Topband: BOG height

[FZ Bruce]

 The Wave (BOG) antennas in Maine were very low frequency. The height
above ground in wavelength was low.
 Radio Corporation of America 1XAO here in Belfast was using 15 to 22
KHZ prior to 1924. The antenna length was 52,610 feet in length (just
under 10 Miles)
To develop a good front to back , and pattern a BOG needs to be close
to the ground in terms of wavelength.

As Guy K2AV said it does not behave like an above ground Beverage
antenna.

The Amateur Radio BOG is mis-named, should have been something like
WOG (wire on ground)

73
Bruce- K1FZ

	-----------------------------------------From: "K4SAV" 
To: topband at contesting.com
Cc: 
Sent: Saturday August 3 2019 9:44:11PM
Subject: Re: Topband: BOG height

 K2AV seem to be a storehouse of information. Thanks again Guy.

 One point, K2AV said:
 "If you model a real BOG, you find that beyond an ELECTRICAL half
wave ON
 THE WIRE, or two hundred something feet on 160, extending the BOG
wire will
 start to REVERSE the pattern."

 That never happened with my 366 ft BOG when it was lying on dead
grass 
 at an average of about 1.5 inches above the dirt. My tests comparing
a 
 250 ft BOG to a 366 ft one showed no significant front to back 
 difference. There were some pattern differences in other directions.

 I have never put a BOG directly on dirt so I can't say what happens 
 there. Measured data with the BOG 1.5 inches above the dirt does show

 that BOG gain drops about 6 dB right after a heavy rain or about the 
 same when covered by an inch of snow. Normally the gain of both the
250 
 and 366 ft BOGs were at about -17 dBi measured by comparison to
another 
 antenna that I know the gain of.

 I do know where the 250 ft recommended length for a 160 BOG came
from. 
 It came from NEC. I can make those same conclusions too if I only
look 
 at NEC data. I originally decided on 365 ft because NEC said it was 
 better than 250 ft. Subsequently I have lost confidence in NEC being 
 able to calculate BOG performance at any length. That was the impetus

 for my tests comparing 250 to 366 ft.

 K2AV also said:
 "A "beverage" ON the ground really is NOT a beverage."

 I agree that there is a lot of difference between a BOG and a
Beverage 
 above ground. At least that's the way we refer to them now but did
you 
 know that the antenna invented by Harold Beverage was a wire lying on

 the ground? Here is an excerpt from an interview with him:

 Beverage's words:
 "I invented the receiving antenna, the groundwave, the long waves
laid 
 on the ground. They were unidirectional, and nobody knew why. Others
— 
 the Navy — had used the ground waves, too. So I took a big heavy 
 receiver down the line and broke into some wires to see how the
signals 
 built up as it went towards the north and the static went down. Then 
 going the other way, the signal went down and the static came up.
Well, 
 I discovered that the reason that that antenna wire laying on the
ground 
 was unidirectional was the high losses. So that the static had built
up 
 to the northeast end and never got back down to the southwest end
into 
 the receiver. It was unidirectional just simply because of the losses
of 
 the wire laying on the ground. The idea then was we put stuff on
wires 
 at the northeast end. There was a resistor equal to the impedance of
the 
 antenna to make it unidirectional. You had but one wire I think."

 Jerry, K4SAV

 _________________
 Searchable Archives: http://www.contesting.com/_topband [1] - Topband
Reflector
 

Links:
------
[1] http://www.contesting.com/_topband