S Unit

1/4 Wave GP and Balums

Facts First 

 1 ) Coax is " unbalanced ".   In a perfect system RF flow along the outer part of the inner conductor and the inside of the shield.  

2) A dipole is a " balanced antenna " 

3) A 1/4 GP is an " unbalanced antenna " 

4) To prevent the transmission line from becoming a radiator  ( currents on the outside of the outer shield )  a balum should be used.  

5) Balums are required when going from an unbalanced transmission line to a balanced load ( antenna ) .  

6) A Balum ( RF Choke ) is nothing more then a high impedance  device to force currents to flow through the lower impedance load ( antenna ) 

I was amazed at the 30m,  40m and 17m ground mounted 1/4 vertical antennas that I recently built.   They match easy VSWRs all below 1.1 : 1 at the tuned frequency.     I didn't realize at the time why these antennas worked out so well but the whole unbalanced to unbalanced thing makes sense.  

Came across this cool little video that explains it rather well ....

 

New 1/4 GP for 17 Meters

Built a 1/4 Vertical Antenna with 4 tuned radials for 17meters.    Each element is 13' ,  trimmed the vert el to be around 12' to be the lowest VSWR 1.1:1 at 18.068 MHz.   I am running this through my Ameritron RCS 4 remote antenna switch.   On the switch is a 30 meter and 17 meter antennas a couple of dozen feet apart.  I was listening on 30 meters and observed a signal around S5 with the 17 meter antenna when I switched to the 30 meter antenna it went to S9.  The difference between S5 and S9 is a whopping 24 db...HOLY Smokes .   I expected a few dbs but not nearly.

In the video I am tuned to a 30 meter station at first I am using the 17 meter vertical then I switch to the 30 merter vert then  back to then repeat ending on the 30 meter antenna.




As soon as I tuned up the 17 meter GP I called SSB CW once only repeating my call 3 times then  a station in Washington State came back,  56 and a guy in FLA 59.   Needless to  say it works very well!

1/4 GP for 40 Meters

Put together a 40m GP Ground Mounted Vertical.   The vert elemenet is a 33' chunk of wire supported by a tree limb.  Started with 4 40' radials but soon learned that that wasn't the best plan.  I have read so much about the radials ... big debate was how many ,  8 sounds optimal but 4 is OK... not much gained going beyond 8 maybe a db or so.   Another thing was the length of the radials ... read that longer is better,  read that ground mounted antennas like that the radials dont make a whole lot of difference that the currents flow through the earth..yeah right!

My antenna is sitting on a gravel hill ...  maybe 18" of top soil.  So I have a lousy ground and the radials are going to come into play!     The 30 Meter 1/4 GP had a flat SWR and I cut both the vert element and radials the same 23' length.    I was  a little leery of the 39' radials for the 40 meter antenna ....

When I first fired up the new antenna it was resonate at 6.7 MHz with a VSWR of 1.6.     The 30 meter was almost flat when I first cut it.    Made the initial cut on the vert el to get the antenna optimized for 6.9 MHz then wondered what would happen if I started shortening the radials.  


 freq              initial     -1' radial         -1' radial         -3" vert el      -1' radial

6.6                 2                      1.9                   1.9             2.1                   2.1
6.7                 1.7                   1.6                   1.5             1.7                   1.7
6.8                 1.6                   1.5                   1.4             1.5                   1.4
6.9                 1.5                   1.5                   1.3             1.4                   1.3
7.0                 1.6                   1.5                   1.4             1.4                   1.25
7.1                 1.7                   1.5                   1.5             1.4                   1.3
7.2                 1.7                   1.7                   1.6             1.5                   1.4
7.3                 2                      1.9                   1.8             1.7                   1.6

So after the initial measurements I took 2' off the radials then 3" off the vert el then another foot off the radials .  Decided to keep on trimming to see how low will it go.

freq             -1' radial           -1' radial         -1' radial         -1'radial

6.6                  1.7                   1.8                   1.9                  2.1
6.8                  1.5                   1.5                   1.5                  1.6
6.9                  1.3                   1.3                   1.2                  1.2
7.0                  1.25                 1.2                   1.1                  1.05
7.1                  1.3                   1.2                   1.1                  1.05
7.2                  1.4                   1.3                   1.2                  1.1
7.3                  1.5                   1.5                   1.4                  1.3

So I trimmed 7' off the radials so they are around 33' and trimmed about a foot in total off the vert around 32' .

