W4GHS "Brute"

Model B-2

Performance Details

 

The "Brute" B-2 is a very ruggedly constructed vertical two-meter antenna designed and built to compete with "high end" vertical antennas in the repeater and base station market with a price that is competitive with many of the less expensive antennas. Its durability and performance should be second to none. Please read the construction details sheet for more information on the strength of the "Brute's" construction.

 

The performance of the "Brute" has been tested in the real world scenario of comparing performance against other well-known styles and types of antennas. Testing was done by using two stations in the simplex mode and with various distances of separation, elevation, antenna height and power level differences. I will review the testing later in this document but first I will cover some observations on systems of antenna evaluation.

 

The performance of any omni-directional antenna is a by-product of angle of radiation and gain. With a vertically polarized, omni-directional antenna the goal is usually a 360 degree uniform signal around the axis of the antenna and as little of the signal directed toward the sky as possible. Therefore, the lowest lobe needs to be directed along a path parallel with the ground or even have a slight down tilt.

 

The rating of "gain" and "angle of radiation" can be almost anything a manufacturer wants them to be based on the way that measurements are calculated. Gain for example can be rated as dBi (over an isotropic source, like the point of a pin if you could load it at 52 ohms) or you can rate gain over a wave dipole (dBd). With a given antenna all these values change with the increase or decrease of height above ground and the conductivity of the soil beneath the antenna.

 

For example at 5 feet above ground a wave ground plane with 20" radials mounted on a 45 degree angle has a 3.24 dBi gain in very poor soil and 3.03 dBi gain in very good soil. The angle of radiation in poor soil is 13 degrees but in very good soil the angle of radiation goes up to 37 degrees. If you raise that same antenna to 25 feet, it now has a 6.74 dbi gain in very poor soil and 5.79 dBi gain in very good soil. The wave vertical has a gain of less that .1 dBi difference from a wave vertical or a 5/8 wave vertical at 25 feet. Its angle of radiation drops to 3.5 degrees at 25 feet. Therefore gain and angle of radiation advertising can be very deceiving. The real test of antenna performance is how it compares with other antennas at the same location and time of day.

 

This is the method that I tested the "Brute" model B-2. In my first test, I was located 11.3 air miles from the receiving station. I was at an elevation of 2892 feet and the receiving station was at 2675 with some rolling hills between us. The receiving station was using a Brute B-2 in the attic at 10 feet above ground. All my test antennas were mounted 10 feet above ground. I was received with 5 watts at the same signal level as a wave vertical and a 5/8 wave vertical running 50 watts. This was a difference of 10 db but was the only test that I had this great of signal advantage.

 

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I next tested at an elevation of 3450 feet and 14.2 air miles separation between me and the receiving station was located at 2675 feet both with antennas at 10 feet above ground. In this test with 5 watts I had the same signal as the 5/8 wave vertical at 25 watts and a better signal than the wave ground plane at 25 watts. This represents about a 4 to 5 db gain.

 

In the third test, I was located about 9 air miles from the receiving station. There was a hill between the receiving station and me. In this test I was less than 1 db better than a wave vertical and was only equal to the 5/8 vertical. I feel, the reason for this was the hill blocking my lower lobe and canceling any advantage the Brute would have.

 

The last test that I ran was simplex between my station near Hillsville Virginia and another station at Christiansburg Virginia, a distance of about 50 miles. With 25 watts, I had a better signal with the Brute at 10 feet high than I had with a wave vertical (Ringo Ranger) at 55 watts. This was better than a 3 db advantage with the Brute.

 

The Brute is an excellent performer in a compact and strong package and I know that it will give excellent service in a harsh environment. In times of icing or freezing rain, you would not have to worry about continuity being bridged with your center conductor and radials. This would allow your repeater to operate without mismatches and heating your finals. It is also quick and easy to assemble, making it ideal for A.R.E.S. field operation. With the B2-F model, you can set it on a tabletop or the floor of an upper story room. The antenna is pre-tuned and should show less than 1.3 to 1 (Typically less than 1.2 to 1) anywhere on the amateur bands. You can use it on 140 MHz through 150 MHz at less than 1.5 to 1 SWR.

 

The performance of the Brute B-2 is very similar to a 5/4( 1 and 1/4 wave) EDZ (Extended Double Zepp) with an excellent 52 ohm match. The Brute has a 3.4 to 3.5 degree of radiation at 25 feet above ground and a little over 3 db gain over a half wave vertical for a dBi of 8.24 db in good soil. By purchasing a $600.00 antenna (not including a $200.00 motor freight bill) you could perhaps get a couple more dB gain over the "Brute" with the feed point of both antennas mounted at the same height. If both antennas were mounted at equal height at the tops of the antenna, the "Brute" feed point would be 15 feet higher and about all of the 2 db advantage would go away. With many of the long collinear antennas, in the winter, you would be contending with "Ice Bridges" between your center radiator and radials with the potential of destroying your finals. In high winds, the long commercial antennas are prone to "Wind Static" and the breaking of solder connections in the co-phasing stubs. The Brute has only one solder joint, at the point of connection with the SO-239. It is also very compact with almost no deflection in high winds.

 

Why choice the "Brute" over other available antennas? One of the big reasons is rugged construction. Antennas that sell at $495.00, advertise their heavy construction due to .125 wall thickness on the base. The Brute has a .375 wall thickness on its T-6 aircraft aluminum base, which is 3 times as thick.

 

But how do they compare in performance? The $495.00 advertises a 3dBd gain, which is 3 db over a wave dipole (not an isotropic source). In field test after field test the "Brute" shows a minimum of 3dBd over a wave vertical.

 

 

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What about performance comparisons with the long commercial grade antennas that have not only a low angle of radiation but may have 3 degrees or more "down tilt"? These antennas are expensive at $600.00 or more plus shipping, but offer some advantages when used in a high mountain top location (1000 ft or more above average terrain). They offer a little edge over an antenna that has a 3.4 degree angel of radiation in the range of 35 to a 50 mile radius from the repeater site. This advantage is reversed as you approach or go beyond the "line of sight" horizon. So, if you goal is long distance coverage as opposed to saturation cover near the base of a repeater site, the "Brute" is your antenna.

 

What about your $150.00 collinear design antennas that advertise 7db gain. For one thing, they cost more that the "Brute" (B-2 at $95.00 and the B-2F at $85.00). How do they rate their db gain? If you rate the "Brute" over an isotropic source at 25 feet above ground with soil conductivity being classed as good, the "Brute can claim a 8.24 db gain. But when rated over a wave vertical that gain becomes 3 dBd. If you compare performance at the feed point, how much of the gain is due to the long physical length of the collinear, some of these may be as much as 20 feet long above their feed point? If you raise the "Brute" 15 feet at the feed point to establish an equal height at the top of the two antennas the performance results would be very similar between the two antennas, when working distant stations. Many of these long collinear type antennas have a difficult time surviving a winter at higher elevations and wind can wreak them at sea level locations. On one model of the $150.00 collinear, they advertise a 2:1 SWR at 145 MHz, and 1.2:1 at 146.5 and 2:1 at 148 MHz. This is very narrow banded with a high SWR at each end of the voice portion of 2 meters. The "Brute in contrast will cover 10 MHz with an SWR of less than 1.5:1 and will cover the entire 2 meter band with an SWR of less than 1.3 to 1 (typically 1.2 to 1).

 

The choice is yours but for the money the "Brute" is hard to beat.