Method for improving EIRP efficiency of array-fed reflector antenna

Abstract

The application discloses a method for improving EIRP efficiency of array-fed reflector antenna, and belongs to the field of array-fed reflector antenna. The method comprises the following steps: S1. randomly initializing a binary grass population; S2. evaluating the fitness of the grass; S3. breeding and diffusing the grass population based on a probability selection mechanism; S4. evaluating the fitness of the newly generated grass; S5. competitively excluding the grass population; S6. judging whether the maximum evolution number is reached, and outputting a final solution or returning to S3. The method improves the classical invasion grass algorithm, the breeding and diffusion of the grass population are no longer based on a normal distribution mechanism but based on a probability selection mechanism, the improved algorithm can be applied to the rapid optimization of binary variables, and the obtained feed array feeding power scheme can effectively improve the EIRP efficiency of the reflector antenna.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of array-fed reflector antennas, and particularly relates to optimization of array-fed power distribution of a reflector antenna feed, and in particular to a binary invasive weed algorithm for improving EIRP efficiency of an array-fed reflector antenna. BACKGROUND

[0002] A reflector antenna is widely used in satellite communication, space radar and other fields due to its high gain and high efficiency. In order to realize beam scanning, a phased array antenna is used as a feed of the reflector antenna. In the synthesis method of a pencil beam of an array-fed reflector antenna, the conjugate field matching method is the most commonly used one. Although it can synthesize the highest efficiency, due to the focusing characteristics of the focal region field, this method can only obtain a strong tapering feed power distribution. This will cause the power amplifier to work in a low efficiency state, resulting in a decrease in EIRP and a decrease in EIRP efficiency under the condition of a certain system power consumption. In a transmitting antenna system, EIRP efficiency is more important than antenna efficiency, because EIRP represents the maximum communication or monitoring distance under a given signal-to-noise ratio requirement. Therefore, it is necessary to adjust the feed power distribution of the feed array to improve the efficiency of the power amplifier, while minimizing the sacrifice of efficiency, so as to achieve higher EIRP efficiency. SUMMARY

[0003] In view of the low EIRP efficiency of an array-fed reflector antenna designed by the pencil beam synthesis method in the prior art, the application provides a method for improving the EIRP efficiency of an array-fed reflector antenna.

[0004] The technical scheme adopted by the application is as follows:

[0005] A method for improving the EIRP efficiency of an array-fed reflector antenna, comprising the following steps:

[0006] S1. Randomly initializing a binary weed population;

[0007] Randomly generating P ini strains of weeds in the search space to form an initialized population; wherein P ini is the initial population size, and one strain of weed represents a feed array feed power distribution, and the feed power of each array element in the feed array feed power distribution only contains 0 and 1 power values, which respectively represent the off and on states of the power amplifier, and the on power amplifier works in the highest efficiency state.

[0008] S2. Weed fitness evaluation;

[0009] Calculating the fitness value of each strain of weed in the current weed population:

[0010] fitness=η a ×ηpa

[0011] wherein the fitness value fitness represents the EIRP efficiency of the array-fed reflector antenna corresponding to the power feeding scheme represented by the current weed;

[0012] η a represents the efficiency of the array-fed reflector antenna corresponding to the power feeding scheme represented by the current weed, and is calculated as follows:

[0013]

[0014] wherein G is the gain of the array-fed reflector antenna corresponding to the power feeding scheme represented by the current weed, and D is the directivity coefficient calculated according to the aperture size of the reflector;

[0015] η pa represents the average power amplifier efficiency corresponding to the power feeding scheme represented by the current weed, and is calculated as follows:

[0016]

[0017] wherein P i is the output power of the power amplifier connected to the i-th array element, η i is the efficiency of the power amplifier connected to the i-th array element, and N is the number of array elements of the feed array antenna.