I am just trying to make the antennas as efficient as possible.












              

5MHz and an updated Freq/Bandwidth for Canada

Schedule I — Frequency Bands and Bandwidths for Use by Amateur Stations Operating in Canada and in Region 2

Item	Column I	Column II	Column III	Column IV
	Frequency Band	Maximum Bandwidth	Operating Provisions	Operator Qualifications
1	135.7-137.8 kHz	100 Hz	5.67A	B and 5, B/H, B&A
2	1.800-2.000 MHz	6 kHz		B and 5, B/H, B&A
3	3.500-4.000 MHz	6 kHz		B and 5, B/H, B&A
4	5.332 MHz	2.8 kHz	C21	B and 5, B/H, B&A
5	5.348 MHz	2.8 kHz	C21	B and 5, B/H, B&A
6	5.3585 MHz	2.8 kHz	C21	B and 5, B/H, B&A
7	5.373 MHz	2.8 kHz	C21	B and 5, B/H, B&A
8	5.405 MHz	2.8 kHz	C21	B and 5, B/H, B&A
9	7.000-7.300 MHz	6 kHz	5.142	B and 5, B/H, B&A
10	10.100-10.150 MHz	1 kHz	C6	B and 5, B/H, B&A
11	14.000-14.350 MHz	6 kHz		B and 5, B/H, B&A
12	18.068-18.168 MHz	6 kHz		B and 5, B/H, B&A
13	21.000-21.450 MHz	6 kHz		B and 5, B/H, B&A
14	24.890-24.990 MHz	6 kHz		B and 5, B/H, B&A
15	28.000-29.700 MHz	20 kHz		B and 5, B/H, B&A
16	50.000-54.000 MHz	30 kHz		B
17	144.000-148.000 MHz	30 kHz		B
18	219.000-220.000 MHz	100 kHz	C11	B
19	220.000-222.000 MHz	100 kHz	C11 – Exceptional circumstances only	B
20	222.000-225.000 MHz	100 kHz		B
21	430.000-450.000 MHz	12 MHz	*	B
22	902.000-928.000 MHz	12 MHz	*	B
23	1.240-1.300 GHz	Not specified	*	B
24	2.300-2.450 GHz	Not specified	*	B
25	3.300-3.500 GHz	Not specified	*	B
26	5.650-5.925 GHz	Not specified	*	B
27	10.000-10.500 GHz	Not specified	*	B
28	24.000-24.050 GHz	Not specified		B
29	24.050-24.250 GHz	Not specified	*	B
30	47.000-47.200 GHz	Not specified		B
31	76.000-77.500 GHz	Not specified	*	B
32	77.500-78.000 GHz	Not specified		B
33	78.000-81.000 GHz	Not specified	*	B
34	81.000-81.500 GHz	Not specified	5.561A	B
35	122.250-123.000 GHz	Not specified	*	B
36	134.000-136.000 GHz	Not specified		B
37	136.000-141.000 GHz	Not specified	*	B
38	241.000-248.000 GHz	Not specified	*	B
39	248.000-250.000 GHz	Not specified		B

