the voltage and current distribution for a half wave dipole fed in the middle, or fed with a gamma match?

Is there any difference in the voltage (potential difference wrt center) and current (rate of flow of electrons) distribution for a half wave dipole fed in the middle (dipole cut in the middle,) or ...
Andrew's user avatar
  • 3,685