[0018] S3. The weed population is propagated and diffused based on a probability selection mechanism;

[0019] Each weed in the current weed population will serve as a parent weed and generate a number of offspring weeds, and the better the fitness value of the parent weed, the more offspring weeds will be generated, and vice versa. The number of offspring weeds generated by each parent weed is determined by the following formula:

[0020]

[0021] wherein floor(·) represents the floor function, F is the fitness value of the current parent weed, F max and F min are the maximum and minimum fitness values of the parent weeds in the current population, s max and s min are the maximum and minimum number of seeds that can be generated.

[0022] The propagation and diffusion of the weed population is based on a probability selection mechanism, in which the power feeding value of each array element in the parent weed is inverted with a certain probability during the propagation and diffusion process.

[0023] Specifically, a parent weed undergoes the following process when it propagates an offspring weed:

[0024]

[0025] wherein, represents the nth characteristic of the current parent weed, represents the nth characteristic of the offspring weed, wherein the nth characteristic is the feeding power of the nth array element of the feed array, and rand is a random number, and Prob I is the probability of the feeding power value of the Ith generation weed population being taken inversely in the process of reproductive diffusion, Prob ini and Prob final are the initial and final probabilities, respectively, I and I max are the current and maximum evolution generations, respectively, and w is a nonlinear adjustment factor.

[0026] The generated offspring weeds and the parent weeds jointly constitute a new population.

[0027] S4. Evaluation of the fitness of weeds;

[0028] According to step S2, the fitness value of the newly generated offspring weeds in the current weed population is calculated.

[0029] S5. Competitive exclusion of the weed population;

[0030] It is judged whether the size of the current weed population exceeds the maximum population size P max , if it exceeds, all weeds are sorted according to their fitness values from high to low, and the top P max weeds are selected from the sorted population as the population retained this time.

[0031] S6. It is judged whether the maximum evolution generation is reached, and the final solution is output or step S3 is returned;

[0032] It is judged whether the evolution generation of the weed population reaches the maximum evolution generation, if it reaches, the feeding power scheme represented by the weed with the highest fitness value in the current population is output; otherwise, step S3 is returned, and the iterative calculation is continued.

[0033] Preferably, in step S3, the value range of Prob ini is The value range of Prob final is [1 / N, 2 / N].

[0034] The beneficial effects of the present application are:

[0035] Firstly, the present application improves the classical invasive weed algorithm, the reproductive diffusion of the weed population is no longer based on the normal distribution mechanism, but based on the probability selection mechanism, and the improved algorithm can be applied to the rapid optimization of binary variables.

[0036] Second, the feed power scheme of the feed array optimized by the binary intrusion weed algorithm proposed in this invention can maximize the EIRP efficiency of the reflector antenna. Attached Figure Description

[0037] Figure 1 This is a flowchart of the method of the present invention.

[0038] Figure 2 This is a schematic diagram of the array-fed reflector antenna in the embodiment.

[0039] Figure 3 This is a typical efficiency curve for a power amplifier.

[0040] Figure 4 The normalized feed power of the feed array designed in this invention.

[0041] Figure 5 Normalized feed power for feed array designed using the conjugate field matching method.

[0042] Figure 6 This paper compares the EIRP efficiency of the present invention and the conjugate field matching method when performing beam scanning on an array-fed reflector antenna. Detailed Implementation

[0043] To better illustrate the embodiments of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and examples. The embodiments described in this section are merely some examples of the implementation of the present invention and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0044] This embodiment provides a method for improving the EIRP efficiency of an array-fed reflector antenna, such as... Figure 1 As shown, it includes the following steps:

[0045] Step 1: Consider as follows Figure 2 The array-fed reflector antenna shown has the following parameters: D = 30λ, F = 30λ, H = 5λ, d = 3λ, θ = 3°, where λ is the wavelength. The feed array is a 14×14 patch antenna array with an element spacing of 0.5λ.