Notes: In Column III, "*" means that transmissions shall not cause interference nor be protected from interference from stations licensed in other services operating in that band. Operating provisions defined below are excerpts from the Canadian Table of Frequency Allocations, which is amended from time to time. In Column IV, "B" means an Amateur Radio Operator Certificate with Basic Qualification, "B/H" means Basic with Honours (score of 80% or above), "5" means an Amateur Radio Operator Certificate with Morse Code (5 w.p.m.) Qualification, and "A" means an Amateur Radio Operator Certificate with an Advanced Qualification. C6 The use of the band 10 100-10 150 kHz by the amateur service in Canada is not in accordance with the international frequency allocations. Canadian amateur operations shall not cause interference to fixed service operations of other administrations and if such interference should occur, the amateur service may be required to cease operations. The amateur service in Canada may not claim protection from interference by the fixed service operations of other administrations. C11 In the band 219-220 MHz, the amateur service is permitted on a secondary basis. In the band 220‑222 MHz, the amateur service may be permitted in exceptional circumstances on a secondary basis to assist in disaster relief efforts. 5.67A Stations in the amateur service using frequencies in the band 135.7-137.8 kHz shall not exceed a maximum radiated power of 1 W (e.i.r.p.) and shall not cause harmful interference to stations of the radionavigation service operating in countries listed in No. 5.67. (WRC-07) 5.142 Until 29, March 2009, the use of the band 7 100-7 300 kHz in Region 2 by the amateur service shall not impose constraints on the broadcasting service intended for use within Region 1 and Region 3. After 29 March 2009 the use of the band 7 200-7 300 kHz in Region 2 by the amateur service shall not impose constraints on the broadcasting service intended for use within Region 1 and Region 3. (WRC-03) 5.561A The 81-81.5 GHz band is also allocated to the amateur and amateur-satellite services on a secondary basis. (WRC-2000) The following operating provision is not currently in the Canadian Table of Frequency Allocations, but will be included in the next revision of the document. C21 (CAN-14) Amateur service operators may transmit on the following five centre frequencies: 5332 kHz, 5348 kHz, 5358.5 kHz, 5373 kHz, and 5405 kHz. Amateur stations are allowed to operate with a maximum effective radiated power of 100 W PEP and are restricted to the following emission modes and designators: telephony (2K80J3E), data (2K80J2D), RTTY (60H0J2B) and CW (150HA1A). Transmissions may not occupy more than 2.8 kHz centred on these five frequencies. Such use is not in accordance with international frequency allocations. Canadian amateur operations shall not cause interference to fixed and mobile operations in Canada or in other countries and, if such interference occurs, the amateur service may be required to cease operations. The amateur service in Canada may not claim protection from interference by the fixed and mobile operations of other countries.

More 5/8 research ....

There are some big problems with the previous blog entry so as much as I really thought it would make a great antenna.  Here is another take ...

5⁄8-Wavelength verticals
Figure 7-14 shows the configuration for the 5⁄8-wavelength vertical antenna. Such an
antenna generally gives a lower angle of radiation than the more common quarterwavelength
radiator, so presumably it works better for long distance.
The radiator of this antenna is made from 0.5-in to 1.5-in aluminum tubing.
Again, remember that adjacent sizes fit together snugly to form longer sections.
The physical length of the 5⁄8-wavelength radiator is found from


Lft=585/FMhz or Lmeters=180/F Mhz


The radials are the usual quarter-wavelength, and are made of no. 12 or no. 14
copper wire. These lengths are found from:

Lft=246/FMHz

The feedpoint impedance of the 5⁄8-wavelength antenna is about 1600Ω, not a
good match for the ordinary coaxial cables that are routinely available on the amateur
market. Some form of impedance matching is needed.
One option is to use a broadbanded RF transformer. These transformers will
work throughout the HF spectrum, and match a wide variety of impedances to the
50-Ω standard system impedance.
Another option, especially for a single-band antenna, is to use a coaxial cable
impedance transformer, such as shown in Fig. 7-14. The transformer consists of two
sections of coaxial cable joined together, shown as L1 and L2 in Fig. 7-14. The
lengths are found from

L1 ft = 122/F MHz  

L2 ft = 30/F MHz

Or use a "Q section  "  L Meters =75/F MHz

5/8 Vertical for 30 Meters

A HIGH-PERFORMANCE 1-WIRE DX ANTENNA

By Gary Huff, K9AUB

We all would love to have a very high tower with an elaborate array of Yagi antennas to assist us in our pursuit of DX.  However, many of us have limited funds, and we can’t afford such elaborate equipment.  Indeed, some of us live in areas where towers are prohibited.  However, if you have a tall tree or other high support in your yard, don’t think that you can’t work DX with a simple wire antenna.  You can put that tree to work for you!

