Vertical Antenna

Using about 30 feet of RG6.
Making a vertical ground plane antenna for APRS.
Will be using about 40-45 watts.

The problem I see here is that ham radios are 50 ohm devices. So are the antennas. 144.39 is in the ham 2 meter band. Using 75 ohm cable may not work well. 75 ohm cable is used for TV operation.

2007-09-01 17:11:32 by Mc G.

This is the Zero-Five 43 feet multiband vertical antenna installed at my QTH. Sorry for the heavy breathing but the allergies were kicking when I ...

What loss can you automatically assume when working between a vertical and a horizontial polarized antenna?

3dB

2009-02-14 08:00:15 by Ron D.

5.1dBI Gain. Operates effectively on 6 through 20 Meter bands with a tuner, 10/11M without tuner.
24' Antenna in Three Easy to Assemble Sections
Includes U-Clamps to attach to optional mast pipe.
Handles 5000 Watts
Full 5/8 Wave Antenna

A vertical antenna is mounted atop a 40 ft pole. From a point on the level ground 78 feet from the base of the pole, the antenna subtends an angle of 10.7 degrees. Find the length of the antenna to the nearest tenth of a foot.

A) 20.6 feet B) -25.3 feet C) 33.2 feet D) 11.7 feet

Let:
a = angle subtended by the 40 ft pole.
h = height of the antenna

tan(a) = 40/78
a = arctan(40/78)
a = arctan(0.512820513)
a = 27.149681698 degrees

tan(a+10.7) = (40+h)/78
tan(27.15+10.7) = (40+h)/78
tan(27.15+10.7) * 78 = (40+h)
(tan(27.15+10.7) * 78) - 40 = h
(0.777069276 * 78) - 40 = h
60.611403567 - 40 = h
20.611403567 = h

Answer:
A) 20.6 feet



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2009-08-03 17:38:44 by __A_YAHOO_USER__

Works With Any CB Radio UK or USA
Newest Version Now 2400 Watts Maximum.
Weather Tight Indoor Outdoor Design
Use for AM, FM, USB, LSB, Radios.

I live in the Caribbean

Too bad, I have a ham radio tower in my back yard that's free for the taking. You're a bit too south for this. Sorry.

2008-07-23 07:39:57 by Antillean Maffia

Can pilots adjust the tilt angle of their WXR antenna while it’s (in operation) sweeping from side to side, in an effort to find the “core” of a storm? I have the impression that this is possible because of a seemingly great importance for awareness on the vertical profile the storm, since the weather radar beam naturally gives a horizontal (“slice”) profile. In an interesting way, this reminds me of a doctor using a CAT scanner...steering its beam, to draw a three-dimensional model of a patient’s affected body section. If the WXR’s beam is steerable, vertically by the pilot (while the radar set steers the beam horizontally), I’d like to know where the control for this (capability) is in the cockpit.

Yes, the tilt control is on the weather radar control panel. Some installations also have an auto-tilt feature. You are not so much trying to find the "core of the storm" as you are trying to determine what weather exists at your altitude and below (above if climbing, possibly, although the aircraft is already "tilted" upward; use of the tilt control would depend on the installation). Farther from the aircraft, at high altitude, you might paint a return which is not ground clutter but which disappears as it gets closer. This is usually due to the return being far below the aircraft. The dimensions of the beam pick it up beyond, say, 60 or 70 miles, but it is too far below the beam as it gets closer, even at an appropriate tilt. Remember the beam is not of a constant width/height for all distances from the aircraft.

2007-07-24 00:56:42 by wingless_pilot