Aircraft Enhancement

Aircraft Enhancement occurs on 2 meters (144mHz) within the VHF band and in my experience has a close group of followers.
The distances expected with this mode of propagation are around 200 to 600Km and are quite predictable allowing communication from a few seconds to a few minutes.

Equipment Requirements for Aircraft Enhancement

Reasonably modest equipment will get you by for Aircraft Enhancement and the only real requirements are a ssb 2 meter transceiver and a horozontaly polarized antenna.
The degree of success will depend on the sensitivity of the reciever, the feed line quality and antenna gain and directivty.

The Rig

Power output from the transmitter of around 50 watts or more is recomended but a 10 watt station can do very well.
The Transciever must be an SSB 2 meter rig with as much reciever sensitivity that can be mustered up. Noise Blankers and DSP filters are also handy features. Also if no mast head preamp is used a preamp in or before the rig is very handy indeed. Good examples of Transievers for AE would be the IC-706 or FT-847.

Feed Line

Feed line should be as efficient as possible and hard line should be used. That said RG213 or equivilent will do the job for runs under 10 metres or so.

Antenna

Really I would not consider using any thing less than a 7 element yagi with sensible spacings. DL6WU designs are quite good and give good tolerances for a reasonably predictable performance. Designing the antenna at the intended operating frequency also leads to predictable performance.
At the other end of the spectrum there is no limit as to the size of the array that could be used. Just be aware that more gain generally makes for more directivity and bigger arrays.

Where do I find Aircraft Enhancement on 2M?

On the East Coast of Australia AE operators use the secondary SSB call Channel which is 144.200mHz.
USB is the mode mostly used but you will also hear CW in there as well.
There is a fairly organized schedule to it all and the action usually starts every morning from 7:00AM local time with more activity on week ends.
There is also a 2 meter DX net between VK2 and VK4 every tuesday night starting at 18:50 hours local time.

Operating Procedures
HF operators may find some of the operating behaviours on 2m SSB a bit strange to say the least, some may evewn feel that operator are bening rude or inconciderate but this can be clarified quite easily.
On 144mHz propagation paths do not often hang around for hours, particularly AE. There is some what of a gentlemens agreement that if you hear it you can call it. That said once a contact is established others must wait there turn. Also conditions can be quite selective, so you may be the only station hearing the DX at that time.
QSOs are kept very short and mostly not more than call signs, first names, grid square and signal report are given and conformations of all recieved are involved in the QSO, not forgetting 73s of course.

Maybe the strangest behaviour of all is the letter K that is often whistled at the end of a transmittion when calling CQ or signals become weak.
Some use automatic keyers to send the K in CW and some just whistle it, either way its just there to let other stations know when your transmition is over ( particularly as conditions deteriate).

As a last note, as with most call frequencies chatting on 144.100 or 144.200 is frowned upon and changing to another frequency is recomended if any thing more than a few very short overs are planned.

Good Luck. Enjoy!

VHF DX Weak Signal Propagation

Often when one over hears a group discussing VHF long distance communication via weak signal modes it conjures up thoughts of elaborate specialized equipment that has been home brewed by a retired RF Engineer or some thing to that effect but truthfully long distance communication on VHF is very accessible to the average amateur operator in most countries.
VHF and UHF have a lot to offer over HF in some key areas if one can think beyond the general belief that these bands are line of sight and nothing more.
Making contacts via weak signal propagation requires a little effort some times but often the work is in the construction and setup of equipment and this comes down to personal preferences as to how elaborate your station may be.

Minimum Requirements for 6 meter weak signal propagation.
The 50MHz or 6M band is probably the easiest band to make DX contacts on simply because it exhibits characteristics similar to both HF and VHF. The only thing with six meters is that it is a case of right place at the time but during solar maximum openings that cross the globe become quite frequent.
At times of solar minimum Sporadic E conditions can occur giving way to communication over a distance of 1200 to 2000 km.
The minimum requirements for reliable DXing on 6M would be a 6m all mode rig with 100 watts output and a 6m half wave vertical or a horizontal dipole. The use of low loss coax will be an advantage and the use of RG58 is hardly acceptable for feed line. RG213 would be a bear minimum.

Minimum Requirements 2 meter weak signal propagation.
Probably one of the most active bands in some areas of the world 144MHz has much to offer the VHF enthusiast from tropospheric ducting to sporadic E and Aircraft Enhancement.
Aircraft Enhancement offers communication up to 1000km but more frequently 300 to 500 km on a daily basis. Sporadic E and Ducting tend to be seasonal but opening out of season can occur.
The minimum requirements for weak signal work on 144MHz would be a 2m all mode rig with 10 watts or more and a 7 element yagi at least 8 metres above ground.
Feed line losses are a problem on 2m so the use of low loss coaxial cable is a definite advantage.
RG213 will get you by but hard line of some description is preferable.

VHF Weak Signal Operating Practices.