Broadband radar and modulator, in particular for microwave switching over a very short period
The present invention relates to an ultrawideband radar. It also relates to a modulator, in particular for switching microwaves over a very short duration. The radar includes a modulator modulating a carrier microwave, this modulator including a microwave mixer means for generating a modulation signal. The microwave enters on one input of the mixer and the modulation signal on the other input of the mixer, the output signal from the mixer being provided to the transmission means of the radar. Advantageously, the modulation signal may be pulsed and of very short duration. A local oscillator, operating as a free oscillator, provides the microwave to be modulated. The invention applies in particular in respect of aiding the parking of motor vehicles. More generally, it applies in respect of all applications which require low-cost high distance resolution radar detection.
1. A radar comprising:
a local oscillator providing a microwave signal;
a receive antenna linked to reception means, the signal at the output of reception means being intended for processing circuits;
a modulator modulating the microwave signal provided by the local oscillator, the modulator comprising means for generating a modulation signal, wherein, the modulator has a microwave mixer, the microwave signal entering on one input of the microwave mixer and the modulation signal entering on another input of the microwave mixer, the output signal from the microwave mixer being provided to transmission means of the radar, wherein the modulation signal is pulsed,
wherein the local oscillator operates as a free oscillator.
2. The radar as claimed in claim 1 , wherein the local oscillator operates as a free oscillator.
3. The radar as claimed in claim 1 , wherein a transmit antenna is linked to the output of the mixer.
4. The radar as claimed in claim 3 , wherein the antenna is linked to the mixer via amplifying means.
5. The radar as claimed in claim 1 , wherein the reception means comprise at least one microwave mixer, the receive antenna being linked to the input of at least one microwave mixer whose other input receives the microwave, the demodulated signal obtained at the output of the mixer being intended for the processing circuits.
6. The radar as claimed in claim 5 , wherein the reception means comprise a dual mixer, a circuit placed on the input path of one of the two mixers phase shifting the carrier wave by π/2.
7. The radar as claimed in claim 1 , wherein the modulator provides several pulses per recurrence period.
8. The radar as claimed in claim 7 , wherein the modulator provide a pseudo-random code.
9. The radar as claimed in claim 7 , wherein the means provide a code taking the values −1 or 1.
10. The radar as claimed in claim 7 , wherein the code is a polynomial whose periodicity is greater than the outwardlretum propagation time to a target of maximum range.
11. The radar as claimed in claim 1 , wherein the means for generating the pulses are a digital circuit moreover comprising the reception signals processing circuits.
12. The radar as claimed in claim 1 , wherein it processes the distance bins in a periodic manner.
13. The radar as claimed in claim 1 , wherein the antennas each consist of an array of patches.