5/8 wave 2 meter antenna
ok so i have asked questions about making a Wilson Lil Will 11 meter antenna into a 2 meter antenna and was advised against it.
so now i am thinking of trying to make one out of my old 102 whip i have laying around.
since i don't need it i figured i would get on and ask about doing this.
my question is what would be the total length i would need for it to be a 5/8 wave antenna.
i am terrible at math thats why i am here asking the question.
any help would be greatly appreciated.
i have a mag mount and also a few bee hive mounts in stock already.
yes i am being cheap, i don't have the extra cash right now to buy another antenna so i figured why not reuse what i have that i am no longer using.
thanks and 73`s
Its gonna need to be around 48''
thanks.. i have seen around the net that most are around the 54" but i also noticed they have about 4 inches of wrapped copper wire on the base of the antenna and waned to make sure that i didnt need to be actually longer than 54" since i will be using just a S.S. Whip
Originally Posted by KB1PRQ
A 5/8 whip will require a matching coil at the base in order to get a 50 ohm impedance.
See this thread for more information.
I have an interesting VoCom antenna bot long ago at Dayton, where it was demonstrated. There is a coil above the BNC, then a telescoping whip. I can't see into the coil, but think there is a cap feeding a tap, as is common with a 5/8.
With the whip collapsed, it is a matched 1/4 wave, TOTAL overall length of 8".
When extended, it is a matched 5/8, TOTAL overall length of 48".
Makes comparison easy,and the 5/8 works Great!
Don't know if VoCom is still in business.
TOM K8ERV Montrose Colo
The same coil that matches a 5/8 will also serve as a loading coil for a shortened antenna. A typical base "loaded" 5/8 antenna for 2M has a coil of wire that is about 9" long, in a 1.25 inch coil, IOW, several turns.
Originally Posted by K8ERV
That coil makes the antenna look like a 3/4 wave electrical length, which matches to 50 ohms pretty well. The coil doesn't radiate much, so the 5/8 wave section does the actual radiation.
That coil can be used as a 6M loading coil (discussed elsewhere), or a 2M loading coil for a short (8" or so) antenna. The short antenna will be inefficient, but work OK, for what it is.
Consider keeping the 102" whip as is.
When you advance to HF mobile, you will need a whip. Screwdriver antenna makers usually do not ship a whip with them and expect you to provide your own. The 102" whips are becoming more difficult to obtain locally, depending on where you live.
A 102" whip may be cut down for a 1/4 wave 6 meter antenna, (or 5/8 2 meter) but will be a little stiffer than desired for mobile, depending on the individual whip.
A 1/4 wave whip for 2 meters is more practical from a size and performance standpoint and will work about as well as the 5/8 wave. They may be made from fence wire, welding rod, soft copper home wiring, etc. Construction sites routinely throw away 20 inch lengths of #12 or #14 copper wire that will work well as 1/4 wave antennas. (ask permission to scrounge first!)
I use soft copper, place one end in a vice, the other end in my drill and spin it for a few seconds while stretching the wire. This will straighten the wire and "work harden" it so it is stiffer.
Terry Graves, K7FE
Chief Editor, QRZ.COM
"Some people call CW a MODE but in
reality it is an autonomous LANGUAGE."
I have asked questions about making a Wilson Lil Will 11 meter antenna into a 2 meter antenna and was advised against it.
The ideal conversion in the 1970s was the surplus Antenna Specialists CB antenna (and its clones)
that had loading coils 3 to 4 inches in height. I still routinely find these antennas at garage sales, etc.
Here is an example of that style (this is a low-band VHF for land-mobile service)
on eBay - Item number: 320260336013
These articles can be found in Ham Radio, CQ, 73 and QST magazines of that 1975-1979 period.
I have not looked at the Wilson antenna, but many of these current CB designs are different --
so would not be easy to modify/adopt.
144-MHz antenna, 5/8-wavelength built from CB mobile whip (HN) by WB4WSU
Ham Radio magazine, June 1974, page 67
Last edited by W9GB; 09-01-2008 at 05:51 PM.
"I have asked questions about making a Wilson Lil Will 11 meter antenna into a 2 meter antenna and was advised against it."
i had the same cb mag mount antenna and at the time i was broke so i had to make it work with my 440 radio. I decided to match the antenna to the uhf rig. I used a dual sweep swr/wattmeter to get the most forward output wattage and the least movement from the swr needle for a near 1.1:1 ratio at my working frequency of 448.400mhz.
I cut the whip down to around 6 1/4 inches before i got the lowest swr reading. I was cutting small pieces at a time of course. I tested it and it hits the local repeaters and its not noisy so i can deal with that antenna until i can afford to buy a real gain antenna.
One thing i did notice is that the swr gets pretty high around 2 mhz up or down of the frequency that i matched the antenna to. I was'nt gonna be changing frequencies anyway. i'm only matched to my repeater frequency so it was good enough for me temporarily.
Anyways good luck and i hope it works out for you
if i might say i might fade like a sigh if stay you minimize my movement anyway I must pursuade you another way!@!!!!!! pushin shive pushin shove............... there's no love in fear