The 5/8 and .64 debate!

[Hamin' X]

the antennas under discussion are described as 5/8 wave and .64 wavelength and designed to be operated in at or near resonant condition in the cb band. by virtue of that the feedline predominantly used is 50 ohm coaxial cable. the radio equipment used is designed to operate optimumly into a 50 ohm purely resistive load and don't include atu's as standard equipment.

if you want to talk about 80 meter dipoles that can operate multiple amateur bands when used with a transmatch or am broadcast stations then start another thread.

Actually, I would like to show that a 40 meter dipole can be used on 80 and only lose less <5% efficiency. But you are correct, I have wandered off topic and will return this thread to it's regularly scheduled programming.

:arrow: Is too in phase, or it won't radiate

Rich

 

[freecell]

"Is too in phase, or it won't "

now watch me change the subject and invalidate your claim.

phased antenna arrays that are fed with transformers in which one leg leads or lags the other by any number of degrees (out of phase) utilizes constructive pattern interference and n slit diffraction to alter the radiation pattern of the combined antennas. this technique is used to steer the radiation patterns of multi-element phased arrays.

the array is out of phase and yet it radiates well and in the direction/s that we chose. now you see that when the application changes it can make a statement like this totally without merit. all i did was change the subject. lol.

thanks, Hamin' X.

 

[Hamin' X]

I just installed a DB-408 on a commercial, UHF repeater, last weekend, so am familiar with phased arrays. However, my statement still remains true, as I was referring to radiation from a single element. All radiation from each individual element in a phased array, is in phase. It is the out of phase relationship, between the different elements, that determines the signal pattern.

We're still off topic, but it is interesting. Bet we could use up a lot of napkins, while having coffee.

Later, Rich

 

[Toll_Free]

"Is too in phase, or it won't "

now watch me change the subject and invalidate your claim.

phased antenna arrays that are fed with transformers in which one leg leads or lags the other by any number of degrees (out of phase) utilizes constructive pattern interference and n slit diffraction to alter the radiation pattern of the combined antennas. this technique is used to steer the radiation patterns of multi-element phased arrays.

the array is out of phase and yet it radiates well and in the direction/s that we chose. now you see that when the application changes it can make a statement like this totally without merit. all i did was change the subject. lol.

thanks, Hamin' X.

The problem is, you're now talking about phased arrays (which, by definition, feed their MULTIPLE elements out of phase with each other), not a single (monopole) element.

--Toll_Free

 

[freecell]

"which, by definition, feed their MULTIPLE elements out of phase with each other."

incorrect. a phased array can be fed either in-phase or out of phase according to the results desired. the pair of antennas used in the common dual antenna system on 11 meters ARE FED IN-PHASE, which means simply that the CURRENTS induced by the applied voltage reach their maximum values, flowing in the same direction at the same instant. the phase relationship is controlled by the spacing between the elements and the configuration of the associated feedline used to couple them. while both have an effect on the amplitude of the current induced the effects are not identical. for this discussion the term "phase" has the same meaning when used in connection with the CURRENTS flowing IN antenna elements as it does in ordinary circuit work. two CURRENTS are IN-PHASE when they reach their maximum values, flowing in the same direction at the same instant.

this discussion will be continued in the forum linked to below.

 

[rfoverlord]

out of phase won't radiate.
I know this statement to be false, more than half of the people on here are out of phase yet radiate some pretty informative post. 73 keep up the great info exchange

 

[Master Chief]

You can change the length of phasing cables between two active elements and actually STEER the radiation pattern!

In the HAM world, its about steering the main lobes. In the BROADCAST world, its about steering the NULLS!

I've seen it done as i'm sure QRN has too. Of course we are talking about BIG arrays!

 

[W5LZ]

Master Chief,
And, depending on when you were active, I'll bet you've seen one or two really big arrays (compared to the freq used) that were steered by phasing networks - lol. Most were painted grey...
- 'Doc

PS - And if I'm not mistaken, those arrays could be 'split' for seperate directional coverage, had power outputs that CB'ers don't even dream about (well, the sane(?) ones anyway), and from my absolutely "imaginary" experience, used TWTs to start with then switched to solid state devices.
[Before you ask, I was never in the militery, never outside of conus, never on a boat longer than 15 feet, and as stated a number of times, don't know what the @#$$ I'm talking about, never made M.C. cuz I didn't have a 'bug' and hate boolian logic!]
Can't spell either...

 

[Toll_Free]

Master Chief,
And, depending on when you were active, I'll bet you've seen one or two really big arrays (compared to the freq used) that were steered by phasing networks - lol. Most were painted grey...
- 'Doc

PS - And if I'm not mistaken, those arrays could be 'split' for seperate directional coverage, had power outputs that CB'ers don't even dream about (well, the sane(?) ones anyway), and from my absolutely "imaginary" experience, used TWTs to start with then switched to solid state devices.
[Before you ask, I was never in the militery, never outside of conus, never on a boat longer than 15 feet, and as stated a number of times, don't know what the @#$$ I'm talking about, never made M.C. cuz I didn't have a 'bug' and hate boolian logic!]
Can't spell either...

Having grown up in San Diego, I can attest to a small station the USN had on top of Chollas Heights...

ELF, used MASSIVE towers (each "leg" was larger than the biggest tower BASE I have seen at ANY amateur or CB station), and the power output was, well, amazing.

The 'coax' they used (hardline actually) was larger than my leg. Chollas lake was located about a quarter mile away.... Supposedly to cool the 'tubes' in the pa.

Funny thing, now the station is gone... They tore it down to make for military housing, then decided to close the bases it covered. SUCKS! But, there are a LOT of disfigured fish laying in and around that lake.

Every once in a while, I noticed, we lost ALL radio signals into and out of the area, as well. Can't say it was due to the .mil firing that array up, but ....... What else would do that?

--Toll_Free

 

[W5LZ]

Toll_Free,
Hey, it's California! What else do you need to say?
- 'Doc

 

[fatdude1]

the name of the radio staion was elf it was NAVRADTRANSFAC

On 21 July 1914 the Navy purchased about 75 acres for the facility. The purpose of the station was to provide reliable radio communication with the fleet at sea, as well as other shore radio stations in the Naval Communications System. The construction of the three towers, each 660 feet high, started in February 1915, and completed on January 26, 1916. Each of the self-supporting towers supported a nearly invisible triatic wire antenna array that was used for low-frequency transmissions. The facility was commissioned on January 26, 1917. When it was operational, the station broadcast its signals at 200,000 watts, making it for a time the most powerful transmitter in the world.

thanks goes to global security .org for the above statement

 

[Hamin' X]

ELF~Extremely Low Frequency

Rich

 

[fatdude1]

ok my bad should have known that one. :?






i fixed my above post thanks Hamin X

 

[Beetle]

Drop by Google Earth and take a look at Exmouth, Western Australia, then move north, all the way out to the end of that peninsula. Naval Communications Station Harold E. Holt. Nice antenna array: one hexagonal wire about 0.8 mile long on each of the six sides. This surrounds another hexagon with sides "only" about half a mile!

Coordinates: 21 degrees, 48' 58.94" South; 114 degrees, 09' 57.61" East.

If you don't have Google Earth, use Google Maps. It's slower, but it works pretty well.

 

[Master Chief]

Chollas Heights