[0046] P is randomly generated within the search space. ini The initial population is formed by the formation of weeds, where P ini The initial population size is set to 5. Each weed represents a power supply scheme for the feed array, where the power supply consists only of 0 / 1 power values, representing the power amplifier being off and on, respectively, with the on power amplifier operating at its highest efficiency. Therefore, each weed is a 196×1 0 / 1 vector.

[0047] Step two: the product of the array-fed reflector antenna efficiency and the average power amplifier efficiency is taken as the fitness value of each weed in the weed population, which is the EIRP efficiency of the array-fed reflector antenna when the current weed represents the feeding power scheme, and the feeding phase still adopts the phase synthesized by the conjugate field matching method.

[0048] Here, the array-fed reflector antenna efficiency is defined as the ratio of the gain of the antenna to the directivity coefficient; the average power amplifier efficiency is defined as follows:

[0049]

[0050] where P i is the output power of the power amplifier connected to the i-th array element, η i is the efficiency of the power amplifier connected to the i-th array element, which in this embodiment is taken from the typical efficiency curve of the power amplifier as shown in FIG. 1; and N is the number of array elements of the feed array, which in this embodiment is taken as 196. Figure 3

[0051] Step three: each weed in the current weed population will be taken as a parent weed and generate a number of offspring weeds, the better the fitness value of the parent weed, the more offspring weeds it will generate, and vice versa. The number of offspring weeds generated by each parent weed is determined by the following formula:

[0052]

[0053] where floor(·) represents rounding down, F is the fitness value of the current parent weed, F max and F min are the maximum and minimum fitness values of the parent weeds in the current population, s max and s min are the preset maximum and minimum seed numbers. In this embodiment, s max = 5 and s min = 1.

[0054] The propagation and spread of the weed population are based on a probability selection mechanism, that is, each feeding power value represented by the parent weed is taken as the opposite with a certain probability in the propagation and spread process; a parent weed experiences the following process when it propagates an offspring weed:

[0055]

[0056] wherein represents the n-th feature of the current parent weed, represents the n-th feature of the offspring weed, the n-th feature here represents the feeding power of the n-th antenna array element of the feed array, and rand is a random number, Prob I ​represents the probability of the power value of the Ith generation weed population being reversed in the process of breeding and spreading, Prob ini and Prob final respectively represent initial and final probabilities, I and I max respectively represent current and maximum evolution generations, and w is a nonlinear adjustment factor. In this embodiment, Prob ini = 0.06, Prob final = 0.005, I max = 1000, and w = 3.

[0057] The generated offspring weeds and the parent weeds jointly constitute a new population.

[0058] Step four: the fitness value of the newly generated offspring weeds in the current weed population is calculated, and the calculation manner is the same as that in step two.

[0059] Step five: whether the size of the current weed population exceeds the maximum population size P max is judged, if yes, all weeds are sorted according to their fitness values from best to worst, and the top P max weeds are selected from the sorted population in turn as the population finally reserved in this evolution. In this embodiment, P max = 20.

[0060] Step six: whether the evolution generation of the weed population reaches the maximum evolution generation is judged, if yes, the power feeding scheme represented by the weed with the best fitness value in the current population is output; otherwise, the algorithm is returned to step three and continues to be executed.

[0061] Figure 4 The normalized feeding power of the array feed reflector antenna in this embodiment is given when the azimuth plane is scanned to 0°, 1°, 2° and 3°, wherein the blank indicates that the power amplifier is turned off.

[0062] Figure 5 The normalized feeding power of the array feed reflector antenna designed by the conjugate field matching method is given when the azimuth plane is scanned to 0°, 1°, 2° and 3°.

[0063] Figure 6 The EIRP efficiency of the array feed reflector antenna in the beam scanning process by the conjugate field matching method and the present application is given. It can be seen that the feeding power scheme obtained by the present application can improve the EIRP efficiency of the array feed reflector antenna from 6% of the conjugate field matching method to 28%, corresponding to 4.7 times of EIRP improvement. This means that under the same signal-to-noise ratio requirement, the communication or monitoring distance of the array feed reflector antenna can be 2.2 times of the original.