It is often said that the best simple antenna for DX is a vertical antenna.  This is true, but often a vertical is disappointing because it really doesn’t perform all that well.  However, there are verticals, and then there are VERTICALS!

Vertical antennas can be improved upon by making them higher (longer), and by installing a decent field of ground radials under the antenna.

The “standard” vertical for HF work is a ¼ wave vertical.  When placed over a decent set of ground radials, it will perform well for DX work (over 1000 miles).  It may not seem to be much of an improvement on shorter DX paths, out to 2000 – 4000 miles.  Beyond about 5000 miles, the ¼ wave vertical does begin to outperform a dipole.  By the time you get out to 6000-8000 miles, a ¼ wave vertical has a noticeable advantage over dipoles.  Still, they aren’t always the panacea for working DX that they are often described to be.

However, there are more verticals than just a simple ¼ wave vertical.  You can also lengthen them to a height of ½ wave, or 5/8 wave!  When you do this, their performance does improve by a noticeable amount, because their angle of radiation is lowered.  (There isn’t a lot of improvement to go beyond 5/8 wave.)

A ¼ wave vertical has approximately a 30 degree angle of radiation, which is an improvement over a dipole, because a dipole wastes so much radiation at higher angles.  For short-range communications, a higher angle of radiation is an advantage, which is why dipoles are superior for short-range work.  Still, a 30 degree angle of radiation is not ideal for DX work.  To achieve maximum performance over a long distance, we need to lower that angle of attack to an even lower angle.  Ideally, the best angle of attack is approximately 16 degrees.  Can we achieve that with a simple vertical antenna?  Well, in a word, yes.

A ½ wave vertical has a lowered angle of radiation of about 20 degrees, and displays slight gain over a ¼ wave vertical.  This is an improvement over a ¼ wave vertical!  However, the ½ wave vertical presents some significant problems with feeding it.  The bottom of a ½ wave vertical is at a very high impedance, high voltage point, and requires some carefully engineered matching networks to feed it.  Capacitors and inductors must be tuned to match the high impedance, and they must have high voltage ratings, since there are at least several thousand RF volts at the end of a ½ wave vertical.  This problem can be overcome by feeding the ½ wave vertical at the center, where it becomes simply a dipole antenna hung straight up and down.  If you can run the feedline at a 90 degree angle from the vertical wire, this may be a solution for you.

Can we improve on this vertical antenna?  Yes, we can!  If we lengthen the vertical antenna to 5/8 wave in length, the angle of radiation lowers to an ideal 16 degrees, making it perfect for DX performance!  And, the base of the 5/8 wave vertical can be fed with ordinary 52 ohm coax.  There is a slight amount of capacitive reactance at the base, and the “perfect” 5/8 wave vertical has a small amount of inductance in series with the base of the antenna, to tune out this reactance.  Fortunately, this isn’t a critical coil, and can be simply 6 or 8 turns of wire, with a diameter of about 2 “.  If you demand a perfect 1:1 match, you might want to wind a longer coil and then tap it 1 turn at a time until you find the perfect inductance to exactly match your antenna.  But, for practical applications, you can simply feed the antenna with coaxial cable, and you’ll get good performance.  If you use an antenna tuner, you’ll be just fine with this simple antenna.

Take a look at this graph, which shows the gain and angle of radiation for each type of vertical:

This 5/8 wave antenna also displays about 3 dB of gain over a ¼ wave vertical.  So, you get an effective increase in radiated power, AND it’s at the more ideal 16 degrees of radiation!  The effective performance can often be an actual improvement over a ¼ wave vertical by several S-units on long-distance paths!

