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# Airport entrance traffic detection

## Airport entrance traffic detection

(OP)
What are the chances that a few K-band microwave traffic detectors at an airport's main entrance would interfere with airport operations? The in-ground inductance loops have failed and I'm looking for a cheaper alternative than cutting in new ones.

Thanks!

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

### RE: Airport entrance traffic detection

how much range/power will these detectors have ? (not much i suspect)

why not use a visual light detector ?

### RE: Airport entrance traffic detection

(OP)
@rb1957 I haven't yet found a power spec. Range is listed as 250 ft, so they must be less powerful than police speed enforcement radars.

Our state DOT's bid price results list microwave detectors at $1200 each, installed. Video detectors are listed as$58,000 each. I suspect that would be lower in areas that use more if it.

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

### RE: Airport entrance traffic detection

I am not a traffic engineer, but I do have some general experience on aircraft with radar.

K band radar is very much line of sight, so if you don't have a wide angle aperture, and you have the very low power needed for only 250 feet range, you should be able to keep interference from being an issue.

K band radar on aircraft can be used for weather detection out to decades of miles with 100 watts of power, so for your 250 range the power would be very greatly reduced from that value, I would guess.

Someone who has land based experience can help you much better than I, but I would expect that as long as any structures reasonably close to the parth of the beam you would be transmitting would have walls of either metal or thick concrete would tend to absorb that small amount of radiation before it penetrates and interferes internally.

If you can site the transmitter path so that it is very unlikely to bounce upwards or towards parked/taxiing aircraft that would be a good idea.

Shielding the reception component from radar energy from any direction except the desired transmitter would be a very good idea.  Any aircraft with a K band radar (aircraft typically carry either X band or Ku band but Ku band is right next to K band) could set off your receiver with the right combination of bounces.  Aircraft weather radars normally do not ever transmit while on the ground (although occasionally for maintenance testing they might) so I would think that might be low risk.

But as I said this is very general, you want to talk to a radar engineer who does ground based radar siting work.

### RE: Airport entrance traffic detection

(OP)
Thanks to everyone for the input. I found a later set of plans that showed the inductance loops were replaced by a microwave radar about 11 years ago, so all we have to do is replace the existing unit.

The radar is pole mounted, ~20 feet up, pointed down and away from the airport, so I expect interference would be minimal. It isn't where I expected it to be.

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

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