Frequency Wavelength

[MarioMania]

Without going off-topic on the other thread, I'll start one

I seen Videos on YouTue about people have like Part 15 FM Broadcast Antennas about putting on a Frequency for a Best Reception

I didn't know about it's the sameway for picking up FM Reception on a Radio

I have different kinds of Radio with the Antenna extends at Different Lengths

Like I'm on 106.1 FM

Some Wavelength are Full, 3/4, 5/8, 1/2, 1/4, 1/8 What does that mean?

Tecsun PL-310ET Antenna is 21 inches long
Tecsun R-9700DX Antenna is 32 inches Long

 

[KC8UOK]

Without going off-topic on the other thread, I'll start one

I seen Videos on YouTue about people have like Part 15 FM Broadcast Antennas about putting on a Frequency for a Best Reception

I didn't know about it's the sameway for picking up FM Reception on a Radio

I have different kinds of Radio with the Antenna extends at Different Lengths

Like I'm on 106.1 FM

Some Wavelength are Full, 3/4, 5/8, 1/2, 1/4, 1/8 What does that mean?

Tecsun PL-310ET Antenna is 21 inches long
Tecsun R-9700DX Antenna is 32 inches Long

Formula:
Wavelength (in meters) = 300 ÷ Frequency (MHz)
So for 106.1 MHz:
300 ÷ 106.1 ≈ 2.83 meters
That means the full wavelength is:
2.83 meters (about 111 inches)
Now here are the common fractions of that wavelength:
Full wave (1λ) = 2.83 m ≈ 111 in
1/2 wave = 1.41 m ≈ 55.5 in
1/4 wave = 0.71 m ≈ 27.7 in
1/8 wave = 0.35 m ≈ 13.8 in
So for 106.1 FM, a quarter-wave antenna would be right around 27–28 inches, which is why many FM whips are roughly that length.

 

[KeithE4]

Without going off-topic on the other thread, I'll start one

I seen Videos on YouTue about people have like Part 15 FM Broadcast Antennas about putting on a Frequency for a Best Reception

You're limited on FM to 250 mV/m field strength regardless of what frequency you're using. This is equivalent to 11 nanowatts ERP into a dipole. In reality, you're better off connecting your transmitter to a 50 ohm dummy load to start, then check your range. If you can hear it a block away, you're probably running too much power. But the FCC isn't overly concerned about that as long as you aren't interfering with licensed stations (for example, if you have a local on 97.9, don't use 97.7 or 98.1) and are not trying to compete with them.

Take all YouTube videos with a semitruck load of Sodium Chloride. Same goes for FM transmitters being sold on Amazon. Especially the latter. Most of them are 100% illegal (1 watt or more power output) unless the antenna is removed and a dummy load is connected. Dummy loads do radiate a bit, even though they're not supposed to. But don't leave the antenna connector open. You will burn out the transmitter for a lack of a matched load.

I didn't know about it's the sameway for picking up FM Reception on a Radio

I have different kinds of Radio with the Antenna extends at Different Lengths

That doesn't matter much. If you can get the stations you like, don't worry about it. If not, you either have a lousy radio or need an external antenna.

Like I'm on 106.1 FM

Frequency is all but irrelevant for FM antennas, as long as the radio covers the whole band (all do). Even a cheap whip on a portable radio will have enough bandwidth to cover the band with little to no matching loss.

Some Wavelength are Full, 3/4, 5/8, 1/2, 1/4, 1/8 What does that mean?

Buy yourself an ARRL Handbook or Antenna Book (used ones from decades past are OK; theory hasn't changed) and read about how antennas work in terms of wavelength. It's too complicated to get into here.

Tecsun PL-310ET Antenna is 21 inches long
Tecsun R-9700DX Antenna is 32 inches Long

They're probably matched to the radios so they should work fine. For shortwave, an external antenna will be necessary. Even a long piece of wire will be an improvement.

 

[KC8UOK]

For shortwave, an external antenna will be necessary. Even a long piece of wire will be an improvement.

Very slight depending on the house. I have a long wire going out my window and only the powerhouses come in. Best bet is as far from the house as possible. Run coax outside for at least 10-15 feet.

 

[KeithE4]

Very slight depending on the house. I have a long wire going out my window and only the powerhouses come in. Best bet is as far from the house as possible. Run coax outside for at least 10-15 feet.

That's why I use a 40 foot End Fed Random Wire with a 9:1 unun as my ham antenna. It's fed with 100 feet of RG8X and installed in my back yard, about 30 feet from the noise generators in my house. Even with the mismatches, I do well on 40-10 meters with my in-shack (but not in-rig) tuner. With 1/4 wavelength radials, one for each ham band, it works fine.

 

[KC8UOK]

That's why I use a 40 foot End Fed Random Wire with a 9:1 unun as my ham antenna. It's fed with 100 feet of RG8X and installed in my back yard, about 30 feet from the noise generators in my house.

Impossible to do for me. I'm cursed by the HOA I'm in. My ham antenna is a pie plate magmount 3 foot off the ground. It works for local repeaters but anything fringe is a no go

 

[KeithE4]

OK, your talking 2 meters, and I'm talking HF, specifically 40-10 meters. I haven't owned a 2 meter rig since mine was stolen out of my van in 1996. Here in Phoenix, there are a couple 2 meter repeaters that are active, but not anywhere near the activity of the 1970s.

I'm not in an HOA, fortunately, but am restricted by the FAA to a maximum height of 20 feet above ground, being in the Falcon Field flight path. At least my ground is 135 feet above and 2 miles NE of the runway, so I can still get out well.

 

[KC8UOK]

Here in Phoenix, there are a couple 2 meter repeaters that are active, but not anywhere near the activity of the 1970s.

Same here unfortunately. Used to be pretty good even a few years ago.

 

[MarioMania]

Thanks Guys for the Info

Bear with me, I'm slow to learning Stuff