How long should the antenna be?  Well, here’s where it gets interesting.  The formula for a 5/8 wave antenna is 585 / F (mHz).  This compares to the formula for a ¼ wave vertical, 234 / F (mHz), and the ½ wave vertical formula is 468 / F (mHz).

Let’s see… if we install a ¼ wave vertical for 40 meters CW, that’s approximately 33.4 feet.  If we want to install a 5/8 wave antenna for 17 meters (18.1 mHz), that length is 32.3 feet.  WAIT A MINUTE…. Those numbers are VERY close!  That means that a ¼ wave vertical for 40 meters can also be used unmodified for a 5/8 wave vertical for 17 meters!  You get two for one!  Nice!

But, we’re not finished.  Let’s look at what else such an antenna can do.  We all know that a 40 meter antenna can be used on its 3^rd harmonic, or 15 meters.  In actual practice, we usually discover that a 40 meter antenna isn’t really ideal for 15 meters.  For various reasons, the 40 meter antenna resonates very high in the 15 meter band, up at the top of – or outside - the phone end of the band.

Well, can we play with this antenna a bit and make it a better performer?  Well, of course we can!  Turns out that by making the 40 meter vertical slightly long so that it resonates at the very bottom of the band (7.000 mHz), the resonant spot on 15 meters drops down to the middle of the 15 meter phone band, about 21.3 mHz.  If we make the 40 meter vertical just slightly longer, making it match about 6.985 mHz, we still have an almost perfect 1:1 SWR on the very bottom of 40 meters CW, and that number rises to about 1.7:1 SWR at 7.300 mHz, the top of the 40 meter phone band.  Most modern transmitters with pi networks can easily match this antenna across the entire 40 meter band.  Or, we can use an antenna tuner.  This would call for a length of about 33.5 feet.

A 33.5 foot vertical will have a perfect 1:1 SWR on 15 meters with a resonance of close to 1:1 around 21.250 mHz.  It becomes a 3/2 wave length antenna, which means it will have a much lower angle of radiation, approximately 18 degrees, and it will have about 3 dB of gain on 15 meters.  This means it will be a “hot” performer on 15 meters, and can be matched across the 15 meter band with ease.

Now, can we squeeze more performance out of this 40 meter vertical?  Well, it’s only slightly longer than a 5/8 wave vertical for 17 meters, which ideally needs a 32.3 foot length.  The difference is small enough that, again, this antenna can be matched with ease on 17 meters!

So, summarizing, if we install a ¼ wave vertical for 40 meters, resonant at the bottom of the 40 meter CW band, we end up also with an excellent performing 5/8 wave vertical for 17 meters, AND a very decent performing ¾ wave vertical on 15 meters.  1 antenna, 3 bands!  And all it takes is one single vertical radiator of about 33’4” in height.

What shall we construct this vertical radiator from?  Well, we can install aluminum or steel tubing, install it over a base insulator (a champagne bottle works nicely here!), and add suitable guy wires.  That’s what you’ll need if you have no trees on your property.  But, if we have any mature trees on our property, then we almost certainly have a limb at least 34 feet or higher from the ground.  With a sling shot or casting rod, a rope can be shot over one of these tall limbs, and an ordinary piece of wire can be pulled up to vertical position.  A vertical wire will work just as well as a length of tubing.  Install an insulator at each end, and a short ground stake or ground anchor at the base to hold the bottom of the wire in place, and you’ve got your vertical radiator.

Now, the next important part of a vertical antenna is ground radials.  The books try to intimidate you into thinking that you need a ground field of 120 radials, or at least 60 radials if you want the antenna to work at all.  But is that true?  What if you only have room for 8 or 10 radials?  Will the antenna still perform?  In a word, yes.  The difference in performance between a vertical antenna with only 4 ground-mounted radials will be improved by about 1 S-unit if you proceed with the full 120 radials.  Hardly worth the effort for all but the most heroic installations.  In real life, 8 or 16 radials is perfectly adequate.  The difference between 16 radials and 120 radials is only a fraction of an S-unit.