Claims

1. A method for improving the EIRP efficiency of a phased array reflector antenna, characterized by, The method comprises the following steps: S1. Randomly initializing a binary weed population; P is randomly generated within the search space ini Weed, forming an initial population; wherein, P ini is the initial population size, and a weed represents a set of feed array power feeding scheme, in which the power feeding of each array element only contains 0 and 1 power values, representing the power amplifier off and on, respectively, and the on power amplifier works in the highest efficiency state; S2. Evaluating the fitness of weeds; The fitness value of each weed in the current weed population is calculated: fitness = η a x η pa Wherein, the fitness value fitness represents the EIRP efficiency of the array-fed reflector antenna corresponding to the power feeding scheme represented by the current weed, η a the efficiency of the array-fed reflector antenna corresponding to the power feeding scheme represented by the current weed, η pa the average power amplifier efficiency corresponding to the power feeding scheme represented by the current weed; S3. Reproduction and diffusion of the weed population based on a probability selection mechanism; Each weed in the current weed population will serve as a parent weed and generate a number of child weeds, and the better the fitness value of the parent weed, the more child weeds will be generated, and vice versa; The reproduction and diffusion of the weed population is based on a probability selection mechanism, and the probability selection mechanism is that the feeding power value of each element in the parent weed is inverted with a certain probability during the reproduction and diffusion process; Specifically, a parent weed undergoes the following process when it reproduces a child weed: wherein, represents the nth characteristic of the current parent weed, represents the nth characteristic of the offspring weed, where the nth characteristic is the feeding power of the nth array element of the feeding array, and rand is a random number, Prob I is the probability of the feeding power value being inverted during the process of reproduction and expansion of the Ith generation weed population, Prob ini and Prob final are the initial and final probabilities, respectively, I and I max are the current and maximum evolution generations, respectively, and w is a nonlinear adjustment factor; The generated child weeds and the parent weeds together constitute a new population; S4. Evaluating the fitness of weeds; The fitness value of the newly generated child weeds in the current weed population is calculated according to step S2; S5. Competitive exclusion of the weed population; determining whether the current weed population size exceeds the maximum population size P max If so, all weeds are sorted according to their fitness values from high to low, and the top P max weeds are selected from the sorted population as the population to be preserved in this evolution. S6. Determine whether the maximum evolution number is reached, output the final solution or return to step S3; Determine whether the evolution number of the weed population reaches the maximum evolution number, if yes, output the feeding power scheme represented by the weed with the highest fitness value in the current population; otherwise, return to step S3 and continue iterative calculation.

2. The method of claim 1, wherein the EIRP efficiency of the array-fed reflector antenna is improved by, In step S2, the current weed represents the corresponding array-fed reflector antenna efficiency η of the power supply scheme a The calculation method is as follows: Wherein, G is the gain of the array-fed reflector antenna corresponding to the feeding power scheme represented by the current weed, and D is the directivity coefficient calculated according to the aperture size of the reflector.

3. The method of claim 1, wherein the method further comprises: In step S2, the average power amplifier efficiency η corresponding to the power feeding scheme represented by the current weed pa is calculated in the following manner: where P i is the output power of the power amplifier connected to the i-th array element, η i is the efficiency of the power amplifier connected to the i-th array element, and N is the number of array elements of the feed array antenna.

4. The method of claim 1, wherein the method further comprises: In step S3, the number of child weeds generated by each parent weed is determined by the following formula: where floor(·) denotes the floor function, F is the fitness value of the current parent weed, F max and F min are the maximum and minimum fitness values of the parent weeds in the current population, s max and s min are the maximum and minimum number of seeds that can be produced, respectively.

5. The method of claim 1, wherein the method further comprises: In step S3, Prob ini has a value in the range Prob final has a value in the range [1 / N, 2 / N].

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