How long should the radials be?  Well, ¼ wave on the lowest frequency you plan to use the antenna on is adequate, about 33 feet each.  These radials should be made of copper wire, if possible, but you can use galvanized steel (electric fence wire) if you’re on a budget.  The heavier the wire, the longer it will stand up to the elements.  Thin steel wire will rust out and be gone in a few years.  Thick copper wire (10 AWG) will last for many years.  Let your budget be your guide.

Whatever you use, the radials should all be connected at the base of the antenna to a ground ring, which can be as simple as a loop of heavy copper wire encircling the base of the antenna.  Solder each radial to the loop.  Use a heavy soldering gun to make the connection.

Is the length of the radials critical?  Well, actually not.  If your property line prohibits running a full ¼ wave radial out in each direction, don’t worry if you can only achieve part of this length.  Or, you can run the radial out to your property line, and then bend it to complete the length of the run.

Can the radials be longer than ¼ wave?  Yes, they can.  In fact, longer radials tend to give improved performance.  Feel free to run your radials out to the limits of your property line.  A 50 foot radial works better than a 33 foot radial, and a 100 foot radial works even better.  The reason that is true is that the radial is forming a capacitive coupling to the earth, and the longer wire improves that coupling out to a longer distance around the base of the antenna.

The radials may be buried a few inches below the surface, to keep them out of the reach of the lawn mower.  However, if you lay the radials out in late Fall, the snows and rain will bury your radials for you.  By Spring, they will have sunk slightly below the surface of the ground, and they will be safe.  Inspect the radials in the Spring:  if there are any high spots, go ahead and push them slightly into the ground while it’s still soft and muddy.  After a couple of years, you’ll never know the radials are there. 

What kind of wire can we use for the vertical?  It can be anything you have on hand, but for the vertical portion, it should be strong enough to stand up to Illinois ice, wind and snow storms.  Use a quality wire if you can, 14 gauge copper clad steel is perfect.  But, you can also use 12 or 14 gauge ordinary single-conductor house wire.  Don’t use 16 gauge hookup wire; it’s not sturdy enough to last more than about 1 season.  If it’s 16 gauge copperweld, that will work fine.

Can the wire be insulated?  Yes, but be aware that there is a slight Velocity Factor to insulated wire, which will make your antenna be very slightly shorter than bare copper wire.  There is no deterioration in performance with insulated wire, but you’ll probably have to trim your vertical radiator slightly to bring the antenna to resonance.

For the radials, use any wire you have on hand.  It can be bare or insulated.  For a cheap source of wire for radials, check with a contractor friend who is remodeling an old house or store.  Often, they have a lot of wire they’ve pulled out of the building, and if it’s not long enough, simply solder it end to end and use it for your radials.  If all else fails, buy some 14 or 16 gauge ignition wire from a farm store, where it is sold in 100 foot rolls very cheaply. 

What if your tree limb is just slightly too low, and you can’t stretch out the antenna as you’d like?  Well, you could add a loop of wire at the top of the antenna, which acts as a capacitive hat.  The larger the loop, the shorter the physical length of the antenna can be.  You’ll need to trim your antenna to its final length.  It’s wise to start out with your vertical radiator being slightly long, and then trim it slightly to bring it to resonance.  After you’ve got your length worked out, then solder everything in place.

Remember, the 585 / F (mHz) works for all other bands as well.  If you wanted a very high performance 40 meter vertical, you COULD erect a 5/8 wave vertical on 40 meters.  However, be aware that the length would be 585 / 7 = 83.5 feet.  That’s a pretty heroic vertical radiator in anyone’s book, but if you really want a super performing 40 meter vertical, you might investigate whether this would be a possibility for you.  And, if you can’t get all 83.5 feet to stand vertically, feel free to run it as an Inverted L, with as much of the wire as possible running vertically, then bend over the top and run the remaining wire over to another tree.  20 meters becomes much more practical:  41.7 feet is a practical length of wire if you have a tall tree with a high limb.  A 5/8 wave vertical on 20 meters will perform very similar to a 2-element beam.  For 10 meters, you would only need a vertical of 20.8 feet.

Give the 5/8 wave vertical a try if you want to work DX, but you just can’t afford a tower and beam.  You’ll be very pleasantly surprised at its performance.

40 Meter Wire Antennas

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40 Meter CW

Center Frequency:   7.025 Mhz  20.73 Mhz 3rd Harmonic
Halfwave in space is:  70.04 feet 47.62 coax|57.43 twinlead
Quarterwave in space is: 35.02 feet 23.81 coax|28.71 twinlead

Quarterwave Vertical is: 33.31 feet 39.22 foot ground radials
Five Eights wave Vertical is: 85.84 feet 33.31 foot ground plane
Three Quarter wave Vertical: 103.35 feet 16.65 foot eighthwave

Halfwave Dipole/Vertical is: 66.62 feet 33.31 one side.
Halfwave Reflector is:  69.95 feet 63.62 for Director
Low Mount Halfwave is:  65.20 feet 32.60 one side.
Halfwave Folded Dipole is: 65.77 feet 32.88 one side.
Halfwave Inverted V is:  69.04 feet 34.52 one side.
Colinear Array is:  136.65 feet 68.33 one side.
Extended Double Zepp is: 171.67 feet 85.84 one side.

Fullwave Quad Loop is:  145.20 feet 36.30 one side.
Reflector|Director:  152.46|138.66 38.11|34.67 one side.
Fullwave Delta Loop is:  145.20 feet 48.40 one side.
Reflector|Director:  152.46|138.66 50.82|46.22 one side.

Waves 1: 136.65 |1.5: 206.69 |2: 276.73 |2.5: 346.76 |3: 416.80 |4 : 556.87
Waves 5: 696.94 |6.0: 837.01 |7: 977.08 |8.0:1117.15 |9:1257.22 |10:1397.30

17 Meter Wire Antennas

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Center Frequency:  18.110 Mhz  53.45 Mhz 3rd Harmonic
Halfwave in space is:  27.17 feet 18.47 coax|22.28 twinlead
Quarterwave in space is: 13.58 feet  9.24 coax|11.14 twinlead

Quarterwave Vertical is: 12.92 feet 15.21 foot ground radials
Five Eights wave Vertical is: 33.30 feet 12.92 foot ground plane
Three Quarter wave Vertical: 40.09 feet  6.46 foot eighthwave

Halfwave Dipole/Vertical is: 25.84 feet 12.92 one side.
Halfwave Reflector is:  27.13 feet 24.68 for Director
Low Mount Halfwave is:  25.29 feet 12.64 one side.
Halfwave Folded Dipole is: 25.51 feet 12.76 one side.
Halfwave Inverted V is:  26.78 feet 13.39 one side.
Colinear Array is:  53.01 feet 26.50 one side.
Extended Double Zepp is: 66.59 feet 33.30 one side.

Fullwave Quad Loop is:  56.32 feet 14.08 one side.
Reflector|Director:  59.14|53.79 14.78|13.45 one side.
Fullwave Delta Loop is:  56.32 feet 18.77 one side.
Reflector|Director:  59.14|53.79 19.71|17.93 one side.

Waves 1:  53.01 |1.5:  80.18 |2: 107.34 |2.5: 134.51 |3: 161.68 |4 : 216.01
Waves 5: 270.35 |6.0: 324.68 |7: 379.02 |8.0: 433.35 |9: 487.69 |10: 542.02

Hard to believe that I still have this radio in the shack ....

Balun for my 14AVQ?

Giving some thought to Baluns,


Original article is here   http://www.hamuniverse.com/balun.html


Came across this guy ...

Rather simple ,  take 21' coax and wind it around anything and you have it .

Why a Balun  ...

A balun's purpose is to allow connecting a balanced, (e.g., a dipole or driven element) to an unbalanced line such as coax which is not balanced, thus the name, Balun. The 1:1 choke "balun" is not actually a balun. It's function is to help eliminate rf currents from flowing on the outside of coaxial cable using the principle of choke action. Another "name" for it is the air choke.

In transmitting antennas, this is accomplished by presenting a high impedance (resistance), to RF currents flowing outside the coax shield. This forces currents in each side of a driven elements to be equal. This is especially important in beam antennas because it prevents distortion of the beam's pattern caused by unequal currents in the driver(s). In a simple dipole, the balun (choke), assuresthat the dipole, and not the feed line, is doing the radiating!
When you connect center fed antennas, like dipoles, V's, triangles, yagis, rhombics, loops and so on, to coaxial cable, unless care is taken, it is not difficult to end up with feeder radiation. Not only can the loss in power be quite significant, but the radiation characteristics of the antenna system will also be seriously compromised.
In laymen's terms, it won't be what you are expecting from the pattern of your antenna.
As the feedline becomes part of the antenna, currents can flow from the line into the mains and on TV cables, metal masts and yagi booms, causing a variety of EMI problems  that can be very difficult to trace. Frequently these problems are simply due to unbalance - and the solution is the humble air choke.
If an antenna system is fed at center with a parallel conductor line (provided that correct installation procedures are followed) balance will be maintained, USING A BALUN, with currents in equal and opposite phase canceling each other out.
When the connection is to a coaxial cable, WITHOUT A BALUN, this cannot occur because currents flowing inside the cable from the connection to the inner conductor are separated from those flowing on the outside from the connection to the shield, and the result is unbalance causing feeder radiation. However, if the two electrical circuit elements (antenna and coaxial cable) are coupled using a balan, balance will be maintained.

30 Meter Ant #s

30 Meter Wire Antennas

---

This Band CW Only

Center Frequency:  10.120 Mhz  29.87 Mhz 3rd Harmonic
Halfwave in space is:  48.62 feet 33.06 coax|39.87 twinlead
Quarterwave in space is: 24.31 feet 16.53 coax|19.93 twinlead

Quarterwave Vertical is: 23.12 feet 27.23 foot ground radials
Five Eights wave Vertical is: 59.58 feet 23.12 foot ground plane
Three Quarter wave Vertical: 71.74 feet 11.56 foot eighthwave

Halfwave Dipole/Vertical is: 46.25 feet 23.12 one side.
Halfwave Reflector is:  48.56 feet 44.16 for Director
Low Mount Halfwave is:  45.26 feet 22.63 one side.
Halfwave Folded Dipole is: 45.65 feet 22.83 one side.
Halfwave Inverted V is:  47.92 feet 23.96 one side.
Colinear Array is:  94.86 feet 47.43 one side.
Extended Double Zepp is: 119.17 feet 59.58 one side.

Fullwave Quad Loop is:  100.79 feet 25.20 one side.
Reflector|Director:  105.83|96.25 26.46|24.06 one side.
Fullwave Delta Loop is:  100.79 feet 33.60 one side.
Reflector|Director:  105.83|96.25 35.28|32.08 one side.

Waves 1:  94.86 |1.5: 143.48 |2: 192.09 |2.5: 240.71 |3: 289.33 |4 : 386.56
Waves 5: 483.79 |6.0: 581.03 |7: 678.26 |8.0: 775.49 |9: 872.73 |10: 969.96

This is a shared band. Expect to find Commercial RTTY and FAX, especially Weather FAX transmissions on this band. Most international HAM signals will be found near 10.105, but Japanese stations frequently cluster around 10.130 Mhz.

Remote antenna sw

Its in the mail ...

I am going to run the existing 30 meter Vertical through this switcher then I am planning on adding a 30 meter dipole for comparison.   Not sure if I will do 2 more different 30 meter antennas but I do know one thing for sure its going to be really cool.  If this switch works out I am going to get the larger one with more inputs plus VHF/UHF capabilities for the top of the hill.